Turkish validation of the expanded prostate cancer index composite in prostate cancer patients

Prostate cancer is the most common cancer in men, and long life spans are expected, especially in localized diseases. Treatment-related side effects may occur in the post-treatment period, which may affect the patient's quality of life (QOL). The Expanded Prostate Cancer Index Composite (EPIC) is a symptom scale developed in 2000 that measures QoL in prostate cancer patients. This scale, translated into many different languages and validated, is frequently used in daily practice globally. This thesis aims to translate the EPIC scale into Turkish and then provide Turkish validation by making validity and reliability analyses of the scale. The translated Turkish EPIC was administered to the patients five times with the EORTC-QLQ C30 and PR25 scales. The study included one hundred five patients diagnosed with prostate cancer and undergoing definitive or postoperative RT in our department. In the reliability analysis of the scale, Cronbach's alpha values of the whole scale were measured between 0.866, and Cronbach's alpha values of the main scales were measured between 0.654 and 0.969. It was revealed that the internal consistency of the scale was excellent. In the test-retest analysis, the correlation values of the main scales were measured between 0.413 and 0.861, and the reproducibility of the scale was proven. The pilot study with 20 patients was successfully completed, thus providing face validity. Sensitivity to change analysis, the correlation between scales, criterion validity, and explanatory factor analyses were performed, and results proving the scale's validity were obtained in all analyses. As a result, the validity and reliability of the Turkish EPIC scale have been proven, and the scale has been validated in Turkish.