Association of salvage cryoablation with decreased utilization of androgen deprivation therapy for recurrent prostate cancer after radiotherapy.

Abstract

358 Background: Cryoablation is an established treatment for recurrent prostate cancer after primary radiotherapy, but outcomes data are mostly limited to uncontrolled case series. We assessed salvage cryoablation efficacy with a comparative analysis in a large national cohort. Methods: Patients with clinically localized prostate cancer treated with primary radiotherapy from 2000 to 2015 were identified in the Veterans Affairs Informatics and Computing Infrastructure (VINCI) dataset. Prostate-specific antigen (PSA) recurrence was defined as nadir + 2 ng/mL. Inclusion criteria included availability of serial PSA measures for ≥ 3 years after completion of radiotherapy and PSA < 10 ng/mL at recurrence. Salvage cryotherapy was identified with procedure- and fee-based billing codes. Chi square and Wilcoxon analysis was utilized for descriptive statistics; and Kaplan Meier analyses for time to androgen deprivation therapy (ADT). Results: Among 35,502 patients who underwent primary radiotherapy, 4,391 (12.3%) developed biochemical recurrence a median (IQR) of 4.5 (2.7, 6.9) years after treatment. Of these, 3889 (88.9%) had PSA < 10 ng/mL at time of recurrence, of whom 95 (2.4%) underwent salvage cryoablation. Cryoablation patients were younger at initial diagnosis (60 years versus 65 years, p < 0.01); had a lower pre-treatment PSA (6.6 ng/mL versus 7.8 ng/mL, p < 0.01); and had a lower PSA nadir (0.04 ng/mL versus 0.19 ng/mL, p<0.01). There were no between-group differences for clinical stage at initial diagnosis (p = 0.22) or African American prevalence (34.7% versus 29%, p =0.27). After recurrence, median (IQR) follow-up for those who did and did not receive cryoablation was 9.1 (7.2, 9.11) and 8.1 (5.4, 10.9) years, respectively. Cryoablation patients were less likely to receive ADT (40% versus 55%, p < 0.01); and, among those who did, time to ADT from recurrence was significantly longer compared to those who did not receive cryoablation (15.5 months versus 5.8 months, p<0.01). Conclusions: Salvage cryoablation is associated with decreased utilization of ADT in patients with biochemical recurrence after radiation.