Comparative Study Between Salvage Cryoablation of The Prostate After Primary Radiotherapy Failure and After Primary Cryotherapy Failure For Clinically Localized Prostate Cancer

INTRODUCTION AND OBJECTIVE: Salvage cryoablative therapy for biopsy-proven recurrence after primary radiation or ablation treatment failure for clinically localized prostate cancer (PCa) is common. In this observational study, we aim to explore biochemical recurrence-free survival when salvage cryotherapy is performed after primary cryotherapy failure versus primary external beam radiotherapy failure in patients initially presenting with clinically localized prostate cancer. METHODS: After IRB approval, data for patients treated with salvage cryotherapy after primary external beam radiotherapy (group A) or after primary cryotherapy (group B) were collected from The Duke Prostate Cancer database and the Cryo On-Line Data (COLD) registry. Biochemical recurrence (BCR), using Phoenix criteria, after 2 and 5 years were the primary oncological outcomes. Urinary incontinence, erectile dysfunction, fistula and retention were considered as secondary functional outcomes and were assessed 12 months after salvage cryotherapy. We estimated the association between treatment and biochemical progression-free survival (BPFS) using inverse probability weighted (IPTW) Cox proportional hazards regression. Propensity score analysis, adjusting for Gleason, risk, and PSA, was implemented to account for non-random assignment of primary treatment. To test for differences in the secondary functional outcomes between treatment modalities we used Pearson's c test or Fishers exact test, corrected for IPTW. RESULTS: A total of 515 unweighted subjects met inclusion criteria and had complete data for the primary analysis.Those in group B showed an increase in 2-year BCR (HR 1.94; 95% CI, 1.1e1.34) when compared to group A. The same association was seen in 5-year BCR (HR: 1.66; 95% CI,1.01-2.72).There was no statistical difference between the 2 groups regarding the functional outcomes, although incontinence and erectile dysfunction was higher group A than group B. CONCLUSIONS: Risk of biochemical recurrence for salvage cryotherapy after primary cryoablation is higher than following primary external beam radiotherapy. This should be taken in consideration when selecting primary in-situ therapy for PCa. Further work with larger number of patients is needed to assess reasons for failure including whether they are in field or out of field of treatment.