Quality of Life in Japanese Men Treated with Intensity Modulated Radiotherapy for Localized Prostate Cancer: Three-Year Longitudinal Evaluation Using Patient-Reported Outcomes of the Expanded Prostate Index Composite (EPIC)

<b>Background/Objectives:</b> We assessed the changes in the quality of life (QOL) of patients with localized prostate cancer who were treated with IMRT, either with or without Androgen Deprivation Therapy (ADT), using the Expanded Prostate Index Composite (EPIC). <b>Methods:</b> Changes in EPIC summary and subdomain scores were evaluated using longitudinal analyses at eight time points up to three years after IMRT. <b>Results:</b> The urinary score and four subdomain scores decreased significantly four weeks after the start of IMRT but returned to the baseline level three months after IMRT. This pattern of change remained consistent, regardless of whether ADT was administered or not. The longitudinal changes in bowel score were the same as those in the urinary score. The recovery of the bowel bother subdomain score was rapid, occurring as early as one month after IMRT. Regardless of whether ADT was administered, there was no difference in longitudinal changes in bowel scores. The sexual score remained consistently low throughout the survey period, ranging from 33 to 35. The baseline score for the sexual bother subdomain was 94.44, but the score for the sexual function subdomain was extremely low at 8.24. The hormonal score at the start of IMRT was 87.37 but increased significantly at two and three years after IMRT. The hormonal bother subdomain score decreased significantly six months after IMRT initiation but subsequently increased, becoming significantly higher three years after IMRT. <b>Conclusions:</b> IMRT has made it possible to minimize deterioration in the quality of life of patients with localized prostate cancer by reducing adverse events.