Health-related quality of life in Japanese patients with prostate cancer following proton beam therapy: an institutional cohort study

OBJECTIVE: Many treatment options have guaranteed long-term survival in patients with localized prostate cancer and health-related quality of life has become a greater concern for those patients. The purpose of this study was to reveal the health-related quality of life after proton beam therapy and to clarify the differences from other treatment modalities for prostate cancer. METHODS: Between January 2011 and April 2016, 583 patients were enrolled in the study and health-related quality of life outcomes using the Expanded Prostate Cancer Index Composite questionnaire were evaluated and compared with previous research targeted at Japanese patients. RESULTS: We found a significant decrease in the least square mean scores for urinary and bowel domains excluding the incontinence subscale after proton beam therapy (P < 0.0001) and recovery at a year following treatment. The scores for sexual function in patients without androgen deprivation therapy decreased each year after proton beam therapy (P < 0.0001). The scores for hormones in patients without androgen deprivation therapy remained high and those of patients with androgen deprivation therapy were lower before treatment but were comparable to those of non-androgen deprivation therapy patients at 2 years post-treatment. We found that the impact of radiotherapy including proton beam therapy on urinary condition and sexual function was lower than that of surgery. CONCLUSIONS: For the first time in Japan, we investigated health-related quality of life using Expanded Prostate Cancer Index Composite questionnaires in patients with prostate cancer after proton beam therapy and compared it with other treatment modalities.