Serial histopathology results of salvage cryoablation for prostate cancer after radiation failure

Abstract

Purpose: There has been a paucity of long-term followup reports of cryoablation for prostate cancer. In particular, little is known regarding the long-term histological results following salvage cryoablation. We report serial biopsy results of up to 43 months on 106 patients who underwent cryoablation after radical radiotherapy failed.

Materials and methods: A total of 110 cryoablation procedures were done in 106 patients for biopsy proven, clinically localized radiation failure. Postoperatively transrectal ultrasound guided biopsy (usually 4 cores) was done at approximately 3, and/or 6, 12 and 24 months, and thereafter as indicated by prostate specific antigen, which was measured every 6 months.

Results: Of 818 biopsy cores a total of 23 (2.8%) from 15 patients (14.2%) were positive. Of the positive cores 73.9% were found within year 1 following cryoablation. Residual viable prostate glands and stroma were found in 42.4% and 27.4% of patients, respectively, at various time points. The frequency of various histological features, the most common being necrosis and fibrosis, was tabulated from the serial biopsy histology reports.

Conclusions: The results of serial biopsies have improved our understanding of the histopathological changes as well as the capabilities and limitations of salvage cryoablation. The biopsy positivity rate is acceptable, although the finding of persistent viable prostatic tissue in a substantial proportion of patients implies that vigilant long-term followup is mandatory.