Cancer Investigations and Treatments

Question 1

which chemotherapy drugs act during the S phase of the cell cycle? (DNA replication phase)

Answer 1

antimetabolites e.g. MTX
anthracycline Abx e.g. daunorubicin, doxorubicin
nucleotide analogues e.g. cytarabine-used to treat AML.

Question 2

what part of the cell cycle do alkylating agents target?

Answer 2

e.g. cyclophosphamide

act at ALL stages of the cell cycle

Question 3

which chemotherapy drugs act during mitosis?

Answer 3

vinca alkaloids e.g. vincristine
taxanes e.g. paclitaxel, docetaxel
=spindle poisions

Question 4

mechanism of action of anthracycline antibiotics in chemotherapy treatment?

Answer 4

these act during S phase of cell cycle
they are topoisomerase inhibitors-an enzyme that normally unwinds DNA, which is necessary for DNA replication.
e.g. doxorubicin

Question 5

mechanism of action of vinca alkaloids?

Answer 5

e.g. vincristine
act during mitrosis
antimicrotubule agents which interfere with spindle formation so chromosomes are unable to be separated.

Question 6

name a group of chemotherapy drugs known to be associated with the ADR of peripheral neuropathy and explain why this happens.

Answer 6

vinca alkaloids e.g. vincristine
these are antimicrotubule drugs and microtubules are required for the preservation of normal structure of long sensory axons in the NS.

Question 7

how does resistance to chemotherapy develop?

Answer 7

increased drug efflux-via p-glycoprotein-a cell surface channel whose expression is increased with MDR-1 gene overexpression.
reduced drug uptake e.g. altered folate receptor-MTX resistance
increased catabolism/detoxification
alteration of drug target eg. topoisomerase II mutations-so can no longer be inhibited by anthracycline Abx e.g. daunorubicin.

Question 8

role of combination chemotherapy?

Answer 8

to optimise benefit of chemotherapy treatment and minimise toxicities
to reduce the emergence of resistance

Question 9

what is the immediately life threatening risk of tumour lysis syndrome?

Answer 9

hyperkalaemic induced cardiac arrhythmia causing cardiac arrest

Question 10

what electrolyte is decreased in tumour lysis syndrome?

Answer 10

Ca2+

Question 11

drug treatment of tumour lysis syndrome?

Answer 11

allopurinol-xanthine oxidase inhibitor so inhibits the production of uric acid by inhibiting xanthine production
rasburicase-recombinant form of urate oxidase which increases uric acid breakdown.

Question 12

what is imatinib, what is it used to treat?

Answer 12

small molecule inhibitor, used in the treatment of CML
acts against a specific fusion protein-Bcr-Abl, which is enzyme necessary for the maintenance of the leukaemia and is specific to it. prevents substrate phosphorylation by the enzyme.

Question 13

define immunotherapy

Answer 13

the use of monclonal Abs to stimulate the body’s own immune system to fight the cancer.

Question 14

give an example of immunotherapy that can be used in the treatment of advanced melanoma

Answer 14

ipilimumab
this is an anti CTLA4 Ab-CTLA4 is found on the surface of T cells and as it is blocked, all T cell interactions have to occur via the CD28 protein which results in T cell activation and so ability of the IS to fight the Ca.

Question 15

define neoadjuvant chemotherapy

Answer 15

chemotherapy given before the definitive tment (usually surgery) to reduce the size of the tumour and/or increase likelihood of cure

Question 16

define adjuvant chemotherapy

Answer 16

chemotherapy given after the definitive treatment to eliminate any subclinical disease.

Question 17

examples of cancers treated with taxanes?

Answer 17

breast Ca-metastatic
lung Ca
prostate Ca-in hormone refractory locally advanced or metastatic disease
stomach Ca
head and neck Cas

Question 18

give examples of cancers treated with radiotherapy and the number of sessions the pt is treated with

Answer 18

breast Ca-40 Gy (gray)-the absorbed dose of radiation, and this total is achieved over 15 sessions (5 days a week for 3 weeks), so 2.67 Gy each session.
prostate Ca-37-39 sessions, almost 8 weeks of treatment.

Question 19

what is meant by a treatment cycle in chemotherapy?*

Answer 19

length of time between chemotherapy treatment sessions that allows adequate tissue recovery time.

Question 20

what is the WHO classification of performance status?

Answer 20

this is a means of measuring patient fitness to help guide appropriate treatment in patients with cancer
0=able to carry out all normal activity without restriction
1=restricted in strenuous activity but ambulatory and able to carry out light work
2=up and about more than 50% of waking hrs, ambulatory and capable of all self-care but unable to carry out work activities
3=in a chair or bed for more than 50% of the day, symptomatic but not bedridden
4=completely disabled, confined totally to bed or chair, cannot carry out any self-care.

Question 21

why does chemotherapy cause a sore mouth and ulcers?

Answer 21

GI tract mucosa consists of rapidly proliferating cells which are hence targeted by the chemotherapy.

Question 22

What is a PET scan? Why is it useful?

Answer 22

PET=positron emission tomography
type of scan relying on glucose metabolism by the tumour as the means of detecting tumour sites.
substance very similar to glucose (deoxyglucose) is labelled with radioactive tracer-forms FDG, injected IV. As similar to glucose, taken up by those areas of the body which are highly metabolically active, including the tumour cells. As the FDG is broken down, positrons are released which are radioactively labelled and these are detected.