Mechanisms of Disease 2 2020/2021 UL

Deze bundel bevat uitwerkingen van alle hoorcolleges, patientdemonstraties en eventuele (proef)tentamens van het blok Mechanisms of Disease 2 van de studie Geneeskunde aan de universiteit Leiden.

Bundle items:

Mechanisms of Disease 2 HC2: Cancer genetics

A normal epithelial cell has to go through several stages to be transformed into a metastasizing tumor. There is a progressive development from normal to neoplastic tissue, with many non-malignant intermediate stages. Cancer development is driven by the accumulation of mutations:An initiating mutation occurs in a normal cell → gives the cell a growth advantage over his neighboring cellsDuring life, a second mutation occurs → accelerates growth furtherA third and fourth mutation occurs → formation of a tumor A mutation is a permanent alteration in a parental DNA-sequence → a cell or organism. If it is in a parental organism, it is a hereditary mutation → is transferred to a child. If it occurs in a cell, the mutation is transmitted to the daughter cells. There are two classes of mutations:Chromosome mutations: may affect the expression of many genesChromosome losses/gainsTranslocationsMulti-locus deletionsGene mutations: may affect the expression of a few genesDeletions/insertionsBase pair substitutionsFrameshift mutations In case of multi-locus deletions, a fairly big part of a chromosome is deleted. This leads to a loss of function of the deleted alleles. Deletion on an autosomal chromosome leads to hemizygosity for multiple genes → only copy of the allele remains. Hemizygosity means that only 1 copy of the gene is left in 1 cell. If there is a gene that consists of 5 exons, and there is a deletion of exon 2 and another deletion of exon 2 and 3, the mutation is intragenic. This doesn’t necessarily lead to loss of function, but most of the time, it does.This has mutagenic consequences:If exon 2 is deleted, the reading frame doesn’t...

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Mechanisms of Disease 2 HC3: Cancer biology

There are 10 hallmarks of cancer which distinguish epithelial cells from carcinomas:Deregulating cellular energeticsSustaining proliferative signalingEvading growth suppressorsAvoiding immune destructionEnabling replicative immortalityActivating invasion and metastasisInducing angiogenesisResisting cell deathGenome instability and mutationTumor promoting inflammationTumor promoting inflammation and genome instability and mutation are enabling characteristics → enhance the cancer development progress. The other hallmarks are fundamental changes in cell physiology. When proliferative signaling is sustained, growth is stimulated constantly:A growth factor binds to a growth factor receptorThe growth factor receptor activates molecules, for instance RasActive Ras phosphorylates kinasesKinases cause cell cycle progressionCell growthThe phenotype is dominant → only 1 allele needs to be mutated. Some tumor cells:Secrete their own growth factorsBecome independent of growth factors from the outsideModify their cell surface receptorsThe receptors are constantly activated → don’t need growth factors anymoreMutate their intracellular signal moleculesMutate transcription factorsMutate components of the cell cycle network Normal body cells are in equilibrium with growth suppressors and growth promotors. There are several checkpoints for controlling this:R-pointDNA-integrity checkpointWnt signaling The R-point is the restriction point. Here, the Rb protein plays an important part → phosphorylation of Rb is necessary to release the restriction point. The Rb pathway is mutated in virtually all types of tumors. The Rb pathway can be inhibited by itself or by other means such as:Loss-of-function mutations of growth inhibitorsTGF-bINK4aGain-of-function mutations of growth...

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Mechanisms of disease 2 HC4: Cancer etiology

There are multiple risk factors for cancer. The most important ones are:AgeThe number of times a cell has dividedGenetics/hereditary: syndromes that lead to cancer, mainly in DNA repairLynch syndrome: predisposes to colon and endometrial cancerLi Fraumeni: TP53 mutationBRCA1 and BRCA2 → breast cancerCowden: PTEN mutation → breast, thyroid, uterine, renal and colon cancerEnvironmental factorsTobaccoAlcoholChronic inflammationDietHormonesImmunosuppressionInfectionObesityRadiationSunlightRisk factors can be split into controllable and non-controllable risk factors. Most are non-controllable, such as age and gender. Age is the greatest risk factor for cancer development. The peak of incidence of cancer is around 70 years. This isn’t equal for all cancer types → during puberty, the incidence of bone cancer rises due to fast growth.The more someone ages, the more times cells are divided and the more likely it is that mistakes are accumulated in DNA-strands. Because there are 3 billion base pairs, mistakes occur easily. Odds are generally against cancer:There is a minority of mutations in oncogenes and TSGsMutations are much more likely to occur outside these genesThere are DNA repair mechanismsMake sure that if mistakes happen during replication, they are repairedSeveral features need to be acquired by cells to go from a healthy cell to a malignant cellThe 10 hallmarks of cancer Nevertheless, if someone lives long enough, many cell divisions occur and the chance of developing mutations becomes more likely. Because stem cells have to supply a constant amount of new cells throughout life, they divide a lot. This can cause mutations to accumulate at different sites. Hereditary means segregating in the family → transmission of cancer material. There is a familial high chance of...

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Mechanisms of disease 2 HC5: Hereditary aspects of cancer

The chance of getting cancer increases with age:8% by the age of 6525% by the age of 8032% by the age of 100If someone has a sibling with breast cancer and is 40-50 years old, the chance of developing breast cancer is 2x as high as usual. In case of colon cancer, the cancer is 3x as high. Among monozygotic twins, the risk is higher → genetic factors play an important role in the risk of developing cancer. There are 14.000 new diagnoses of breast cancer per year in the Netherlands, of which 3.500 die every year. 13% have a first degree relative.Genetic factors play a role in whether or not someone develops breast cancer:High/medium penetrant genesLow penetrant genes/loci/SNPsThere are 200 SNPs (single nucleotide polymorphisms) that increase the risk of breast cancer → per SNP, the increase is 0,1%, but multiple SNPs can be present at the same time. Genetic counseling is useful to:Recognize patients and their families with inheritable cancerImprove morbidity and mortality by early recognition and treatmentPsychosocial guidance and advice Many cancer-causing genes have been discovered. Examples are:RB geneAPC geneMismatch repair genesBRCA1 and BRCA2CDKN2AMUTYHBAP1 1 of the following situations has to be present to test for genetic breast cancer (BRC):BRC occurs at <40 yearsBilateral BRC or multiple tumors in 1 breast with 1 tumor <50 yearsFirst grade male with BRCBRC <50 years and prostate cancer <60 years in the same branch of familyBRC <50 years and 1 or more first degree with BRC <50 yearsBRC and 2 or more first and/or second degrees with BRC, of which at least 1 <50 yearsOvarian cancer irrespective of ageHave a 10% risk of a germline BRCA1 or BRCA2 mutation ...

