The Role of External Beam Radiotherapy With or Without Low Dose Rate Brachytherapy in Treatment of Intermediate Risk Cancer Prostate

Abstract Background: Patients with intermediate risk cancer prostate represent the largest risk group with remarkable clinical and biologic heterogeneity and are further subdivided into favorable intermediate risk (FIR) and unfavorable intermediate risk (UIR) subgroups with higher rates of deaths, biochemical and metastatic recurrences. Aim of Study: To investigate the difference between external beam radiation therapy (EBRT) and EBRT plus low-dose-rate brachytherapy (combo-RT) on tumor control and toxicity profile in patients with intermediate risk cancer prostate. Patients and Methods: A cohort of 579 patients withinter-mediate-risk cancer prostate were treated between 1995 and 2012 by either EBRT (n: 388) or combo-RT (n: 191). The aim of the study was to assess biochemical recurrence free survival (bRFS), distant metastasis free survival (DMFS), and cumu-lative incidence of genitourinary (GU) and gastrointestinal toxicity in the favorable and unfavorable subgroups. Results: At a median follow-up period at 7.5 yr, an im-provement in the 10 yr bRFS was evident in the patients treated with Combo-RT compared to those treated with EBRT alone (91.7% vs. 75.4%, p 5 0.014). Multivariate analysis showed that combo-RT was associated with improved bRFS with improvement of hazard ratio (HR, 0.48; 95% confidence interval: 0.25, 0.92; p 0.03). Such an improvement was statistically significant in unfavorable intermediate risk patients (p 5 0.02), but not in the favorable risk ones (p 5 0.37). For DMFS, no difference was found. An increase in the 6-year cumulative incidence rate of Grade 3 genitourinary toxicity was associatedwith Combo RT (HR, 3.48; 95% confidence interval: 1.1, 11.1; p 0.026). Conclusions: Treatment of intermediate-risk prostate cancer with combo-RT improved bRFS but not DMFS at the expense of increased Grade 3 genito urinary toxicity. Improve-ment in bRFS was found in unfavorable intermediate-risk patientsbut not in the favorable risk patients.