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

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

doi:10.1016/j.brachy.2017.04.001

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

Brachytherapy. 2017 Jul-Aug;16(4):782-789. doi: 10.1016/j.brachy.2017.04.001. Epub 2017 May 9.

Authors

Ahmed E Abugharib¹, Robert T Dess², Payal D Soni², Vrinda Narayana³, Cheryl Evans³, Mohamed S Gaber⁴, Felix Y Feng⁵, Patrick W McLaughlin³, Daniel E Spratt⁶

Affiliations

¹ Department of Radiation Oncology, University of Michigan, Ann Arbor, MI; Department of Clinical Oncology, Sohag University Hospital, Sohag, Egypt.
² Department of Radiation Oncology, University of Michigan, Ann Arbor, MI.
³ Department of Radiation Oncology, University of Michigan, Ann Arbor, MI; Department of Radiation Oncology, Providence Hospital, Novi, MI.
⁴ Department of Clinical Oncology, Sohag University Hospital, Sohag, Egypt.
⁵ Department of Radiation Oncology, University of California San Francisco, San Francisco, CA.
⁶ Department of Radiation Oncology, University of Michigan, Ann Arbor, MI. Electronic address: sprattda@med.umich.edu.

PMID: 28499487
DOI: 10.1016/j.brachy.2017.04.001

Abstract

Purpose: 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).

Methods and materials: 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.

Results: 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.

Conclusions: 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.

Keywords: Brachytherapy; Combination therapy; Dose escalation; Intermediate-risk; PSA; Prostate cancer.