Presentation Authors: Adam Kinnaird*, Ryan McLarty, Alexandra Bain, Ambikaipakan Senthilselvan, Gerald Todd, Michael Chetner, Edmonton, Canada
Introduction: Primary whole gland cryotherapy has been shown to be an effective treatment for clinically localized prostate cancer with multiple RCTs demonstrating similar rates of biochemical recurrence (BCR) compared to radiation therapy. While several studies have assessed risk factors of BCR after radical prostatectomy this data is limited for patients undergoing primary whole gland cryotherapy. We therefore sought to determine specific disease, perioperative and early postoperative variables that modify risk of BCR.
Methods: We performed a retrospective analysis of patients who received primary whole gland cryotherapy between 2007 and 2017 at a large tertiary referral center. The primary outcome was BCR, defined as per the Phoenix criteria (PSA nadir + 2.0 ng/ml). Cox proportional hazard regression analysis was used to test models of variables predicting BCR. The Akaike information criteria (AIC) method was used to model the optimal PSA nadir cut-off for risk of BCR.
Results: 350 of 391 patients who received cryotherapy during the study period at our institution were identified as having received primary whole gland cryotherapy. Median follow up time was 38.6 months. BCR occurred in 119 (34%) patients. Age (HR=1.05, pâ‰¤0.01) and NCCN risk categories (Intermediate risk: HR=6.11, p=0.07; High risk: HR=12.3, p=0.01; Very high risk: HR=14.9, p=0.01) were found to be independently associated with increased risk of BCR. A PSA nadir â‰¤0.7 was determined to best predict BCR with PSA 0.7 increasing risk of BCR by a HR=4.36 (pâ‰¤0.01).
Conclusions: We have identified several robust disease specific and early postoperative predictors of BCR. These risk factors may be used in counselling patients before their cryoablation as well as for potentially selecting patients who may require closer follow-up based on PSA nadir ï‚³0.7 or higher risk features.