Comparative Effectiveness Research in Localized Prostate Cancer: A 10-Year Follow-up Cohort Study

Abstract

Long-term comparative effectiveness research on localized prostate cancer treatments is scarce, and evidence is lacking especially for brachytherapy. The aim of this study was to assess the long-term impact of the side effects of radical prostatectomy, brachytherapy, and external radiation therapy on patients with localized prostate cancer at 10 years, using propensity score analyses. This was a prospective observational study of a cohort of men who received a diagnosis of clinically localized prostate cancer (clinical stage T1 or T2, low and intermediate risk group) and were treated with radical prostatectomy (n = 139), brachytherapy (n = 317), or external radiation therapy (n = 194). Treatment decisions were jointly made by patients and physicians. Patient-reported outcome (PRO) evaluation included the Expanded Prostate Cancer Index Composite and Short Form-36, administered centrally by telephone interviews before and annually after treatment. The Expanded Prostate Cancer Index Composite covers urinary, bowel, sexual, and hormonal domains. To assess PRO changes over time, while accounting for correlation among repeated measures, generalized estimating equation models adjusted by propensity scores were constructed. The PRO completion rate at 10 years was 85.8%. Generalized estimating equation models showed that the pattern of radical prostatectomy side effects, with substantial urinary incontinence and sexual dysfunction, remained until 10 years after treatment (standard deviation [SD], -1.1 and -1.3, respectively). Brachytherapy produced late deterioration in urinary continence (SD, -0.4) and sexual function (SD, -0.9) that appeared midterm, but the differences from radical prostatectomy remained statistically significant at 10 years (P < .001 after adjusting by propensity score). External radiation therapy showed similar results to brachytherapy, but with bowel bother (SD, -0.3). Although late deterioration in radiation therapy groups attenuated differences from radical prostatectomy, relevant PRO differences still remained after 10 years. Our findings support that brachytherapy is the treatment option that causes the least impact on PROs; it is therefore an alternative to be considered when making evidence-based decisions on localized prostate cancer treatment.