Strength of Endpoints
Commonly measured endpoints for adult and pediatric cancer treatment studies are listed below in descending order of strength:
- Total mortality (or overall survival from a defined time).
This outcome is arguably the most important one to patients and is also the most easily defined and least subject to investigator bias.
- Cause-specific mortality (or cause-specific mortality from a defined time).
Although this may be of the most biologic importance in a disease-specific intervention, it is a more subjective endpoint than total mortality and more subject to investigator bias in its determination. This endpoint may also miss important effects of therapy that may actually shorten overall survival.
- Carefully assessed quality of life.
This is an extremely important endpoint to patients. Careful documentation of this endpoint within a strong study design is therefore sufficient for most physicians to incorporate a treatment into their practices.
- Indirect surrogates.
- Event-free survival.
- Disease-free survival.
- Progression-free survival.
- Tumor response rate.
These endpoints may be subject to investigator interpretation. More importantly, they may, but do not automatically, translate into direct patient benefit such as survival or quality of life. Nevertheless, it is rational in many circumstances to use a treatment that improves these surrogate endpoints while awaiting a more definitive endpoint to support its use.