Association between pelvic nodal radiotherapy and patient-reported functional outcomes through 5 years among men undergoing external-beam radiotherapy for prostate cancer: An assessment of the comparative effectiveness analysis of surgery and radiation (CEASAR) cohort.

BACKGROUND: The role of pelvic irradiation in men receiving external beam radiotherapy (EBRT) for prostate cancer is unclear, in part due to a lack of data on patient-reported outcomes. We sought to compare functional outcomes for men receiving prostate and pelvic versus prostate-only radiotherapy, longitudinally over 5 years. MATERIALS AND METHODS: We performed a population-based, prospective cohort study of men with clinically-localized prostate cancer undergoing EBRT. We examined the effect of prostate and pelvic (n = 102) versus prostate-only (n = 485) radiotherapy on patient-reported disease-specific (using the Expanded Prostate Cancer Index Composite[EPIC]-26) and general health-related (using the SF-36) function, over 5 years. Regression models were adjusted for outcome-specific baseline function, clinicopathologic characteristics, and androgen deprivation therapy (ADT). RESULTS: 587 men (median [quartiles] age 69 [64-73] years) met inclusion criteria and completed ≥1 post-treatment survey. More men treated with prostate and pelvic radiotherapy had high-risk disease (58% vs. 18%, P < 0.01) and received ADT (75% vs. 41%, P < 0.01). These men reported worse sexual (6 months-5 years), hormonal (at 6 months), and physical (6 months-5 years) function. Accounting for baseline function, patient and tumor characteristics, and use of ADT, pelvic irradiation was not associated with statistically or clinically significant differences in bowel function, urinary incontinence, irritative voiding symptoms or sexual function through 5-years (all P > 0.05). Marginally clinically important differences were noted in hormonal function at 3-years (adjusted mean difference 4.7, 95% confidence interval [1.2-8.3]; minimally clinically important difference (MCID) 4 to 6) and 5-years (4.2, [0.4-8.0]) following treatment. After adjustment, there was a transient statistically significant, but not clinically important, difference in emotional well-being at 6 months (3.0, [0.19-5.8]; MCID 6) that resolved by 1 year and no differences in physical functioning or energy and fatigue. CONCLUSION: This prospective, population-based cohort study of men with localized prostate cancer treated with EBRT, showed no clinically important differences in disease-specific or general health-related quality of life with the addition of pelvic irradiation to prostate radiotherapy, supporting the use of pelvic radiotherapy when it may be of clinical benefit, such as men with increased risk of nodal involvement.