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Mechanisms of Disease 2 HC6: Cancer and genome integrity

Many cell divisions are required in embryonic development and during human life. Daughter cells inherit identical DNA. Cell division requires accurate DNA duplication and takes approximately 5 hours. 6 x 109base pairs are copied almost flawlessly → there is less than 1 error per division. If not repaired, DNA lesions can lead to mutations. Mutations can arise during regular DNA replication → DNA replication errors. Base mis-incorporation can occur, for example, a T can be inserted opposite of a G. Originally, there are 60.000 errors per cell division. However, there are several processes to correct such mistakes:Proofreading by DNA polymerase + exonucleaseExonuclease activity makes it possible for DNA polymerase to misincorporate a base, go back to the former situation and try it againGermline mutations in POLE and POLD1 (the main polymerases that replicate DNA) predispose to colorectal adenomas and carcinomasReduces misincorporation by DNA polymerase from 10-5to 10-7→ 600 errors per cell divisionMismatch repairRemoves the newly synthesized strand, so that polymerase can try it againOccurs if exonuclease has not been able to remove the incorrect baseReduces the error rate during DNA replication from 10-7 to 10-9 or 10-10 → there is less than 1 error per cell division on undamaged DNA Lynch syndrome is a hereditary colon cancer. In case of Lynch syndrome, there is a mismatch repair deficiency. Several mutations predispose to developing Lynch syndrome, such as mutations in:MLH1MSH2MSH6PMS2 Humans are continuously exposed to sources which damage DNA. DNA damaging agents can form threats to genome stability:LifestyleEnvironmental or industrialMedical applicationFood source In case of...

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Mechanisms of Disease 2 HC7: Clinical relevance of genetic repair mechanisms

BRCA and Lynch syndrome occur very frequently in the population. Both syndromes are caused by DNA repair genes.Even though germline mutations are equally distributed through the genome, hereditary cancer cases associate with syndromes caused by mutations in DNA repair genes. On the other hand, cancers related to inherited APC-mutations are also relatively frequent. There is an association between DNA repair defects and clinical prognosis. Lung cancers have much more mutations than breast cancers. However, if there are more mutations, a tumor doesn’t necessarily have a worse prognosis. There are several reasons for this:There can be too much DNA damage in cancer cells → essential cancer genes are hit → the cell dies due to excessive damagePoint-mutations are not the only alterations that occur in a cancer cell → tumors with very few mutations may have very abundant chromosomal mutations Colorectal cancer can develop in several different ways:A minority develops under very specific defects in the DNA repair machineA small proportion (less than 5%) develops under deficiencies in the proofreading domain of polymerase chains → accumulate to a lot of mutations in their coding gene15-20% develops under the context of mismatch repair deficiencyA large majority has a low number of mutations in their genome but a large chromosomal instabilityEven though MMR-deficient (mismatch repair deficient) or POLE-mutated (polymerase mutated) tumors have more mutations than MMR-proficient tumors, they have a better prognosis up to stage 3. In stage 4, the prognosis is equally bad for all tumors. This means that more mutations actually result in a better prognosis. This can be explained by:There being too much damage → affects the tumor cellsChromosomal instability leading to a...

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Mechanisms of Disease 2 HC8: General principles: diagnostic pathology

A spiculated mass is a mass with spikes going into the surrounding tissue. Benign lesions generally don’t grow in this type of fashion → a biopsy needs to be taken. FNAC stands for fine needle aspiration cytology:A little bit of tumor is taken from the lesion with a needleThe tumor is spread out on a small glassColor is added → rapid stain-RALThis is a stain which takes 40 secondsThis isn’t a histology biopsy, because the cells are loose. Biopsies can be taken to test for breast cancer. Various cells become visible:TumorsCells without a nucleus → erythrocytesIrregular cells vary in sizeIn a normal situation, the following is visible:Low cellularityCohesive cell-groupsCells are small and have the same size and shapeSmall cellsMaximal 1,5x the size of an erythrocyteSigns of cancer cells are:Large, variably shaped nucleiHyperchromasiaThe nucleus is darkerPolychromasiaMany dividing cells → disorganized arrangementCells come loose from epitheliaVariation in size and shapePolymorphismPleomorphismLoss of normal features Several important terms are:Benign: not harmfulMalignant: harmfulAtypia: a clonal proliferationDuctal carcinoma in situ (DCIS): not yet cancerThe cells look malignant, but this doesn’t actually prove that the lesion is malignantA tumor is malignant when:Invasion occurs → malignant tumors recognize no anatomic boundariesCells have the ability to metastasize → can invade blood and lymphatic vessels A carcinoma can be invasive or in situ. Which of the 2 is the case cannot be seen on a biopsy:Normal breast tissue is made of fat and ductDucts transport milk to the nippleA duct contains an epithelial luminal layer which can transport and form the milkWhen hyperplasia occurs in those...

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Mechanisms of Disease 2 HC9: Nomenclature and grading of cancer

There are many kinds of mesenchymal tumors:Fat: lipo-Bone: osteo-Fibrous: fibr-Cartilage: chondro-Blood vessels: hemangio-Muscle: leiomyo-/rhabdomyo-These tumors can be benign of malignant:Benign: -omaCells are nicely organizedMalignant: -sarcomaSarcoma means flesh → malignant tumors are fleshyCells aren’t organized Epithelium is the coverage and lining of the body. Tumors can be:Glandular or ductalSquamous and stratifiedEpithelial tumors can be benign of malignant:BenignAdenomaCystadenoma: a cyst originating from a ductPapillomaMalignantCarcinomaAdenocarcinoma: carcinoma in the colonPapillary carcinoma Melanocytes can be benign or malignant:BenignNevus: a moleMalignantMelanomaIn this case, “-oma” stands for a malignant disease Tumors in testicular epithelium are always malignant → seminomas.Totipotent cells can form all kinds of tissues. They are also located in the testis and ovaries. Tumors are called teratomas:BenignMature teratomaMalignantImmature teratoma/terato-carcinomaIn women, teratomas are often benign. They can contain all types of tissues, even complete teeth. Salivary glands have many different features. Tumors in salivary glands can vary greatly. They can be benign or malignant:BenignPleiomorphic adenomaHas a high recurrenceMany othersMalignantMucoepidermoid carcinoma(Basal) adenocarcinomaAcinic cell carcinoma Grading defines the impact of grade and stage in different malignancies and can explain the differences between these features. A grade can be used as a biomarker, which is:Prognostic: for example of the chances of metastasisPredictive: for example of the chances of response to certain types of therapy...

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Mechanisms of Disease 2 HC10: General principles: metastasis

Metastasis is Greek word, which in medical use describes the shift of disease from one part of the body to another. It is mainly used in context of cancer. In the 19th century, Jean Claude Recamier recognized that cancer can spread from a primary tumor. Stephan Paget came up with the seed-and-soil theory. He stated that the growth of a tumor is not a matter of chance, but that there must be an affinity between the tumor cells and the site where they are metastasizing. Sister Mary Joseph noticed that a tumor in the umbilicus usually is a metastasis of a tumor elsewhere → a sister Mary Joseph node is a secondary lesion in 1-3% of abdominal cancers. Its metastatic route is unclear. In 1929, James Ewing states that metastatic dissemination occurs by purely mechanical factors. The mechanistic theory states that mechanical forces and circulatory patterns between the primary tumor and the secondary site account for organ specificity. This forms a contradiction to the seed-and-soil theory. In the end, both theories proved to be correct → depends on the cancer type. In 1965, Bernard Fisher described breast cancer as a systemic disease. He stated that early-stage breast cancer can be more effectively treated by lumpectomy, in combination with radiation therapy, chemotherapy and/or hormonal therapy than by radical mastectomy. Mastectomy is an extremely invasive procedure where the breasts, muscles and lymph nodes are removed. If metastasis has already occurred, such treatment isn’t useful. In 1975, Isiah Fidler stated that metastasis is the result from the survival of only a few tumor cells. The process of metastasis and invasion is comprised of several stages:A primary tumor is proliferating...

