[Evaluation of quality of life in oncology]

Studies of quality of life are more and more becoming an integral part of cancer care in situations when treatment of cancer patients is burdened with significant toxicity, and results of survival of these patients are unsatisfactory. Modern concept of health-related quality of life measurement means consensus about its two basic features: multidimensionality of concept, and essentially subjective experience in a treated person. As a minimum, domains of physical, psychological and social are assessed, and the patient is considered to be the primary source of information. The most widely used instruments for quality of life assessment are questionnaires, especially developed for cancer patients, with supplemental items for particular diagnosis. These instruments must satisfy the basic psychometric properties-validity and reliability. Quality of life studies are focused mostly on phase III trials, where differences between treatment arms for tumour response and survival are expected to be small. Another approach is developed in parallel which, based upon quality of life measurement, initiates decisions for the treatment of a set of patients up to health policy level. In these "cost-utility" studies, efficacy and cost of the treatment, and improvement of patients' quality of life are independently estimated, and then integrated in medical decision making.