This study aimed to compare long-term urinary, bowel, and sexual function outcomes in men treated for localized prostate cancer with radical prostatectomy or external-beam radiation therapy. The Prostate Cancer Outcomes Study (PCOS) enrolled 3533 men diagnosed with prostate cancer in 1994 or 1995, and the current analysis focused on 1655 men aged 55 to 74 years who underwent either surgery (1164 men) or radiotherapy (491 men). Functional status was assessed at baseline and at 2, 5, and 15 years post-diagnosis. Using multivariable propensity scoring, the study compared functional outcomes between treatment groups. Key findings include: - At 2 and 5 years, patients undergoing prostatectomy were more likely to experience urinary incontinence and erectile dysfunction compared to those undergoing radiotherapy. - However, by 15 years, no significant differences in the odds of urinary incontinence or erectile dysfunction were observed between the two groups. - Patients undergoing prostatectomy were less likely to have bowel urgency at 2 and 5 years, but this difference was not significant at 15 years. - Despite absolute differences in functional outcomes at 15 years, no significant relative differences were noted between the two groups. The study concluded that at 15 years, there were no significant differences in disease-specific functional outcomes between men treated with prostatectomy or radiotherapy. However, men treated for localized prostate cancer commonly experienced declines in all functional domains over the 15-year follow-up period. These findings are important for counseling men considering treatment options for localized prostate cancer.This study aimed to compare long-term urinary, bowel, and sexual function outcomes in men treated for localized prostate cancer with radical prostatectomy or external-beam radiation therapy. The Prostate Cancer Outcomes Study (PCOS) enrolled 3533 men diagnosed with prostate cancer in 1994 or 1995, and the current analysis focused on 1655 men aged 55 to 74 years who underwent either surgery (1164 men) or radiotherapy (491 men). Functional status was assessed at baseline and at 2, 5, and 15 years post-diagnosis. Using multivariable propensity scoring, the study compared functional outcomes between treatment groups. Key findings include: - At 2 and 5 years, patients undergoing prostatectomy were more likely to experience urinary incontinence and erectile dysfunction compared to those undergoing radiotherapy. - However, by 15 years, no significant differences in the odds of urinary incontinence or erectile dysfunction were observed between the two groups. - Patients undergoing prostatectomy were less likely to have bowel urgency at 2 and 5 years, but this difference was not significant at 15 years. - Despite absolute differences in functional outcomes at 15 years, no significant relative differences were noted between the two groups. The study concluded that at 15 years, there were no significant differences in disease-specific functional outcomes between men treated with prostatectomy or radiotherapy. However, men treated for localized prostate cancer commonly experienced declines in all functional domains over the 15-year follow-up period. These findings are important for counseling men considering treatment options for localized prostate cancer.