Principles of anticancer drug therapy Flashcards
What is chemotherapy?
tx of cancer with drugs
interfere with cell growth/division
action is not specific, destroy all rapidly dividing cells
What are some types of chemotherapy indications?
induction chemo: induce a remission
consolidation chemo: sustain a remission for longer
adjuvant chemo: administered in the microscopic setting
neo-adjuvant chemo: administered in macroscopic setting to shrink for easier surgery
maintenance chemo: maintain remission (controversial)
re-induction chemo: re-introduce induction protocol
rescue chemo: if patient is out of remission/ initial drugs given are failing
In what cases do we decide on chemotherapy?
tx of disseminated disease: lymphoma, multiple myeloma, leukemia, MCT, histiocytic disease
adjuvant following surgical resection in case of: incomplete excision, metastasis, high malignancy
neo-adjuvant to reduce tumour size prior to sx or RT
transmissible venereal tumour
When should we administer chemotherapy?
as early as possible: unlikely effective in macroscopic and end-stage dz
as early as possible post surgery: 10-14 days, prioritose wound healing and recovery first
How do we decide on chemotherapy doses?
aim for greatest fractional cell kill with each tx
dosing for body surface area (mg/m2)
multiple doses, pulse dose at intervals (normal tissue recovery, prevent tumour regrowth)
can’t kill tumour with one dose
What is the maximum tolerated dose in chemotherapy?
a fixed dose kills off a fixed percentage of cells rather than a number of cells
How does tumour cell number change over time with chemo therapy?
will decrease at each dose
but normal for a small increase before next tx
What is combination chemo and why is it used?
combination protocols often more effective
use drugs that are effective as single agents, have different modes of action thaat don’t interfere and avoid overlapping toxicities`
What is metronomic chemotherapy?
administration of regular low, daily dose of cytotoxic agents (usually tablet)
targets the microenvironment: blood vessels feeding the cancer cells, +/- less side effects
usually in very palliative cases: keeps cancer stable
What are the alkylating agent chemotherapy drugs?
cyclophosphamide
lomustine
chlorambucil
melphalan
What are the vinka alkaloid chemotherapy drugs?
vincristine
vinblastine
vinorelbine
What are the antimetabolite chemotherapy drugs?
cytarabine
gemcitabine
methotrexate
5-FU
What are the platinum agent chemotherapy drugs?
carboplatin
What are the anti-tumour antibiotic chemotherapy drugs?
doxorubicin
epirubicin
mitoxantrone
Why is prednisolone sometimes used as a chemotherapy drug?
apoptosis of lymphoid cells (lymphoma, leukaemia)
apoptosis of mast cells (MCT)
but high doses in cancer ptx = ++ adverse effects: PU/PD, panting, muscle wastage
Why are NSAIDs sometimes given as chemotherapy drugs?
cox-inhibition vs cancer progression
anti-angiogenic
promote apoptosis
anti-infl.
analgesic
indications: transitional cell carcinoma, other carcinomas and sarcomas
What is more susceptible to adverse effects of chemotherapy?
normal tissues with rapidly dividing cells
- myelosuppression
- GI toxicity
- hair loss
- drug extravasation
- cardiotoxicity
- sterile haemorrhagic cystitis
What are signs of myelosuppression?
neutropenia: nadir (lowest pt) around 7days post-chemo)
thrombocytopenia: nadir around 10 days post-chemo
monitor CBC prior to each tx
How can we manage myelosuppression?
Monitor CBC prior to each tx
delay + retest if neutropenic in 3-7 days depending on severity
ABs if low neutrophil count or neutropenia + febrile (IV ABs hospitalised)
consider dose reduction
How can we prevent/manage GI toxicity?
antiemetics as prevention
ABs if haemorrhagic diarrhoea or persistent diarrhoea (other causes excluded)
antiemetics, gut protectants, anti-diarrhoeal medication
When is hair loss an adverse effect?
breed disposition!
alopecia only, loss of whiskers
How can we prevent drug extravasation?
clean placed catheter
firmly taped in
flush with saline
How do we treat drug extravasation?
try aspiration of drug
vincristine: hot compresses, hyaluronidase
doxorubicin: ice, dexrazoxane
How can we prevent sterile haemorrhagic cystitis?
monitor
access to water
furosemide
How can we treat sterile haemorrhagic cystitis?
stop medication
analgesia
instillation of DMSO, glycosaminoglycans
What are the signs of sterile haemorrhagic cystitis?
haematuria and stranguria - culture negative
What are chemotherapy drugs we should never administer to cats as they are fatal?
cisplatin (pulmonary oedema)
5-fluorouracil (neurotoxicity)