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Mechanisms of Disease 2 HC11: General principles: molecular diagnostics

Molecular diagnostics is a subspecialty of pathology that utilizes molecular biology techniques to:Detect normal and disease statesMake a prognosisIdentify druggable targetsMolecular biology techniques utilize DNA, RNA and enzymes that interact with nucleic acids to understand biology at a molecular level:KRAS mutationsEGFR deletionEML4-ALK or ROS translocations in NSCLCEt cetera (Proto)oncogenes have several therapeutic targets based on the hallmarks of cancer:Growth factorGrowth factor receptorIntracellular signal transduction pathwayCell cycle regulatorsTranscription factorsAnti-apoptotic factorsAbnormal activation of these targets leads to cancer. This activation can be caused by:Dominant mutations at cellular levelSingle mutations → 1 allele is sufficient In a tumor cell, chromosomes become heavily dysregulated. This can even lead to entire chromosomes changing. When the chromosome number changes, it is called aneuploidy. Activating mutations can be divided into 3 categories:TranslocationPoint mutationsMissense mutationsAn amino-acid is changed into another amino-acidNonsense mutationsA stop codon is introduced instead of an amino acid → truncated proteinSilent mutationsEven though a base pair is changed, it still codes for the same amino acidIndel/frameshift mutationsA base is deleted and the next nucleotide is taken for translationAmplificationA normal gene becomes amplified and has multiple copies Molecular diagnostics are useful to diagnose several things:Tumor phenotypeMalignancyOrigin of the tumorHeredity Therapy can consist of:Personalized medicineTreatment of cancerDrugs targeting specific mutations/pathways The vast majority of...

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Mechanisms of Disease 2 HC12: How did cancer become the emperor of all maladies?

Cancer is the emperor of all maladies, the king of all terrors. The attention to and visibility of cancer is growing:In Greek and Roman times, cancer was visible but not so prominentMore and more research of tissues is doneAround 1900, cancer became a new interest → a public health concernThe interest in occupational and environmental causes and complexity started growingCancer has become a more and more visible disease over the last two centuries. It has developed into the disease of modern times. The disease became a major object of medical, social, economic and political concern. In the 17th century, breast cancer was seen as a female disease because only in women it was visible on the outside. Breast amputation was preformed, which had to be done very fast. Of course, men also had breast cancer, but they attributed the signs to something else than a tumor in the body. Breast cancer was connected with lust in sexuality because no breast cancer was found in nuns. In the 19th century, a first turning point in cancer history occurred. It was stated that diseases weren’t located throughout the entire body, but could emerge from certain tissues and other parts. There was a localist approach focused on cells, tissues and organs. Doctors opened up a body and found tumors inside. Rudolf Virchow made an important statement: “all cells arise from other cells and malignant cells grow too fast”. In 1900, the words cancer genetics and oncologist did not exist. Chemotherapy wasn’t present, but a cancer hospital was. Radiation therapy could already be preformed. In 1913, the Netherlands Cancer Institute (NKI) was established.In the early 20th century, cancer increasingly became a public health problem. This formed a second turning point. It statistically came more to the...

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Mechanisms of Disease 2 HC13: Heterogeneity in cancer

In cancer, there are 3 types of heterogeneity:Inter-patient: between patientsInter-tumor: between tumorsIntra-tumor: within the tumorExamples are:Well/moderately differentiated versus poorly differentiatedTumors with a strong T-cell infiltration versus with a poor T-cell infiltrationCancer cells are different when they are at the core than when they are at the invasive marginBecause the environment is differentFor example the amount of immune cells or the access to oxygenThe more clones there are in a tumor, the more likely the chance that 1 is able to metastasizeHeterogeneity forms a major issue for the treatment of cancer. There are 2 origins of intra-tumor heterogeneity:Every time a tumor cell divides, it is an opportunity for a new clone to ariseDNA repair deficient tumors are likely to be more clonal heterogenousThe fact that a new clone evolves, doesn’t mean it will survive:It has to compete with other clonesCompetition for nutrients/oxygenProliferationIt has to evade the immune system Inter-tumor heterogeneity is a morphological heterogeneity between tumors → one tumor is well/moderately differentiated while the other is poorly differentiated.Heterogeneity becomes clear when the protein expression is observed. For instance, 1 tumor can have high levels of PD-L1 expression while the other doesn’t. Tumor cells which are negative for PD-L1 respond negative to the treatment.Not only the tumor cells present in tumors can differ, but also other cells, for instance immune cells. Heterogenic tumors arise as follows:Epigenetic changes occur during cell divisionA clone that is able to evade the immune system survives and keeps dividingThe clone keeps getting better at...

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Mechanisms of Disease 2 HC14: Cancer immunity and immunotherapy

The incidence peak of cancer is around the 6th decade of life. Therefore, it isn’t important in the evolution or in shaping the immune system → mainly occurs after reproductive age.In the beginning of the 20th century, a number of scientists proposed a theory of immune surveillance, which later was further confirmed:If a mouse is injected with a carcinogen, a tumor starts developingIf the tumor is injected into another mouse, the tumor continues developingIf the tumor is first subjected to radiation and vaccinated into a mouse, the tumor stops growingThis shows that the immune system plays an important role in tumor growth. The presence of certain immune cells correlates with both improved and worse tumor behavior and prognosis. T-cells are associated with both a good and bad prognosis, depending on the type:Presence of CD8 T-cells correlates with a good prognosisPresence of tertiary lymphoid structures are a good signPresence of regulatory T-cells are associated with a worse prognosis → immune suppressive role Macrophages are often associated with immunosuppressive activity. They can produce cytokines like IL-10 or TGF-β, which counteract immune activity. There are 2 types of macrophages:M1: pro-inflammatory → better prognosisM2: immunosuppressive → worse prognosisThe majority of macrophages in tumors are M2 → make a bad prognosis. When a cell is targeted by carcinogens such as UV-radiation or cytotoxic drugs, the following happens:Damage response pathways are activated, such as:ATMP53When these proteins are activated, they induce the expression of a number of stress molecules which go to the surface of cellsThe proteins are recognized by NK-cells or CD8 T-cellsThe target...

