Researchers have identified the optimal PSA nadir following whole-gland salvage prostate cryoablation for recurrent prostate cancer that predicts which patients will have the best long-term biochemical progression-free survival (bPFS).

In a retrospective study using the Cryo On-Line Database (COLD), Evan Kovac, MD, of the Glickman Urological and Kidney Institute at Cleveland Clinic, and colleagues analyzed outcomes among 486 hormone-naïve patients who underwent salvage whole-gland cryoablation following primary radiotherapy. They used Kaplan-Meier (KM) analysis to calculate 5-year bPFS using Phoenix criteria (PSA nadir plus 2 ng/mL).

KM analysis identified a nadir PSA of less than or greater than 0.4 ng/mL as the nadir PSA threshold, with the greatest difference in bPFS. The KM estimated 5-year bPFS rates were 75.5% and 22.1% for PSA nadir less than 0.4 and 0.4 ng/mL or higher, respectively, Dr Kovac’s group reported online ahead of print in the Journal of Endourology.

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The researchers stratified bPFS by presalvage PSA (psPSA). Among patients with a PSA nadir below 0.4 ng/mL, the estimated 5-year bPFS rates were 78.5%, 77.1%, and 77.8% for patients with a psPSA less than 4, 4–10, and more greater than 10 ng/mL, respectively. Among patients with a PSA nadir of 0.4 ng/mL or higher, rates were 17.9%, 15.7%, and 16.8%, respectively.

The study cohort had a median age of 72 years and mean and median psPSA of 6.09 and 4.7 ng/mL, respectively.

Noting that, historically, the preferred salvage therapy for men with an intact prostate has been radical prostatectomy (RP), the researchers said they believe “that salvage prostate cryotherapy represents a viable alternative to salvage RP, and previous studies have reported similar disease-specific survival rates following salvage RP and salvage cryotherapy. The results of our analysis suggest that salvage cryoablation may be beneficial to patients with a wide range of psPSA values and who reach a postsalvage PSA nadir <0.4 ng/mL.”

The authors noted that the retrospective nature of their analysis, which lends itself to inherent biases, was a limitation of their study. They also noted that the COLD registry does not contain information on salvage cryotherapy biopsy findings, which would provide more definitive proof of treatment success. Longer follow-up may allow for metastasis-free, disease-specific and overall survival rate analyses, which are more meaningful endpoints, according to the researchers.