Purpose: We assessed the efficacy of cryoablation of the prostate with an emphasis on finding predictive factors that lead to improved outcome.
Materials and methods: A total of 187 patients with locally recurrent prostate cancer after radiotherapy underwent salvage cryoablation of the prostate, and were studied after a mean followup of 39 months. Survival analysis was performed with the Kaplan-Meier method. Several variables were tested for predictive value using the Cox regression model including serum prostate specific antigen before radiotherapy, serum prostate specific antigen at cryoablation, clinical stage before radiotherapy, Gleason score before radiotherapy, Gleason score at cryoablation, number of positive biopsy cores and use of neoadjuvant hormonal therapy before cryoablation.
Results: Serum prostate specific antigen at cryoablation was a predictive factor for biochemical recurrence on univariate and multivariate analysis (p <0.001). Patients with pre-cryoablation prostate specific antigen less than 4 ng/ml had a 5 and 8-year biochemical recurrence-free survival of 56% and 37%, respectively. In contrast, patients with pre-cryoablation prostate specific antigen 10 ng/ml or greater had a 5 and 8-year biochemical recurrence-free survival of only 1% and 7%, respectively. Patients with pre-cryoablation prostate specific antigen from 4 to 9.99 ng/ml had intermediate survival outcomes. Of the patients 32% were started on hormonal therapy for disease progression at a mean of 31 months postoperatively. Overall 5 and 8-year survival was 97% and 92%, respectively.
Conclusions: Salvage cryoablation is a viable treatment option for patients with prostate cancer in whom radiation therapy has failed. Salvage cryoablation should be performed when serum prostate specific antigen is still relatively low because in these patients the procedure may potentially be curative. Even when cryoablation fails to eradicate the disease in some patients, it allows hormonal therapy to be deferred for a significant period of time in that cohort.