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Mechanisms of Disease 2 HC15: Framework oncology and staging

A tumor grade reflects intrinsic biological behavior of tumors. In general, a low grade is less aggressive. It is necessary to grade a tumor for treatment and prognosis:Lower grade → better prognosisHigher grade → worse prognosisTumors are graded based on the microscopic appearance of cancer cells. Dependent on the tumor, there are 2-4 degrees of severity. An example is:GX: grade cannot be assessedUndetermined gradeG1: Well-differentiatedLow gradeG2: moderately differentiatedIntermediate gradeG3: poorly differentiatedHigh gradeG4: undifferentiatedHigh grade The amount of grades differs per tumor type. In case of breast cancer, there are only 3 grades. These grades can be linked to the expected 5 year survival rates:Total: 91-95%Grade I: 75%Grade II: 53%Grade III: 31% Tumor staging is used to determine the extent of disease spread in patients:Solid tumorsLocal spreadThrough lymphatics (lymphogenic)Distant (hematogenic)Haemotological malignanciesTells something about the disease extent and influence on normal bone marrow functionCancer staging is useful for:Planning treatmentEstimating prognosisIdentifying clinical trials/studiesMaking a comparison between institutesCommunicationStaging is a universal languageThere is no unique staging system. However, most staging systems do consist of several common elements:Location of the primary tumorTumor size and number of tumorsLymph node involvementSpread of cancer into the lymph nodesCell type and tumor gradeHow closely the cancer cells resemble normal tissuePresence or absence of distant metastasisIn general, the higher the stage, the worse the prognosis. The TNM staging principles is the most used staging system for solid tumors:T-status: extent of the tumorT1-T4...

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Mechanisms of Disease 2 HC16+17: Pharmacology I&II

To determine what therapy is effective, it is necessary to make a therapeutic plan. This can be done according to the WHO 6STEPS method:Step 1: evaluate the problems of the patientStep 2: identify the goals of therapyStep 3: list the treatment options (indication related)Step 4: provide the rationale for the best treatment for this patientStep 5: write a definitive therapy plan (prescription)Step 6: determine the monitoring parameters/follow-upTo make a therapeutic plan for a specific patient, it is necessary to understand:The pathology of the diseaseThe target sites of therapyThe mechanisms of actions of a drug Cancer is a heterogenous disease → it has different causes and requires different treatments. There are 3 main forms of cancer treatment:SurgeryRadiotherapyPharmacological therapyTo make a patient-specific therapeutic plan, the following needs to be determined:Type of tumorGrowth velocityMetastasesSometimes, curation isn’t possible anymore and treatment is palliative. Palliative treatment consists of:Pain managementSupportive care There are 4 groups of pharmacological therapy which can be used as cancer treatment:CytostaticsHormonesImmunomodulatorsTarget therapy The core medication list consists of the most used drugs for cancer. It is necessary to know the:IndicationMechanism of actionRelevant side effectsOne or 2 drug examplesThe core medication list is built up as follows:Cytostatic drugsAlkylating and related agentsCyclophosphamideCisplatinAntimetabolitesMethotrexateFluorouracil (5-FU)CytarabineAntimitoticPaclitaxelTopoisomerase-inhibitorsDoxorubicinHormonal drugsAntihormonesTamoxifenAromatase-inhibitorsAnastrozolProgestagensMegestrolacetateLHRH-analogues...

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Mechanisms of Disease 2 HC18: Biomarkers for early detection of cancer

Cancer can be diagnosed based on:Physical examinationBlood testsCT-scansBiopsies to obtain tumor tissueA biomarker refers to a measurable indicator of some biological state or condition. Humans shed particles into the bloodstream or environment as evidence of their presence in a particular location:Small parts of cellsMicroparticlesExosomesProteinsUnique chemicalsDNA and RNABiomarkers are measured and evaluated to examine:Normal biological processesPathogenic processesPharmacologic responses to a treatmentTherapeutic interventionAn ideal tumor marker for diagnosis:Should have great sensitivity, specificity and accuracy in reflecting the total disease burdenShould be prognostic of the outcomeShould be predictive of tumor recurrenceShould be predictive of effectiveness of anti-cancer treatmentsSamples for biomarker detection are:Blood, urine or other body fluidsTissuesTumor cells and products circulate in blood and are easily detectable. However, tissue forms the issue. There is a limited access to tissue:Archival tissue is not obtained at the time of clinical decisionAccessible metastatic tissue may not be representative Because tissue access is limited, there is an increased interest in circulating tumor cells (CTCs). CTCs shed by primary and metastatic tumors can be used as “liquid biopsies”, providing real-time information about the patient’s current disease state. Molecular profiling in CTCs can be used for patient selection to stratify for targeted therapy or serve as well-defined treatment targets. Potential clinical applications of CTCs are:Blood testing using CTCs may aid in cancer diagnosisMay serve as prognostic and predictive biomarkersChanges in CTC counts could indicate sensitivity or resistance to anti-cancer therapy monitoringCTC enumeration...

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Mechanisms of Disease 2 HC19: Surgical oncology

In 2012, there where 14 million new cancer cases, 8 million cancer deaths and 33 million people living with cancer. These numbers will only increase. Even though surgeons aren’t the only doctors involved in cancer therapy, 80% of all solid cancers need surgery.Surgical oncology has several challenges which need to be taken into account:Survival/cureRisk of recurrenceMorbidity/mortality of treatmentQuality of life/functionalityCostsThere is an evolution in surgery from more invasive to less invasive. There are several types of surgical oncology:CurativeMinimal invasiveAcutePalliativeProphylactic Curative surgery is an intervention with the aim of curing the disease. Several things happen:En-bloc resection: removal of the primary tumor and all the adjacent tissue which can contain micro-metastasesE.g. breast amputation + removal of the nearby lymph nodesNo-touch technique: as little as possible has to be done with the tumor itself during its ejection → prevents tumor cells from detaching and metastasizingThis can be done with vasculature isolation → the vessels are isolated so the tumor cells can’t travel anywhereClips: mark the site where the original tumor was → the radiation therapist knows where to provide additional therapyRinsing the surgical field There are 3 situations in cancer where acute surgery is necessary:PerforationObstructionBleedingWhat kills first, has to be treated first. An example of this is the removal of a tumor which obstructs the colon → the tumor is removed to restore the normal function. Chances of cure in case of acute surgery are much lower than in normal, elective surgery. Palliative surgery is an intervention with the aim of easing the complaints of the patient. The chance of curation is 0%.Palliative surgery may...

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Mechanisms of Disease 2 HC20: Radiation oncology

Radiation oncology is a separate discipline in oncology where ionizing radiation is used to treat cancer. It is not the same as radiology or nuclear medicine:Radiation oncology uses as much radiation as possible, radiology uses as little radiation as possibleNuclear medicine is done with the use of soluble radionuclides, radiation oncology uses linear accelerators and fixed sources50% of cancer patients are irradiated. Radiotherapy can be a form of curative or palliative treatment. Together with other treatments, it increases the numbers of long survivors. There are several types of ionizing radiation:α-radiationLow penetranceCan be stopped by a piece of paper → not often usedSometimes used with cell cultures to measureβ-radiationOften usedγ-radiationMost usedH+-radiation (protons)Sometimes usedElectronsSometimes usedLow penetranceIdeal for superficial tumors (skin cancers) → doesn’t affect deeper laying tissues External beam radiotherapy uses the photons of γ-rays. A linear accelerator can be turned on or off. This is a form of local treatment → there only is radioactivity when the linear accelerator is on. Afterwards, patients won’t be radioactive anymore. Radiation oncology has the following mechanism of action:Radiation causes DNA-strand breaksThis can happen due to direct photon-DNA interaction, but mostly due to indirect interaction: photons activate oxygen radicals → cause DNA damageDouble strand breaks, single strand breaks and other kinds of DNA damage are being causedNormal cells recognize and repair most of the damageCancer cells have less regenerative capacity and die at cell divisionThe aim is to kill the tumor. The side effects of the therapy are determined by the slow down of cell division in surrounding healthy tissues....

