13. Cancer Chemotherapy Flashcards
What is the length of time of cell proliferation in cancer cells?
9-43 hrs
What is growth fraction?
Proportion of cells dividing at any given time
Useful indicator of sensitivity to chemotherapeutic agents
What is the mechanism of action of alkylating agents?
Form covalent bonds with cell constituents
Reactive intermediate is carbonium ion
Many have 2 alkylating groups so can form cross links leading to defective DNA replication
What is the mechanism of action of platinum compounds?
Formation of platinated inter and infra strand adducts, leading to inhibition of DNA synthesis
How does 5-fluorouracil work?
Inhibits thymidylate synthase, no formation of DNA
How does methotrexate work?
Competitively inhibits dihydrofolate reductase (critical enzyme in folate cycle), no DNA synthesis
What are the mechanisms of resistance in alkylating agents?
Decreased entry or increased exit of agent
Inactivation of agent in cell
Enhanced repair of DNA lesions produced by alkylation
What can affect the distribution of chemo?
Weight loss
Reduced body fat
Ascites
What may interact with capecitabine?
Warfarin
St Johns wort
Grapefruit juice
What can interact with methotrexate?
Penicillin
NSAIDs
What are some adverse effects of chemo?
Acute renal failure
GI perforation at site of tumour
Disseminated intravascular coagulopathy
How is the response of the cancer in chemo monitored?
Radiological imaging
Tumour marker blood tests
Bone marrow/cytogenetics
