Salvage cryotherapy for locally recurrent prostate cancer following primary radiotherapy is curative in approximately one-third of men after 10 years of follow-up, according to results from a retrospective chart review investigating long-term treatment outcomes.
The finding may help address the clinical challenge inherent in managing men with locally recurrent prostate cancer after primary radiation therapy, say researchers from the University of South Florida, Tampa, who reported the data at the AUA annual meeting here.
"Cryotherapy is one treatment option, but there has been limited information in the literature about its long-term outcomes," said Omar Hamoui, MD, a University of South Florida urology resident working with Philippe E. Spiess, MD, and colleagues. "Our study is distinguished from existing reports by the length of our follow-up, and we believe our long-term results support the clinical utility of salvage cryotherapy for this patient population."
The study included 110 patients who had been treated with salvage cryotherapy at the University of Texas M.D. Anderson Cancer Center, Houston. All men had biopsy-proven locally recurrent prostate cancer and were followed every 3 months with determination of serum PSA. The median follow-up after salvage cryotherapy was 7.9 years.
Biochemical failure, defined as a serum PSA >0.5 ng/mL, was analyzed as the primary endpoint of the study. By 1 year, the biochemical failure rate was already high at 58%. At 5 years it reached 74%, but then increased only slightly to 83% at 10 years. Disease-specific survival rates for the population were 87% at 5 years and 63% at 10 years.
"These data are helpful to practicing urologists because they provide insight into how well patients do over the long term after salvage cryotherapy for locally recurrent prostate cancer after primary radiotherapy," said Dr. Spiess, assistant professor of urologic oncology at H. Lee Moffitt Cancer Center, Tampa. "The results suggest that, in its current form, cryotherapy is a feasible treatment option for these men, although based on a comparison with historical data, cryotherapy remains inferior to salvage prostatectomy.
"Our data on biochemical failure rates indicate that PSA monitoring can be used to determine at an early stage patients who are going to fail. At that time, they can be considered for other treatment, such as hormonal ablative therapy or chemotherapy."
Limited contemporary technology
The investigators pointed out that an important limitation of their study is that the cohort was not treated with contemporary cryotherapy technology. The patients in the series were treated between 1992 and 2004, when only second-generation cryotherapy equipment was available.
"We are now using third-generation cryotherapy devices, and so our long-term results will need to be validated for the use of the newer technology," Dr. Spiess said. "Some papers have reported early outcomes, including one multicenter study published 2 years ago and a few more recent articles, and their results indicate that biochemical-free and disease-specific survival rates are not any better using the newer equipment. However, there appears to be some clinical benefit in terms of reduced morbidity."
Consistent with other reports on salvage cryotherapy, the morbidity of salvage cryotherapy in the M.D. Anderson population most commonly included mild/moderate urinary incontinence (39%), severe urinary incontinence (41%), and urinary retention (34%). In addition, men experienced problems with impotence, retrourethral fistulae, perineal pain, and hematuria.
Preliminary analyses were conducted to examine predictors of long-term outcome for salvage cryotherapy. The results of univariate analyses showed initial PSA >10.0 ng/mL, initial biopsy Gleason score >8, and use of a single freeze-thaw cycle during cryotherapy were significant predictors of subsequent biochemical failure and disease outcome.
"Due to the high proportion of patients who failed early, we were not able to perform multivariate analyses of variables predicting outcome. However, the prognostic factors we identified in univariate analysis are consistent with those reported to be independent predictors of outcome in studies with shorter follow-up," Dr. Spiess said.