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Mechanisms of Disease 2 HC21: Medical oncology

An oncologist is a doctor who treats cancer and provides medical care for a person diagnosed with cancer. The field of oncology has 3 major areas:SurgeryRadiationMedicalA medical oncologist treats cancer using hormonal therapy, chemotherapy or other medications such as targeted therapy or immunotherapy. Drug treatments can attack all the cancer cells throughout the body. Most breast cancer cells metastasize to the lymph nodes. Goals of breast cancer treatment are:Regression of metastasesImprovement in symptoms and quality of lifeImprovement in survival timeThere isn’t a cure for metastatic breast cancer yetBalance toxicity of treatment with relief symptoms due to tumors There are 4 types of therapy for breast cancer:Endocrine therapyChemotherapyTargeted therapyImmunotherapy Factors deciding a certain therapy in metastatic breast cancer are:Patient ageMenopausal statusLevels of estrogen are much higher in premenopausal women than in postmenopausal womenGeneral healthTumor estrogen receptor (ER) status (and the less important progesterone receptor (PgR) statusEndocrine therapy is the preferred choice for ER+ metastatic breast cancer → has less side effects than chemotherapyTumor HER-2 statusTargeted therapy is the preferred choiceGood/poor responses to previous treatments Hormonal therapy is directed towards tumors which are hormonal dependent for their growth:Breast cancerEstrogen receptor positive (ER+)Prostate cancerTestosterone dependentEndometrial carcinomaProgesterone dependent Estrogen is a steroid which binds to the estrogen receptor on ER+ breast cancer cells → stimulates tumor cell growth. Approximately 60-70% of breast cancers express estrogen and/or a progesterone receptors. The goal of hormonal...

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Mechanisms of Disease 2 HC22: Chemoradiation

The therapeutic window can be increased by:Fractionation of the total doseDecreasing the toxicity → lower the dose to normal tissueIncreasing the tumor control → enhancing the sensitivityThe sensitivity can be enhanced via:ChemoradiotherapyRadiotherapy + chemotherapyBiological agentsCetuximab in head and neck cancerOxygen to tumor tissueIncreases the oxygen which reaches the tumor → high response rateDoesn’t really workHyperthermiaExposing tumor tissue to high temperaturesIn patients with cervical cancer and relapses of breast cancer Chemoradiation is a combination between radiotherapy and chemotherapy. This can be:Concomitant: in the same time periodSequential: behind each other If chemoradiation is used, DNA damage to tumor cells is more often fatal than with irradiation alone. Normal cells have a greater variety of escape mechanisms and repair the damage, which causes them to be more able to repair DNA than tumor cells → have a higher tolerance to the therapy. There are different modes of action for radiation and chemotherapy. Chemotherapy is used as a radiosensitizer which enhances the effect of radiotherapy. Chemo- and radiotherapy can be used to create synergy:Cisplatin adducts to DNA → causes single strand breaksRadiotherapy will create more breaks which are more difficult to repairPost-irradiation repair is inhibitedChemotherapy inhibits nucleotide metabolism, while radiation is effective in a different phase of the cell. Chemotherapy treats hypoxic cells, which are less radiosensitive for radiotherapy. Chemoradiation is seen as local treatment to increase local control and thereby cure. Chemoradiation is only used in curative treatment:As a primary treatment modalityOrgan saving treatmentCurative resection is not...

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Mechanisms of Disease 2 HC23: Normal hematopoiesis

Blood forms 8% of the total body weight, the other 92% consists of fluids and tissues. Blood is made up for 55% of blood plasma and for 45% of formed elements. Plasma is mostly made up of water, formed elements of red blood cells, white blood cells and platelets. Blood has many functions:Homeostasis: regulation of body temperature by plasmaBody supply: oxygen and nutrients supply by erythrocytes and plasmaWaste collection: of carbon dioxide and lactic acid by erythrocytes and plasmaDefense: anti-microbial and anti-tumor response by leukocytesCoagulation: by thrombocytes Erythrocytes form the largest fraction of blood cells → there are 5 x 1012erythrocytes per liter blood. They are red cells → cause the red color of blood. Erythrocytes can spend up to 120 days in the circulation. They have no nucleus and are fully differentiated → no proliferation takes place. Their function is oxygen transport.Erythrocytes contain hemoglobin:Males: 8,5-11,0 mmol/LFemales: 7,5-10,0 mmol/L The normal leukocyte count in blood is 4-10 x 109 per liter. Leukocytes can differentiate into:Granulocytes: have a life span of 1-2 daysNeutrophilic granulocytes1,5-7,5 x 109/LDefense against encapsulated bacteriaEosinophilic granulocytes<0,5 x 109/LMediate allergic responses and defense against parasitesBasophilic granulocytes<0,2 x 109/LMediate allergic responses and defense against parasitesLymphocytes: have a life span of days-yearsB-cellsAntigen-specific immune defenseAntibody productionCytokine secretionT-cells: CD4 T-cells and CD8 T-cellsAntigen-specific immune defenseCellular cytotoxicityCytokine secretionNK-cellsAntigen-independent defenseTumor surveillanceCytotoxic capacityMonocytes: have a life span of 12 hoursPhagocytosis...

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Mechanisms of Disease 2 HC24: Diagnostics in hematology

A 40-year-old man visits the GP with complaints of fatigue and pallor. The GP thinks the most likely clinical problem is anemia. The GP requests a complete blood count (CBC) → a differential count of Hb, leukocytes, and thrombocytes. Blood goes through an automatic hematology analyzer, a laser which gets scattered when it encounters a blood cell:Forward scatter/low angle: shows the volume of the cellSide scatters/high angle: shows the complexity of the cell (granules, MPC, etc)The machine is able to identify the cells based on size and complexity. The results are shown in a diagram, which makes it possible to determine how many and what kind of cells there are. Results of the CBC show:Hb: 4,3 mmol/L → too lowLeukocytes: 40 x 109/L → too highPlatelets: 70 x 109/L → too lowAcute leukemia is suspected. In leukemia, there are too many leukocytes compared to other cells. The diversity also is less. Microscopic leukocyte differentiation consists of a blood smear stained with May Grunwald Giemsa. In case of acute leukemia, differentiation of leukocytes is lost → many strange looking leukocytes which all look the same are present. There are several levels of diagnostics which make it possible to examine different structures:Resections/biopsies: tissueCytology: cellsMolecular pathology: molecules The bone marrow is the principle site of hematopoiesis. Examination of the bone marrow provides additional information for diagnostic clues seen in the peripheral blood:Increased or decreased leukocytesIncreased or decreased HbIncreased or decreased plateletsPresence of abnormal or immature cells Several diagnostic tests on the bone marrow tissue can be done:Standard histology: on tissue level...

