External beam radiation therapy with or without low-dose-rate brachytherapy: Analysis of favorable and unfavorable intermediate-risk prostate cancer patients.

To compare the tumor control and toxicity in men with intermediate-risk prostate cancer treated with either external beam radiation therapy (EBRT) or EBRT plus low-dose-rate brachytherapy (combo-RT).

Between 1995 and 2012, 579 men with intermediate-risk prostate cancer were treated with either EBRT (n = 388) or combo-RT (n = 191). Outcomes assessed included biochemical recurrence-free survival (bRFS), distant metastasis-free survival (DMFS), and cumulative incidence of genitourinary (GU) and gastrointestinal toxicity. Favorable and unfavorable intermediate-risk subgroups were analyzed.

Median followup was 7.5 years. Combo-RT group had improved 10-year bRFS compared with EBRT (91.7% vs. 75.4%, p = 0.014). On multivariable analysis, combo-RT (hazard ratio, 0.48; 95% confidence interval: 0.25, 0.92; p = 0.03) was associated with improved bRFS. Combo-RT had significantly improved bRFS compared with EBRT in the unfavorable subgroup (p = 0.02) but not in the favorable subgroup (p = 0.37). DMFS was similar within the entire cohort and by risk group. Combo-RT was associated with an increased rate in the 6-year cumulative incidence of Grade 3 GU toxicity (hazard ratio, 3.48; 95% confidence interval: 1.1, 11.1; p = 0.026); however, 57% of Grade 3 GU toxicity was resolved, 29% had partial improvement, and only 1 patient had persistent Grade 3 GU toxicity.

In intermediate-risk prostate cancer, combo-RT improved bRFS but not DMFS and increased Grade 3 GU toxicity. The bRFS benefit was limited to unfavorable intermediate-risk patients.

Brachytherapy. 2017 May 09 [Epub ahead of print]

Ahmed E Abugharib, Robert T Dess, Payal D Soni, Vrinda Narayana, Cheryl Evans, Mohamed S Gaber, Felix Y Feng, Patrick W McLaughlin, Daniel E Spratt

Department of Radiation Oncology, University of Michigan, Ann Arbor, MI; Department of Clinical Oncology, Sohag University Hospital, Sohag, Egypt., Department of Radiation Oncology, University of Michigan, Ann Arbor, MI., Department of Radiation Oncology, University of Michigan, Ann Arbor, MI; Department of Radiation Oncology, Providence Hospital, Novi, MI., Department of Clinical Oncology, Sohag University Hospital, Sohag, Egypt., Department of Radiation Oncology, University of California San Francisco, San Francisco, CA., Department of Radiation Oncology, University of Michigan, Ann Arbor, MI. Electronic address: .