The Prognostic Impact Of Delayed Time From Biopsy In Men With Low Risk Prostate Cancer Treated With Definitive Sbrt

Active Surveillance (AS) and Stereotactic Body Radiation Therapy (SBRT) are validated treatment approaches for men with low risk prostate cancer. Diagnostic MRI imaging has become widely utilized and at times is used in place of subsequent biopsy. For men undergoing prostate SBRT upfront or after a course of AS, the optimal timing of treatment from last biopsy and its prognostic impact remain elusive. This study attempts to clarify the optimal scheduling of prostate SBRT from the time of biopsy in men with a diagnosis of low risk disease. A total of 684 patients with NCCN low risk prostate cancer were treated with robotic, non-coplanar SBRT at an academic institution from April 10, 2006 to November 18, 2019. The mean age was 65.6 years (41-89). The average pre-treatment PSA was 5.59ng/ml (0.3-9.9). 57 (7.9%) patients were formally placed on Active Surveillance prior to treatment. 78.8% of patients were treated with a dose of 3500cGy (3500-3625) over 5 fractions. 5.6% of patients were treated with ADT. The mean follow-up period was 39.8 months (9-166). Disease Free Survival (DFS) was scored using the Phoenix definition. Cross tabulations were tested by Pearson chi-square analysis. Survival curves were calculated by the Kaplan-Meier method and multivariate analysis was assessed by the log rank test using Cox regression. 88 (12.9%) patients were treated over 12 months (range 1-58) from the time of their biopsy. These patients were more likely to have been on Active Surveillance (29.1% vs. 5.1%, p12 months from biopsy. This might suggest an occult progression prior to treatment. This study provides guidance regarding the prognostic impact of a delay in treatment from last biopsy in patients receiving prostate SBRT.