Measurement of quality of life in localized prostatic cancer patients treated with radiotherapy. Development of a prostate cancer-specific module supplementing the EORTC QLQ-C30

The purpose of this study was to construct a multidimensional self-administered quality of life questionnaire specific to prostate cancer within the EORTC framework and to test its applicability, clinical relevance and psychometry. A proposed prostate cancer-specific module and the standardized EORTC QLQ-C30 version 1.0 were tested in 192 post-irradiated patients. Psychometric analyses comprised item convergent and discriminant validity for scaling success, analysis of the internal consistency of the multi-item scales and the validity of the scales. The clinical relevance was explored by correlation analysis including disease and treatment related parameters. The minimum psychometric criteria were met. The measurements revealed problem areas in sexuality with a mean score of 54 (SD=33) on a 0-100 scale, and in bowel functioning, scoring 25 on average (SD=17). Urinary complaints only reached a mean score of 6 (SD=19). Compared to earlier measurements on untreated or irradiated localized cancer patients using the same core questionnaire, the physical and psychological scales showed higher values and the symptom scales lower symptom burden. The constructed questionnaire seems applicable and clinically relevant. The psychometric analysis revealed a few items to be revised. Patients with localized prostatic carcinoma treated with radiotherapy have a high quality of life compared to patients with localized cancer of other origin.