Principles of anticancer drug therapy

Question 1

What is chemotherapy?

Answer 1

tx of cancer with drugs
interfere with cell growth/division
action is not specific, destroy all rapidly dividing cells

Question 2

What are some types of chemotherapy indications?

Answer 2

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

Question 3

In what cases do we decide on chemotherapy?

Answer 3

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

Question 4

When should we administer chemotherapy?

Answer 4

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

Question 5

How do we decide on chemotherapy doses?

Answer 5

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

Question 6

What is the maximum tolerated dose in chemotherapy?

Answer 6

a fixed dose kills off a fixed percentage of cells rather than a number of cells

Question 7

How does tumour cell number change over time with chemo therapy?

Answer 7

will decrease at each dose
but normal for a small increase before next tx

Question 8

What is combination chemo and why is it used?

Answer 8

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`

Question 9

What is metronomic chemotherapy?

Answer 9

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

Question 10

What are the alkylating agent chemotherapy drugs?

Answer 10

cyclophosphamide
lomustine
chlorambucil
melphalan

Question 11

What are the vinka alkaloid chemotherapy drugs?

Answer 11

vincristine
vinblastine
vinorelbine

Question 12

What are the antimetabolite chemotherapy drugs?

Answer 12

cytarabine
gemcitabine
methotrexate
5-FU

Question 13

What are the platinum agent chemotherapy drugs?

Answer 13

carboplatin

Question 14

What are the anti-tumour antibiotic chemotherapy drugs?

Answer 14

doxorubicin
epirubicin
mitoxantrone

Question 15

Why is prednisolone sometimes used as a chemotherapy drug?

Answer 15

apoptosis of lymphoid cells (lymphoma, leukaemia)
apoptosis of mast cells (MCT)

but high doses in cancer ptx = ++ adverse effects: PU/PD, panting, muscle wastage

Question 16

Why are NSAIDs sometimes given as chemotherapy drugs?

Answer 16

cox-inhibition vs cancer progression
anti-angiogenic
promote apoptosis
anti-infl.
analgesic

indications: transitional cell carcinoma, other carcinomas and sarcomas

Question 17

What is more susceptible to adverse effects of chemotherapy?

Answer 17

normal tissues with rapidly dividing cells

• myelosuppression
• GI toxicity
• hair loss
• drug extravasation
• cardiotoxicity
• sterile haemorrhagic cystitis

Question 18

What are signs of myelosuppression?

Answer 18

neutropenia: nadir (lowest pt) around 7days post-chemo)

thrombocytopenia: nadir around 10 days post-chemo

monitor CBC prior to each tx

Question 19

How can we manage myelosuppression?

Answer 19

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

Question 20

How can we prevent/manage GI toxicity?

Answer 20

antiemetics as prevention

ABs if haemorrhagic diarrhoea or persistent diarrhoea (other causes excluded)
antiemetics, gut protectants, anti-diarrhoeal medication

Question 21

When is hair loss an adverse effect?

Answer 21

breed disposition!

alopecia only, loss of whiskers

Question 22

How can we prevent drug extravasation?

Answer 22

clean placed catheter
firmly taped in
flush with saline

Question 23

How do we treat drug extravasation?

Answer 23

try aspiration of drug
vincristine: hot compresses, hyaluronidase
doxorubicin: ice, dexrazoxane

Question 24

How can we prevent sterile haemorrhagic cystitis?

Answer 24

monitor
access to water
furosemide

Question 25

How can we treat sterile haemorrhagic cystitis?

Answer 25

stop medication
analgesia
instillation of DMSO, glycosaminoglycans

Question 26

What are the signs of sterile haemorrhagic cystitis?

Answer 26

haematuria and stranguria - culture negative

Question 27

What are chemotherapy drugs we should never administer to cats as they are fatal?

Answer 27

cisplatin (pulmonary oedema)
5-fluorouracil (neurotoxicity)