A Pooled Analysis of Biochemical Failure in Intermediate-risk Prostate Cancer Following Definitive Stereotactic Body Radiotherapy (SBRT) or High-Dose-Rate Brachytherapy (HDR-B) Monotherapy.

OBJECTIVES: To investigate biochemical relapse-free survival (BRFS) in men with National Comprehensive Cancer Network-defined intermediate-risk prostate cancer (PC) treated with either stereotactic body radiotherapy (SBRT) or high-dose-rate brachytherapy (HDR-B) monotherapy. MATERIALS AND METHODS: A retrospective, multi-institutional analysis of 437 patients with intermediate-risk PC treated with SBRT (N=300) or HDR-B (N=137) was performed. Men who underwent SBRT were treated to 35 to 40 Gy in 4 to 5 fractions. A total of 95.6% who underwent HDR-B were treated to 42 Gy in 6 fractions. Baseline patient characteristics were compared using a T test for continuous variables and the Mantel-Haenszel χ metric or Fisher exact test for categorical variables. Kaplan-Meier curves were generated to estimate 5-year actuarial BRFS. Multivariate analysis using a Cox proportional-hazards model was used to evaluate factors associated with biochemical failure. RESULTS: The mean age at diagnosis was 68.4 (SD±7.8) years. T-category was T1 in 63.6% and T2 in 36.4%. Mean initial prostate-specific antigen was 7.4 (SD±3.4) ng/mL. Biopsy Gleason score was ≤3+4 in 82.8% and 4+3 in 17.2%. At a median of 4.1 years of follow-up, the BRFS rate (Phoenix definition) was 96.3%, with no difference when stratifying by treatment modality or biologically equivalent dose (BED1.5). On multivariate analysis, age (hazard ratio 1.08, P=0.04) and biopsy Gleason score (hazard ratio 2.48, P=0.03) were significant predictors of BRFS. CONCLUSIONS: With a median follow-up period of 4 years, SBRT and HDR-B monotherapy provide excellent BRFS in intermediate-risk PC. Longer-term follow-up is necessary to determine the ultimate efficacy of these hypofractionated approaches, but they appear promising relative to standard fractionation outcomes.

Prostate Cancer Antigen 3 Score Does Not Predict for Adverse Pathologic Features at Radical Prostatectomy or for Progression-free Survival in Clinically Localized, Intermediate- and High-risk Prostate Cancer.

OBJECTIVE: To evaluate whether preoperative urinary prostate cancer antigen 3 (PCA3) scores predict for adverse pathologic features (APFs) or progression-free survival (PFS) in men with intermediate- or high-risk prostate cancer (PCa) undergoing radical prostatectomy (RP). MATERIALS AND METHODS: One hundred nine men with intermediate- (n = 52) or high-risk (n = 57) PCa who underwent RP were retrospectively identified. Logistic regression analysis was performed to evaluate the association of PCA3 score with various APFs (eg, extracapsular extension, seminal vesicle invasion, etc.). Among 78 men with ≥1 year of follow-up, the association between PCA3 score and PFS was assessed using Cox regression analysis. RESULTS: At RP, 52% of patients had at least 1 APF, and with median follow-up of 2.3 years, overall 3-year PFS was 70%. PCA3 was not a significant predictor of any APF on multivariate analysis (MVA), whereas canonical predictors (eg, biopsy Gleason score and initial prostate-specific antigen) remained predictive of various APFs. No significant predictors for PFS were found on MVA, although certain canonical predictors (eg, National Comprehensive Cancer Network risk group) were significant predictors of PFS on univariate analysis (UVA). PCA3 score was not a significant predictor of PFS on either UVA or MVA. CONCLUSION: Unlike in lower risk cohorts, increasing PCA3 score was not associated with any APF in this higher risk cohort, despite enrichment for APFs, nor was it associated with PFS. Notably, multiple known preoperative predictors for APFs were significant on MVA, and multiple predictors were associated with PFS on UVA. Therefore, PCA3 may not be a useful adjunct predictive marker in men with intermediate- or high-risk PCa.