How Do You Know that a Treatment Works?

Question 1

List and define the classifications of tumour response to treatment.

Answer 1

1 - Complete response - disappearance of all signs of disease.

2 - Partial response - a reduction in tumour volume by at least 30%.

3 - Stable disease - no significant change.

4 - Disease progression - an increase in tumour volume by at least 20%, or the presence of new metastases.

*A positive tumour response doesn’t necessarily mean prolonged survival.

Question 2

Define overall survival time.

Define disease-free survival time.

Define progression-free survival time.

Answer 2

• Overall survival time is the time from the start of the treatment to death.
• Disease-free survival time is the time between a radical treatment removing a disease and the point at which the disease relapses (if ever).
• Progression-free survival time is the time prior to disease progression.

Question 3

What is a hazard ratio?

Answer 3

• A hazard ratio is a measure of relative difference in survival time between a new and a standard treatment.
• Hazard ratio = risk of death in the new treatment / risk of death in the standard treatment.

Question 4

What is the function of the ALK gene?

Give an example of a cancer associated with the ALK gene.

Answer 4

• The ALK gene codes for a membrane-associated tyrosine kinase receptor of the insulin receptor superfamily.
• Mutations in the ALK gene are associated with non-small cell lung cancer (among others).

Question 5

List the phases of clinical trials.

What are the aims of these phases?

Answer 5

• Phase 1: to find a safe dose of a new treatment and understand the toxicities.
• Phase 2: to determine if the new treatment has sufficient efficacy to be worthy of further investigation.
• Phase 3: to provide sufficient evidence to potentially change clinical practice (with an RCT!).