[Quality of life measurement in breast cancer patients]

Malignant tumors are among the leading causes of death and long-term health impairment worldwide, and their incidence is steadily rising due to demographic and lifestyle changes. Breast cancer is the most common malignant tumor in women. Although screening, modern immune, targeted, monoclonal anti-HER2 and endocrine therapies, and oncoplastic surgery have significantly improved survival, more and more patients are living with long-term side effects and psychosocial burdens. Due to this, the success of oncological care cannot be measured solely by classic endpoints such as overall survival, disease-free survival, and/or progression-free survival. Health-related quality of life (HRQoL) is a multidimensional construct that takes into account physical symptoms, psychological state, social and role functions, and functional autonomy, which in breast cancer is further supplemented by body image, sexual function, and female identity. HRQoL measurement relies on validated tools, such as the EORTC-QLQ-C30 questionnaire and its breast cancer-specific module (EORTC-QLQ-BR23), as well as the FACT questionnaires (FACT-G and FACT-B). Several large-sample meta-analyses based on individual patient data have confirmed that baseline HRQoL scores are prognostic markers of patient survival, even after adjusting for tumor stage and other clinicopathological factors. However, several factors complicate the clinical interpretation of HRQoL: the subjective nature of the measurement(s), response bias, cognitive and physical limitations associated with disease progression, the phenomenon of response shift, and the heterogeneous definition of minimally clinically significant differences. In addition, patients' educational level and health literacy may also influence the reliability of questionnaire completion. The aim of this review is to systematize the conceptual, methodological, and clinical aspects of measuring the quality of life of cancer patients, especially in breast cancer, to present the most commonly used measurement tools, and to highlight why HRQoL can now be considered not only a patient-centered outcome, but also one with prognostic and health policy significance. Orv Hetil. 2026; 167(14): 530-538.