Chemotherapy Flashcards
What is the fractional cell kill hypothesis?
Chemo kills tumour cells as well as bone marrow cells
Both have the oppurtunity to repair themselves
Bone marrow recovers faster than tumour cells
So you need to give bone marrow enough time to grow back but not the tumour cells
This means you don’t wipe out bone marrow but you get a gradual reduction in tumour cells
What tumours are highly sensitive to chemotherapy?
Lymphoma
Germ cell tumours
Neuroblastoma
What tumours have a moderate sensitivity to chemotherapy?
Breast
Colorectal
Bladder
What tumours have a low sensitivity to chemotherapy?
Prostate
Renal cell
Brain tumours
What is the optimal treatment for cancer? And how can chemo be involved here?
Surgery cures most cancers
Chemo mops up leftover tumour cells (only takes one for it to grow back)
How do alkylating agents work?
Inhibit transcription of DNA to RNA, therefore stopping protein synthesis
Substitute alkyl groups for hydrogen atoms on DNA
- this forms cross links, so that DNA can’t unravel to replicate
Affects cancer cells the most because they divide very rapidly
How do Platinum compounds work?
Adds sub groups which are bulky and interrupt with replication
Pushes cancer cells towards apoptosis
How do anti-metabolites work?
Similar to precursors of DNA synthesis
Interfere with purine and pyrimidine production
How do spindle poisons work?
Inhibit depolymerization of spindle microtubules at metaphase
Stops cancer cell division
How can cancer cells develop resistance to chemo?
- decreased entry or increased exit of the agent
- inactivation of agent inside the cell
- enhanced repair of DNA lesions produced especially by alkylation
What do you have to consider when prescribing chemo?
Performance score
- 0-5 (fine to dead)
- patients with a higher score are less likely to be able to tolerate chemo
So there’s no point giving chemo to someone who’s going to die anyway as you’ll decrease their quality of life
However if they’re more likely to benefit from it in the long term then it is worth it
What are some side effects of chemo? (See notes for more)
Alopecia Mucositis Nausea and vomiting Diarrheoa Sterility
How can chemo lead to acute renal failure?
Hyperuricaemia is caused by tumour lysis
This leads to precipitation of urate crystals in renal tubules
What causes variability between patients responses to chemo?
Abnormal in absorption, distribution, elimination and protein binding
What drugs increase chemo action?
Vincristine Warfarin Methotrexate St. John's Wort Grapefruit juice
