Treatment results of brachytherapy vs. external beam radiation therapy for intermediate-risk prostate cancer with 10-year followup

Abstract

PurposeTo compare 10-year treatment outcomes of brachytherapy vs. external beam radiation therapy for patients with intermediate-risk prostate cancer (IRPC). Methods and MaterialsBetween 2004 and 2007, 93 IRPC patients underwent brachytherapy using iodine-125 to a dose of 145 Gy without supplemental external radiation. A retrospective comparison was performed to a contemporary cohort of 597 patients treated with external beam radiation therapy to a median dose of 75.3 Gy using a propensity score-matched analysis. ResultsMedian followup was 7.8 years. With brachytherapy, 51.6% had Gleason score 7 vs. 72.0% for external radiation (p < 0.001). Median initial prostate-specific antigen was 8.3 for brachytherapy vs. 9.4 for external radiation (p = 0.01). Neoadjuvant androgen deprivation therapy was given in 59.5% of external radiation vs. 10.8% of brachytherapy patients (p < 0.001). The 10-year freedom from biochemical failure (FFBF) for brachytherapy was 81.7% vs. 54.5% for external radiation (p = 0.002). Unfavorable intermediate-risk patients experienced borderline significant improved FFBF with brachytherapy (p = 0.08). The 10-year freedom from salvage therapy for brachytherapy was 93.2% vs. 72.2% for external radiation (p = 0.006). There were no significant differences in distant metastases-free survival, prostate cancer-specific survival, or overall survival after adjusting for age. Multivariate analysis with propensity score matching showed that brachytherapy remained an independent predictor for improved FFBF (p = 0.007). Grade 1 and 2 late rectal complication rate was 6.5% for brachytherapy vs. 15.2% for external radiation (p = 0.02). ConclusionsBrachytherapy using iodine-125 without supplemental external radiation is a reasonable treatment option for selected IRPC patients.