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Mechanisms of Disease 2 HC25: Myeloid malignancies

Myeloid malignancies are divided into 3 categories:Disorders of proliferationChronic myeloid leukemiaMyeloproliferative disordersDisorders of differentiationMyelodysplastic syndromesDisorders of differentiation and proliferationAcute myeloid leukemia Chronic myeloid leukemia is a disorder of proliferation → it is a stem cell disease.= A 48-year-old male patient suffers from fatigue, but has no other complaints. Physical examination shows pallor and an enlarged spleen. A laboratory test shows:Hb: 8,0 mmol/L → too lowMCV (mean corpuscular volume): 96 fLLeukocytes: 113 x 10E9/L → too highPlatelets: 154 x 10E9/L → normalLeukocyte differentiation shows:1 promyelocytes10 myelocytes8 metamyelocytes8 band forms53 segmented neutrophilsThere shouldn’t be any promyelocytes, myelocytes and metamyelocytes present in the blood. The only cells that should be present are mature blood cells. The diagnosis is Philadelphia chromosome positive chronic myeloid leukemia (CML). The driver mutation of CML is BCR/ABL, caused by a translocation of chromosome 9 and 22. This mutation causes cells to have a proliferative advantage. There is no mutation in differentiation genes → differentiation in mature stages is normal. Therefore, neutrophils are segmented as usual. Chromosome 9 contains the ABL gene, chromosome 22 contains the BCR gene. The mutation takes place as follows:Both chromosomes breakThe ABL gene attaches to the BCR gene on chromosome 22 → the Philadelphia chromosome is createdA constantly active tyrosine kinase is madeMultiple substrates are phosphorylated → multiple ways of absent regulation are madeChronic myeloid leukemia arisesIt is unknown why the translocation of chromosome 9 and 22 occurs. There is no relation with exposition to...

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Mechanisms of Disease 2 HC26: Malignant lymphomas

There are 2 types of malignant lymphomas:T-cell lymphoma/NK-cell lymphomaB-cell lymphomaPluripotent hematopoietic stem cells (HSC) differentiate into:Common lymphoid precursor cells (CLP) → differentiate into:T-precursor cells → naïve T-cells → T-memory cellsB-precursor cells → B-memory cells or plasma cellsNK-cellsCommon myeloid precursor cells (CMP)By morphology alone, CLPs cannot be distinguished from CMPs → additional tests are necessary. A plasma cell is recognizable thanks to its big Golgi system. This is the only type of cell which can be distinguished by cell morphology alone. The difference between T-cells and B-cells can be made by looking at cell type specific antigens which are present on the cell:T-cells: CD3B-cells: CD19, CD20, CD79NK-cells: CD16/56 The primary purpose of lymphocytes is to recognize an antigen receptor. Precursor cells, like blast cells, do not have antigen receptor (AgR) expression yet → they are AgR negative. Both AgR positive and negative cells can cause neoplasia:Precursor neoplasia: caused by AgR negative cellsHave a blast-like morphologyMature neoplasia: caused by mature (AgR positive) cellsHave a lymphocyte/plasma cell morphologyIf mature cell receptors are destroyed, the cell goes into programmed apoptosis. This doesn’t happen in case of plasma cells, because they don’t have a receptor. There aren’t enough genes to code for the different type of receptors present in the adaptive immune system. This is solved by VDJ (IgH) and VJ (IgL) recombination:A B-cell precursor starts to express a receptor to become a B-cellThe B-cell precursor starts to cut out parts of DNA to form a functional gene → multiple V and J sequences are put together18 different combinations can be madeMore differentiation is possible by nibbling away...

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Mechanisms of Disease 2 HC27+28: Allogenic stem cell transplantation and donor lymphocyte infusion I&II

Hematopoietic stem cell transplantation (SCT) is performed because:It is a rescue procedure after a high dose of chemotherapy or irradiation to ensure hematopoiesisIt is a way to reset the immune systemIt replaces non- or dysfunctional bone marrowIt is an allogeneic cellular immune therapy for malignant disordersDisorders treated with autologous SCT are lymphoma and multiple myelomas. SCT is a form of cellular immunotherapy. A stem cell graft is harvested as follows:Filgrastim (neupogen) is injected subcutaneously into the patientG-CSF receptors are activated → cells migrate out of the bone marrow into the circulationA certain machine removes the cells which the patient doesn’t need, and returns the other cells back to the patient Autologous SCT is performed as follows:The stem cell graft is harvested from the patientCells are cryopreserved in liquid nitrogenThe patient is treated with high dose chemotherapy → results in ablation of the stem cells from the bone marrowThe stem cell product is reinfusedAll stem cell harvests contain a mixture of leukocytes: stem cells, T-cells, B-cells, NK-cells, monocytes and granulocytesThe actual treatment is the chemotherapy → stem cell transplantation only is a rescue procedure. The difference between allogeneic and autologous SCT is that in allogeneic SCT the graft of bone marrow cells is taken out of a healthy donor instead of the patient. Allogeneic SCT is performed as follows:A stem cell graft is harvested from the donorUsing G-CSF treatmentThe patient’s immune system and leukemia cells are destroyedImmune ablation of the patient is necessary to allow acceptance of donor cells → a stem...

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Mechanisms of Disease 2 HC29: HLA & minor histocompatibility antigens

There are 2 ways of doing an allogeneic SCT:Allogeneic SCT with T-cells present in the cell graft: transplantation of an immune system of a healthy donor with the aim to induce a strong T-cell response against the cancer cells of the patientMature donor T-cells in the stem cell transplant mediate GVL and GVHDSystemic immunosuppression is required to suppress GVHDSystemic immunosuppression is gradually decreasedAllogeneic SCT without T-cells present in the cell graftNo systemic immunosuppression is requiredConsists of 2 stepsT-cell depletion → no systemic immunosuppression is requiredDLI is necessary: 3-6 months after allogeneic SCT to induce GVLThe patient is in better conditionProfessional antigen-presenting cells of donor originLess pathogensLess inflammatory cytokinesThe T-cell response is weaker → better balance between GVL and GVHDThese patients do better as a group → lesser GVHD reactionThe body has time to heal damaged tissue from chemotherapyRecipient dendritic cells can be replaced by donor dendritic cells HLA molecules are located on chromosome 6. Per chromosome, there are 6 genes which play a role in HLA. Because humans have 2 chromosomes, there are 12 genes in total which play a role. There are 2 types of HLA molecules:HLA class I: present intracellular antigensHLA-AHLA-BHLA-CHLA class II: present endocytosed antigensHLA-DRHLA-DQHLA-DPThe HLA groups are located in the peptide binding groove. Only dendritic cells, macrophages and B-cells are capable of HLA-II expression. HLA is highly polymorphic → there are many variants and every different allele has its own name. Due to negative selection in the thymus of T-cells which have high affinity for HLA self-complexes, there are no T-cells for processing peptides derived from...

