Background: The aim of this study was to describe changes in patient-reported functional outcome measures (PROMs) comparing pre-treatment and 12 months after radical prostatectomy (RP), external beam radiation therapy (EBRT), brachytherapy and active surveillance (AS). Methods: Men enrolled from 2010 to 2019 in the South Australian Prostate Cancer Clinical Outcomes Collaborative registry a prospective clinical registry were studied. Urinary, bowel, and sexual functions were measured using Expanded Prostate Cancer Index Composite (EPIC-26) at baseline and 12 months post-treatment. Higher scores on the EPIC-26 indicate better function. Multivariable regression models were applied to compare differences in function and extent of bother by treatment. Results: Of the 4926 eligible men, 57.0% underwent RP, 20.5% EBRT, 7.0% brachytherapy and 15.5% AS. While baseline urinary and bowel function varied little across treatment groups, sexual function differed greatly (adjusted mean scores: RP = 56.3, EBRT = 45.8, brachytherapy = 61.4, AS = 52.8; p < 0.001). Post-treatment urinary continence and sexual function declined in all treatment groups, with the greatest decline for sexual function after RP (adjusted mean score change − 28.9). After adjustment for baseline differences, post-treatment sexual function scores after EBRT (6.4; 95%CI, 0.9–12.0) and brachytherapy (17.4; 95%CI, 9.4–25.5) were higher than after RP. Likewise, urinary continence after EBRT (13.6; 95%CI, 9.0-18.2), brachytherapy (10.6; 95%CI, 3.9–17.3) and AS (10.6; 95%CI, 5.9–15.3) were higher than after RP. Conversely, EBRT was associated with lower bowel function (− 7.9; 95%CI, − 12.4 to − 3.5) than RP. EBRT and AS were associated with lower odds of sexual bother (OR 0.51; 95%CI, 0.29–0.89 and OR 0.60; 95%CI, 0.38–0.96, respectively), and EBRT with higher odds of bowel bother (OR 2.01; 95%CI, 1.23–3.29) compared with RP. Conclusion: The four common treatment approaches for prostate cancer were associated with different patterns of patient-reported functional outcomes, both pre- and 12 months post-treatment. However, after adjustment, RP was associated with a greater decline in urinary continence and sexual function than other treatments. This study underscores the importance of collecting baseline PROMs to interpret post-treatment functional outcomes.
