17 - Principles of Cancer therapy

Question 1

Clinical Presentation of cancer

Answer 1

Primary tumour
- local effects due to expansion, breach of epithelial surfaces, narrowing of body tubes, invasion of local structures

Metastasis
-distant effects , involving lymph nodes, lungs, brain ect.

Paraneoplastic syndromes
-Generalised effects - due to hormonal, autoimmune or undefined mechanisms

Question 2

Cancer diagnosis and investigation

Answer 2

Diagnosis - tumour biopsy, histopathology

Staging - Determination of extend of involvement

Functional assessment - how patient is likely to cope with disease and treatment

Question 3

Radiation Therapy - 2 modes and way it works

Answer 3

Ionising radiation - mode of cell death
-energy from radaition damages DNA and generates free radicals that damage water, proteins and organals

Therapeutic Radiotherapy
-external beam radiotherapy

Question 4

Chemotherapy vs drug therapy

and selective toxicity

Answer 4

Uses chemicals to kill disease causing cells in body (e.g bacteria, fungi, viruses, cancer)

Drug therapy - uses chemicals to modulate body processes (e.g blood pressure)

Selective toxicity - occurs wen toxicity is produced in the cancer cell without effects in host cells (exploits differences between normal cells and disease producing cells )

Question 5

Therapeutic index

Answer 5

Important indicator of selective toxicity

Ratio of dose required to produce toxic effect divided by dose required to produce desired effect

TI = ED50 for unwanted toxicity / ED50 for therapeutic activity

Question 6

Name 5 classes of chemotherapy drugs, briefly describing their mode of action and giving examples

Answer 6

Alkylating agents - bind DNA , Cyclophophamide
Platinum-based drugs - binds DNA Cisplatin
Antimetabolites - inhibit DNA syntehsis methotrexate
Topoisomerase-interactive drugs - inhibit topisomerases doxorubicin
Antimicrotubule drugs - bind microubules, paclitaxel

Question 7

Rate of chemotherapy killing

Answer 7

Each dose kills a constant proportion of tumour cells, repeated doses required, continued after clinical disappearance of disease

Question 8

Combined chemotherapy

Answer 8

more effective than single agents

-needs to have differing mechanisms of action, different side effect profiles, some activity as a single agent

Question 9

Adverse effects of cancer chemotherapy

Answer 9

Common
Most related to main pharmacological action
Determine the dose and dosing interval of chemotherapy
May be annoying, dangerous, and limit compliance of patients with therapy
-Most are reversible or clinically manageable e.g nausea or vomiting

sex steroid deficiency - increased libido, flushing
Mutagenesis - second cancers, teratogenicity

Question 10

best ways to treat each cancer

Answer 10

Chemotherapy - high cure rates in acute lympoblastic leukaemia
Surgery
with radiotherapy
palliation - improve symptoms, survival time e.g lung cancer