Background: In cancer clinical trials, the standard end points include response rates, progression free and overall survival, toxicity. These evaluation criteria do not measure how the cancer and its treatment affect the quality of life of cancer patients.
Design: The relevant literature was reviewed for the purposes of determining when, how and why quality of life should be measured in cancer clinical trials. The resulting clinical benefits were also reviewed.
Results: Along with survival, quality of life is the main end point of comparative clinical trials. Its evaluation can provide physicians and patients with important information and help to identify a better treatment. Cancer-specific questionnaires with forms for specific tumour types sites have been developed and have proven to be more sensitive to changes than generic questionnaires. Quality-of-life evaluation before the start of treatment may be an important prognostic factor, even independent from performance status. Clinical benefit assessment presents important shortcomings and the clinical relevance of this evaluation should be interpreted with caution.
Conclusions: Quality of life is a fundamental task of oncological research. More studies are necessary to overcome the difficulties in assessing and interpreting this concept and the clinical benefits based on it.