Cancer Chemotherapy Flashcards
What is the fractional cell kill hypothesis?
The balance between tumour cells and bone marrow cells, used to help decide when to give next chemotherapy treatment. Chemotherapy hits both tumour cells and normal cells but bone marrow cells return to normal quicker than tumour cells - therefore want to give next dose of chemotherapy when bone marrow cells are normal but tumour cells are still low.
Name a cancer that is highly sensitive to chemotherapy, moderately sensitive and has low sensitivity.
Highly sensitive - lymphomas, neuroblastoma
Moderately sensitive - breast, cervical
Low sensitivity - prostate, renal cell
Name the 3 categories of chemotherapy drugs.
1) alkylating agents
2) antimetabolites
3) spindle poisons
Name an alkylating agent used for chemotherapy and its MOA of action.
Cisplatin (platinum compound)
Attaches an alkyl group to DNA, leads to DNA damage and inhibition of DNA synthesis.
Name 2 antimetabolites used for chemotherapy.
Methotrexate
5-fluorouracil
What is the mechanism of action of methotrexate when used for chemotherapy?
Inhibits dihydrofolate reductase (enzyme in folate pathway) - inhibits cell growth and division as you need folate to make purines.
What is 5-fluorouracil used for and what is its mechanism of action?
Chemotherapy
Inhibits thymidylate synthase enzyme (enzyme in folate pathway) - inhibits cell growth and division as folate is needed to produced purines.
Which DNA bases are purines and which are pyrimidines?
Purines (2 rings) - adenine, guanine
Pyrimidines (1 ring) - cytosine, thymine, uracil
Name the 2 types of spindle poisons used for chemotherapy and the mechanism of action of each.
- vinca alkaloids e.g. Vincristine - inhibit microtubule assembly
- taxanes e.g. Paclitaxel - inhibit microtubule polymerisation
What is the most common route of administration for chemotherapy?
IV - through a PICC line (in the arm) or Hickman line (in the chest).
Side effects of chemotherapy are very systemic (affect the whole body), why is this?
Because chemotherapy targets any organ system that has dividing cells.
What is the mechanism of action of spindle poisons in chemotherapy.
Inhibit normal microtubule function, interrupting mitosis.
How can chemotherapy lead to peritonitis?
If the tumour is in the GI tract, a hole can be left after the tumour dissolves, if food gets into the peritoneum through this hole then you can get peritonitis.
State the main side effects of chemotherapy.
- renal failure
- vomiting
- alopecia
- skin toxicity - local irritation or thrombophlebitis (clot formation in veins)
- lung toxicity - pulmonary fibrosis
- mucositis - sore mouth/thorat, diarrhoea, GI bleeds or oral thrush
- myelosuppression
How can chemotherapy lead to renal failure?
Rapid tumour lysis leads to release of lots of toxins such as urea. Hyperuricaemia can lead to urate crystals forming in the kidneys, causing renal failure.
