Biochemical and clinical experience with real-time intraoperatively planned permanent prostate brachytherapy

Abstract

PurposeTo evaluate patient characteristics and dosimetric parameters that predict biochemical failure (BCF) after real-time planned low-dose-rate prostate brachytherapy. MethodsFrom 1998 to 2008, a low-risk cohort by National Comprehensive Cancer Network criteria of 341 men with a median followup of 41.6 months was analyzed. This cohort had a median age of 65.1 years, prostate volume of 35.8cc, and pretreatment prostate-specific antigen of 5.6ng/mL. Patients had predominately Gleason 6 (95.9%) and T1c (81.3%) disease. About 3.6% of the patients received androgen deprivation therapy. Kaplan–Meier and Cox proportional hazards survival analysis methods were used to analyze predictors of BCF (Phoenix definition). ResultsAt 72 months, freedom from BCF was 91.1% (95% confidence interval=85.0–94.8). The median D90 was 145.9Gy, and the median V100 was 90.3%. Because of infrequent BCF, the following prostate volume groups were examined: 15–<25, 25–<35, 35–<45, and 45+cc. Of all possible predictors, only small prostate volume (15–<25cc group) was significantly associated with BCF (hazard ratio=8.44, 95% confidence interval=1.82–39.14, p=0.007). Using Kaplan–Meier analysis, time to BCF was also significantly increased in the lowest prostate volume 15–<25cc group with 24.1% failing at 48 months compared with 1.6–5.1% among the other groups. ConclusionsReal-time planned low-dose-rate prostate brachytherapy provides excellent biochemical control as a single-agent treatment for low-risk prostate cancer with 91.1% freedom from BCF at 72 months. Only prostate volume less than 25cc was an independent predictor of BCF.