MP73-18: Intermediate-term Oncologic and Functional Outcomes after Salvage Cryoablation for Localized, Biopsy-Proven Recurrent Prostate Cancer Following Primary External Beam Radiotherapy versus Primary Cryotherapy.
Introduction: Local prostate cancer recurrence following treatment with external beam radiation (XRT) or cryotherapy may be treated with salvage cryotherapy (SCT), but little is known about how the primary treatment modality influences SCT outcomes. We compare the oncologic and functional outcomes of patients who received whole- or partial-gland SCT after primary XRT (XRT-SCT) or primary cryoablation (CRYO-SCT). Methods: The Duke Prostate Cancer database and the Cryo On-Line Data (COLD) registry were used to analyze data on XRT-SCT and CRYO-SCT patients. Propensity score matching was performed with variables selected that had an impact on oncologic outcomes. The primary outcome was biochemical progression-free survival (BPFS), as defined by the Phoenix criteria. Urinary incontinence, rectourethral fistula formation, and erectile dysfunction were secondary outcomes. The Kaplan-Meier log-rank test, as well as Cox proportional hazards modelling, were used to compare BPFS rates and identify factors influencing BPFS. To identify factors that can predict biochemical recurrence (BCR), a multivariate logistic regression analysis was performed. Results: 419 XRT-SCT and 63 CRYO-SCT patients met the inclusion criteria, which was reduced to 63 patients in each cohort after propensity matching. On the 2- and 5-year Kaplan-Meier log-rank tests, no difference in BPFS was found. In multivariate analysis, the CRYO-SCT group had similar rates of BCR as compared to XRT-SCT (OR=1.63; p= 0.2). For both groups, higher (OR = 36.38; p=0.03) and intermediate (OR 8.26; p= 0.01) D’Amico risk category was associated with higher rates of BCR relative to low-risk. There were no significant differences in post-salvage changes to functional outcomes. Conclusions: Oncologic and functional outcomes following salvage cryoablation appear to be similar for well-matched patients who underwent XRT-SCT or CRYO-SCT. Risk category was an important predictor of oncologic outcomes, suggesting the importance of close follow-up after primary treatment to promote early salvage treatment. SOURCE OF Funding: None
