Dunedin-Oncology Flashcards
Describe some oncogenes
Describe some tumour suppressor genes
What is micro satellite instability (MSI)?
genetic hypermutability that occurs with impaired mismatch repair (MMR)
What does MSH2 and MLH1 bind to?
4 main proteins but 2 main complexes
MSH2 —> attach to MSH6
MLH1 attach to PMS2
MSH6 and PMS2 do not have alternatie binding partners, so id you lose MLH1 and MSH2 then you loose both
What is the inheritance mode of Lynch syndrome?
autosomal dominant
mutations in one of the 5 key MMR genes: MLH1, MSH2, MSH6, PMS2, EPCAM
What is the action of CTLA4?
What is the action of PDI?
CTLA4: Dampens the amplitude of the immune response
PD1: down regulates the activity of T cells (tumour)
What are the mechanisms of metastatic spread?
- Haematogenous spread
- Lymphatic spread
- Transcoelomic spread- direct seeding of peritoneal/pleural cavity
What are some blood tests used for staging of cancer?
- LDH – melanoma
- hCG – gestational trophoblastic tumours
- LDH, hCG, AFP - testis
What is the therapeutic targeting for cancer?
Describe the cell cycle
G1- cellular contents duplicated
S- chromosomes duplicated
G2- double check of chromosomes
Mitosis
cytokinesis
Describe the S-Phase of cell cycle
DNA unraveling from histones (HDAC inhibitors)
Helicase splits DNA double strand
Topoisomerase “release tension” of unwinding helix (topoisomerase poisons)
DNA polyemerase assist matching of base pairs (Purine and pyrimidine analogues)
Ligase joins short fragments and completes replication
Describe Mitosis
Classes of chemotherapies?
Alkylating agents - mustards, platinums
Anti-metabolites- anti-folates, purine analogues, pyrimidine analogues
Alkaloids and topoisomerase poisons
Hormones
What are the types of Alkylating agents?
Mustard and derivatives
Cyclosporin / Cyclophosphamide
* Chlorambucil
* Dacarbazine
* Temozolomide
* Lomustine
* Streptozotocin
Platinum agents
* Cisplatin
* Carboplatin
* Oxaliplatin
What is the MOA of alkylating agents
Work at any point in the cell cycle
Mustard: Addition of ethyl or methyl groups to various positions on DNA bases e.g. cyclophosphamide
Platinum: cause cross linking of DNA preventing helicase separating double strand, preventing replication
What is the MOA of anti-metabolites
Act only in S phase
Work by interfering with T G C A (U) synthesis
Interfere with DNA and RNA production
What are the types of anti-metabolites?
anti-folates: methotrexate
Purine antagonist: Fludarabine, azathioprine, 6-TG
pyrimidine antagonis: fluropyrimidines, gemcitabine
What are examples of alkaloids? and its MOA
Vinca alkaloids- vincristine, vinblastine, binorelbine
Stop microtubule formation
Taxanes- paxlitaxel, docetacel
stops microtubule disassembly
Topoisomerase inhibitor: s-phase specific
What is the MOA of anthracyclines
Non-cell cycle specific
interfere with toposomerase 2
induce histone vision from chromatin
Eg doxorubicin, daunorubicin, epirubicin
Describe some oestrogen signalling axis and inhibitors
LHRH analogues- lucrin, zoladex
Tamoxifen - SERM
Aromatase inhibitors: anastrozole, letrozole
Steroidal aromatase inhibitors - exemestane
Describe some androgen signalling axis and inhibitors
LHRH analogies - lucre, zoladex
peripheral androgen blockage (bicalutamide, flutamide)
Adrenal androgen synthesis (abiraterone)
What are main S/E of chemotherapy?
What pathways are involved in angiogenesis?
VEGF, FGFR, PDGFR
What pathways are involved in epidermal growth factor receptor pathway?
HER2(EGFR2)
* PI3-AKT-mTOR signaling pathway
* RAS-RAF-MEK-ERT signaling pathway
Nomenclature of monoclonal antibodies
What are common side-effects of EGFR pathway?
dermatological toxicity
What are common side effects of VEGF pathway?
hypertension, impaired wound healing, GI perforation (monoclonal antibodies – also proteinuria)
Describe the epidemiology of Colorectal cancer
2nd/3rd most common cancer
2nd most common cause of cancer death
Describe risk factors for colorectal cancer
Risks:
* Personal/Family history
* Ulcerative colitis
* Hyperinsulinism: RR 1.30
* Alcohol:>2pints/d,4glasseswine/d:RR1.41
* Obesity: RR 1.5 if BMI > 25
* Vitamin B6 inversely related to colon cancer
risk: RR 0.51
* Unclear whether supplementation or diet important
* Exercise: RR 0.33-0.60
* Diet – Western Diet
* Red meat > 300g / week -harmful
calcium protective
What are the 3 main molecular subtypes of colorectal cancer?
CIN (APC pathway, classical): Chromosome instability
MSI-H (Lynch/HNPCC or BRAF): Microsatellite instability
CIMP: CpG island methylator phenotype
What is the genetic mode of HNPCC/Lynch syndrome?
autosomal dominant
What is the genetic mode of familial adenomatous polyposis
autosomal dominant
What is the most typical phenotype of HNPCC
right sided, <50, microsatellite instability
What is MUTYH- associated polyposis?
Phenotypically like FAP or attenuated FAP, but no APC mutn.
Homozygous MUTYH mutation. AR.
Estimated 1 in 100 carrier rate.
What is the age range for FOBT screening?
biennial, age 45-70
What microorganism is associated with bowel cancer?
Strep gallolyticus (AKA strep bovis)
Can CEA be falsely elected in smokers?
Yes
What polyp carries the highest likelihood of malignancy?
tubulovillous adenoma with low grade dysplasia