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Mechanisms of Disease 2 HC30: Changes in patients’ experiences

While patients experience cancer treatment as a unique life-changing series of events, to medical professionals it constitutes routine work practice. Joanna Baines wrote an article containing 3 stories of 3 generations of breast cancer:GrandmotherStayed at home after diagnosis, died at the age of 56For her, cancer was an experience of silenceMotherWas diagnosed with breast cancer at 35TreatmentRadical mastectomyRemoval of the entire breast, nipple, lymph nodes, vessels and muscles → severe and mutilating operationBecame less and less popular throughout the 1970sOvarian ablation throughout radiotherapy5 year follow up of remaining breast and glandsHardly received any information about her condition → saw cancer as an eventJoanna BainesDiagnosed with breast cancer at 32 years oldReceived several supplementary testsAbdomenLiverBonesTreatmentRemoval of the lump and lymph nodes in the armpitChemotherapy (5 months)RadiotherapyTamoxifen (5 years)HerceptinShe was part of an RCT (randomized control trial)Saw cancer as a part of her life A timeline of emerging cancer therapies has been created:1850-1920: radical surgery1900-1950: radiationMajor alternative to surgery before chemotherapyHigh energy radiation equipmentHuge machine surrounding the patientEmerged in the early 20th century1950-1970: chemotherapyEmerged after the WWII3 typesNitrogen mustardsDiscovered during WWIIDon’t produce lasting remissionHormonesIncreased use in the 1940s-1950sNow regarded as palliativeTamoxifen became available in the 1970s-1980sAntimetabolitesSydney Farber diagnosed ALL in a 2-year-old and injected him with aminopterin (an antifolic) → worked very wellDidn’t become the cure that everyone had hoped → only prolonged the lives for several monthsIssues...

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Mechanisms of Disease 2 HC31: Targeted therapy and hematological malignancies

CD20 is an IgG isotype expressed antigen on normal and malignant B-cells. It is used for treatment of many B-cell lymphomas → by targeting CD20 antigens, both malignant and normal B-cells are depleted. Chemotherapy combined with CHOP monoclonal antibodies leads to a significant increase of survival rates. Rituximab, a monoclonal antibody against CD20, leads to:Complement system activationA MAC is formedNK-cell recruitmentReceptors bind to the humanized tail of rituximabApoptosisMacrophages are attracted Monoclonal antibodies can have different mechanisms of action:Complement dependent cytotoxicity (CDC)The complement system is activatedHollow pipes are made in the cell surfaceWater enters the cellThe cell explodesAntibody dependent cellular cytotoxicity (ADCC)A B-lymphocyte plasma cell secretes antibodies which bind to an antigen on the pathogenThe pathogen is phagocytosed by macrophages, destroyed by NK-cells or lysed via the complement systemRadio immunotherapyA radioactive particle such as yttrium is coupled to an IgG monoclonal antibody such as CD20 → can get close to the tumor cellsA form of local treatmentYttrium gives a small dose of β- or γ-radiationThe tumor is directly targetedAntibody drug conjugateA drug is bound to a monoclonal antibody such as CD30 → an ADC-CD30 complex is createdCD30 is expressed in Hodgkin lymphomas and anaplastic large cell lymphomasThe ADC-CD30 complex travels to the lysosomeMMAE is released in the cell → disrupts the microtubule networkPhysical cell division is prevented by binding on a microtubule during cell divisionThe G2-/M-phase is arrested → the cell cycle stops → apoptosis Bispecific antibodies are a combination of 2...

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Mechanisms of Disease 2 HC32+33: Primary hemostasis

Thrombophlebtis is thrombosis due to infected vessels. Thrombotic events are the second leading cause of death in cancer patients, after death from cancer itself. The Trousseau syndrome describes the presence of thrombosis in relationship to cancer. Fibrin clots may be induced by cancerous processes:Cancer has an influence on coagulation → influences thrombosisCoagulation may have an influence on how the cancer will developThrombosis also has an effect on developing cancer. Patients with cancer have an increased risk for developing venous thrombosis:Odds ratio: 7Incidence: 24/1000/yearRisk and time since diagnosis of cancer0-3 months: odds ratio of 543-12 months: odds ratio of 1412-36 months: odds ratio of 4The Khorana risk score predicts the risk of cancer associated thrombosis. This risk differs per cancer type and patient:Site of cancerVery high risk → 2Stomach cancerPancreas cancerHigh risk → 1Lung cancerLymphomasGynaecological cancerBladder cancerTesticular cancerPrechemotherapy platelet count >350 x 109/L → 1Hemoglobin level 11 x 109/L → 1Body mass index >35 kg/m2→ 1These scores can be added to predict the risk:>3 → high risk1 or 2 → intermediate risk0 → low riskPatients with thrombosis also have a risk of developing cancer:Idiopathic (unprovoked) venous thrombosis: 10% of patients develop cancer in the next 3 yearsUnprovoked: thrombosis with no other clear causeProvoked venous thrombosis: 1,6% of patients develop cancer in the next 3 yearsSingle episode of superficial thrombosis: no clear association with cancerIf it returns, there is a connection Cancer and thrombosis are a very bad combination. Extensive screening can identify occult tumors, but this does not improve the survival...

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Mechanisms of Disease 2 HC34+35: Secondary hemostasis I&II

Blood flows as a fluid through the blood vessels to all the organ systems. Upon injury, blood vessel loss has to be prevented. This is done via blood coagulation. Under normal conditions, blood coagulation is a tightly regulated process:Rapid formation of a clot upon injuryLimited to the site of injurySecondary hemostasis is the conversion of soluble fibrinogen to insoluble fibrin by thrombin (IIa):Strengthens the platelet plugInduces adherence and activation of cells involved in vascular repairFibroblastsSmooth muscle cellsThrombin plays a key role in the conversion of fibrinogen to fibrin. It sometimes also is called coagulation factor IIa. Fibrinogen is also known as factor I and is very abundant in the plasma → normal levels are 1,5-3 gram/L. It consists of 2 symmetrical half-molecules, each consisting of 3 different polypeptide chains:Aα: linked together in the E-domain → the central partsBβ: in the D-domain → the outer partsγ: in the D-domain → the outer parts Fibrinogen is formed into fibrin as follows:Thrombin cleaves away fibrinopeptides A and B → fibrin monomers are formedFibrin monomers are very sticky2 fibrin monomers stick together → dimers are formedThis is done via H-bondsCoagulation factor XIIIa crosslinks different dimers → polymers are formedCoagulation FXIIIa = transglutaminaseThe enzyme factor XIII is converted into FXIIIa by thrombin (IIa)The crosslinks are formed between the D-domains of the fibrinThese are covalent bonds Thrombin is generated via the coagulation cascade. The coagulation cascade is a sequence of proteolytic reactions, which take place in parts of the surface of activated proteins. In each step, a pro-enzyme is converted to an enzyme, which activates the next pro-enzyme. These are slow reactions which can be sped up by co...

