Abstract
PURPOSE: To compare patient-reported disease-specific functional outcomes after external beam radiation therapy (EBRT) and EBRT combined with low-dose-rate brachytherapy prostate boost (EB-LDR) among men with localized prostate cancer. METHODS AND MATERIALS: The prospective, population-based Comparative Effectiveness Analysis of Surgery and Radiation study enrolled men with localized prostate cancer in 2011 to 2012. The 26-item Expanded Prostate Cancer Index Composite measured patient-reported disease-specific function at baseline and at 6, 12, and 36 months. Higher domain scores indicate better function. Minimal clinically important difference was defined as 6 for urinary incontinence, 5 for urinary irritative function, 4 for bowel function, 12 for sexual function, and 4 for hormonal function. Multivariable linear and logistic regression models were fit to estimate the effect of treatment on patient-reported outcomes. RESULTS: Five-hundred seventy-eight men received EBRT and 109 received EB-LDR. Median patient age was 69 years, and 70% had intermediate- or high-risk disease. Men in the EB-LDR group were younger (P < .001) and less likely to receive androgen deprivation therapy (P < .001). Baseline urinary, bowel, sexual, and hormonal function was similar between treatment groups (P > .05). On multivariable analyses, men receiving EB-LDR reported worse urinary irritative function at 6 months (adjusted mean difference [AMD] -14.4, P < .001), 12 months (AMD -12.9, P < .001), and 36 months (AMD -4.7, P = .034) than men receiving EBRT. At 12 months, men receiving EB-LDR reported worse bowel function (AMD -5.8, P = .002), but these differences were not seen at 36 months. There were no significant differences in sexual or hormone function between treatment groups. CONCLUSIONS: Men treated with EB-LDR report worse bowel function at 1 year and worse urinary irritative function through 3 years compared with men treated with EBRT alone. These side effect profiles should be discussed with patients when considering EB-LDR versus EBRT treatment.