Chemotherapy - Indications, Administration + MoA Flashcards
How do most chemotherapies work?
-Most target DNA (directly or indirectly)
-Preferentially toxic towards actively proliferating cells, so tumours which divide rapidly respond best to chemo
When is neoadjuvant chemotherapy used?
-Pre-operatively before intervention
-Aiming to make tumour smaller, allow less radical surgery, and treating occult micro-metastases
-Used for osteosarcoma, trialled for breast cancer
-Aims to cure patients
When is primary chemotherapy used?
-Initially used for a tumour that is inoperable / of uncertain operability, where a reduction in tumour size may make surgery more feasible
-Aims to increase cure rates
When is adjuvant chemotherapy used?
-Given following complete macroscopic clearance from surgery
-Treats occult microscopic mets in lymph-node positive disease to prevent relapse
-Aims to increase cure rates
When is palliative chemotherapy used?
-Given to alleviate symptoms or prolong life in patients that cannot be cured
-Must be balanced with QoL
When is curative chemotherapy used?
-Often more intensive treatment in cases of significant chances of cure
-Often more toxic
When is prophylactic chemotherapy used?
-Hormonal treatments given before overt malignancy is found eg tamoxifen for in-situ breast cancer before invasive carcinoma is recognised
Why does chemotherapy involve a combo of different drugs?
-Different classes have different actions so work synergistically to kill more cells
-Reduces chance of drug-resistant malignant cells emerging
-Can maintain dose with drugs that have different toxicity sites
How is chemotherapy administered?
Cyclically every 3-4 weeks
Maximum response seen after a 6-month course
What routes of administration are there for chemotherapy drugs?
ORAL
-Reduces hospital visits / no invasive procedure required
-Only a minority of drugs are available to be taken PO (tamoxifen, cyclophosphamide)
SYSTEMICALLY
-ie IV via blogs injection or short infusion
-Some may be given continuously via a central line
REGIONALLY
-Intra-vesical - superficial bladder cancer
-Intra-peritoneal - trans-coelomic tumours eg spread from ovarian cancer
-Intra-arterial - any tumour that has a well-defined blood supply eg liver mets
How is the appropriate dose of chemotherapy calculated?
-Using patient’s body surface area (BSA)
-Exception = carboplatin dose is calculated directly according to the renal function