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

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 35.8 cc, and pretreatment prostate-specific antigen of 5.6 ng/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 145.9 Gy, 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–<25 cc 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–<25 cc 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 25 cc was an independent predictor of BCF.