Comparison of AUA and phoenix definitions of biochemical failure following permanent brachytherapy for prostate cancer

Abstract

To compare biochemical recurrence free survival (BCRFS) and cancer-specific survival (CSS) after brachytherapy using the AUA and the Phoenix definitions. 2634 men with T1-T4N0M0 prostate cancer were treated with brachytherapy with or without neoadjuvant hormonal therapy or external beam radiation therapy. Five, 10, and 15- year BCRFS and CSS were estimated with Kaplan-Meier estimates with log rank. Multivariate analysis of survival was performed with Cox regression analysis. Median age was 66, follow-up was 8.6 years, and prostate specific antigen was 6.9. Overall, 11.1% (n = 293) of patients experienced Phoenix BCR and 17.48% (n = 457) experienced AUA BCR. The rates of AUA BCR and Phoenix BCR were significantly different at 5 and 10-years but not at 15 years. Patients treated with BED ≤ 200 Gy were more likely to experience AUA BCR (22.5% vs. 12.4%, OR 1.44, p < 0.001) and Phoenix BCR (14.3% and 8.3%, OR 1.37, p < 0.001) than patients treated with a BED > 200 Gy. Compared to the Phoenix definition, the AUA definition of BCR after brachytherapy is associated with significantly worse BCRFS for the first 15 years after treatment. Receiving a BED > 200, which cannot be achieved without the addition of brachytherapy, is associated with better BCRFS and CSS. Our findings reaffirm the importance of dose in the management of prostate cancer.