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Mechanism of Disease 2 HC36: Fibrinolysis and atherothrombosis

At some point, the platelet plug needs to be removed to return the normal blood flow.Fibrinolysis is part of the normal hemostasis. It enables repair of the injured vessel wall and is important in resolving an unwanted clot such as a thrombus.Fibrinolysis consists of the conversion of earlier formed fibrin, which is insoluble, into soluble fibrin degradation products. This process is important because it prevents venous thrombosis and atherothrombosis by removing unwanted clots. It is part of normal hemostasis. Plasmin is a molecule which degrades fibrin → after degradation, only D-dimers of fibrin are left:Cross-linked fibrin is degraded by fibrin degradation productsPlasmin cleaves the E-domainsD-dimers are formedA D-dimer is also a biomarker for the fact that thrombosis is present elsewhere. Plasmin generation consists of a sequence of proteolytic reactions on the surface of fibrin. There are 2 pathways, dependent of the activator:Pathway 1: tPA dependent plasmin generationActivator: tissue plasminogen activator (tPA)Produced by healthy endothelial cellstPA converts plasminogens to plasminsFibrin is the co-factor in his reaction → speeds up the reactiontPa is only active when bound to fibrin → advantageous in thrombosisIs the surface where tPA and plasmin react togetherPathway 2: uPA dependent plasmin generationActivator: sc-uPA or pro-urokinaseProduced by endothelial cells, macrophages and epithelial cellsPlasmin converts sc-uPA to tc-uPATc-uPA is the active form of sc-uPAtc-uPA converts plasminogen to plasmin → amplificationThe reaction takes place in both presence and absence of fibrin Plasmin generation is regulated by:Presence of tPA and uPAInhibitors of tPA, uPA and plasminPlasminogen activator inhibitor 1 (PAI-1)Produced by endothelium,...

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Mechanisms of Disease 2 HC37: Cancer, coagulation and thrombosis

Cancer leads to coagulation, which leads to thrombosis. Coagulation itself also leads to cancer, and thrombosis may as well. The link between cancer and thrombosis was established almost 200 years ago by Jean-Baptiste Bouillaud and Armand Trousseau. Trousseau diagnosed himself with thrombosis and predicted he suffered of cancer. Months later, he indeed died of pancreatic cancer. Cancer and thrombosis are a dual clinical problem. Out of 7 million cancer-associated deaths, 1 million are attributed to thrombotic complications. Patients with cancer and thrombosis have an extremely bad prognosis. The second main cause of death in cancer patients is deep venous thrombosis/pulmonary embolism (VTE):25% of all first VTE events are cancer-relatedThe presence of malignancy results in a 7x increased risk of VTE0-3 months after cancer diagnosis: 54x increased risk3-12 months after cancer diagnosis: 14x increased risk12-36 months after cancer diagnosis: 4x increased risk8% of all cancer patients experience VTEThe risk of developing VTE in case of cancer can be divided into 2 groups:Clinical risk factorsBiological risk factors Not all cancer types confer the same risk for VTE. Patients with pancreas, lung and/or brain cancer have the highest incidence rate of VTE. The more aggressive the tumor, the higher the risk. The risk of VTE reflects the stage of the disease → in remote cancers, the risk of VTE is highest. Certain cancer treatments can increase the risk of VTE as well:Surgery: 2x increased risk of VTE in cancer patientsChemotherapy: the risk variesNew antiangiogenic drugsProlonged bed restTreatment of venous thrombosis in cancer patients usually consists of low molecular weight heparin (LMWH), which is more effective than vitamin K agonists. LMWH...

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Mechanisms of Disease 2 HC38: Bleeding disorders

A bleeding disorder can roughly have 3 different causes:Decrease in procoagulant factorsFactor VIIIFactor IXFactor VUse of anticoagulant medicationVitamin K antagonistsDirect oral anticoagulantsDisorders such as liver failure, leukemia or immune thrombocytopeniaBleeding disorders can be congenital or acquired:Congenital disordersHemophiliaVon Willebrands diseasePlatelet disordersDeficiencies of other clotting factorsAcquired disordersLiver failureHaematological diseasesAutoimmune diseasesImmune thrombocytopeniaAcquired hemophiliaDiffuse intravascular coagulationUse of medicationVitamin K antagonistsDirect oral anticoagulantsThrombocyte aggregation inhibitorsAspirinClopidogrel Bleeding disorders are analyzed based on:Patient historyCongenital versus acquiredType of bleedingSiteMucosalSkinGumsNosebleedsMenstrual bleedingJoints musclesWhen it startedSpontaneousAfter traumaAfter surgeryTooth extractionsOther diseasesUse of medicationFamily historyPhysical examinationSigns of bleedingHaematomaPetechiaeRed spots under the skinBleeding in joints or musclesE.g. swollen kneesSplenomegaly or lymph node enlargementThese are signs of hematological malignanciesSkin abnormalitiesAtypical eczema can be the cause instead of bleeding disordersGeneral laboratory investigationsHb and thrombocyte countProthrombin time (PT)APTTFibrinogenLiver and kidney function testsSpecific laboratory investigationsBleeding timePlatelet function analyzer (PFA)Platelet aggregation testsMeasurement of individual coagulation factorsFVIII, IX, V, VII, II, X, XI, XII, XIIIMeasurement of fibrin degradation productsD-dimersInhibitor assays In case of von Willebrands disease (VWD), there is an abnormality in both primary and secondary hemostasis. The...

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Mechanisms of Disease 2 HC39: Thrombosis

Thrombosis is caused by a decrease in anticoagulant factors. Deep vein thrombosis (DVT) has the following symptoms:Red skinWarmPainful calfSwellingShining skinPain while walkingIn 40% of cases with suspected DVT, the clinical diagnosis is correct. Ultrasounds of the vessels in the leg are primarily used to diagnose DVT. In normal situations, the vein compresses and becomes hard to see. In case of thrombosis, the vein doesn’t become compressed as much. DVT differs from arterial thrombosis because it occurs at sites of stasis. Post thrombotic syndrome (PTS) is a persistent swollen and painful leg as a result of DVT. Symptoms are:Swollen legHeavy feeling legPainVaricose veinsDiscoloration of the skinUlcerationIn post thrombotic syndrome, accumulation of thrombotic platelets causes a leaky valve. Current treatment to prevent the development of post-thrombotic syndrome consists of compression stockings → the venous pressure is increased. A pulmonary embolism (PE) is an embolization of a venous thrombus into the pulmonary artery. Symptoms are:BreathlessnessPleural painHemoptysisFeverShockA very deadly form of pulmonary embolism is a saddle embolism → almost always results in death. Diagnosis of pulmonary embolism requires objective imaging:CT-scansAre primarily usedWhite contrast fluid is injected → gray areas show blood clotsChest X-raysIn acute phases of pulmonary embolismsRules out other diseases mimicking pulmonary embolismAfter a few days, pulmonary infiltrates may become visible → infarctsVentilation-perfusion scan: shows radioactivity in the lungs → if there is radioactivity, no blood is presentPerfusion: intravenous injection of radioactive technetium macro-aggregated albuminTc99m-MAAVentilation: inhalation of gaseous radionuclides in aerosolXenon-133Pulmonary...