BERKELEY, CA (UroToday.com) - Although cryosurgery has emerged in recent years to one of the standard treatment options available to patients with prostate cancer, difficulty still exists to assess patients after the procedure with regards to their prostate response reflected in post-operative PSA levels. In contrast to radical prostatectomy, prostate tissue, and consequently also PSA production, may persist after cryosurgery of the prostate, and may not necessarily represent persistent cancer tissue, which leads to the difficulty in defining biochemical recurrence (BCR).
| "...this study elucidates existing BCR definitions, adds new ones, and exemplifies that different definitions may be best suitable for different subsets of patients in different prostate cryosurgery settings." |
For many years, research had been dedicated to assessing patients after radiotherapy and trying to define optimal PSA nadir and PSA cut-off levels to accurately define BCR, and to decide on whether a prostate biopsy is indicated to prove local disease recurrence. Several definitions for BCR after radiotherapy have been established. Although a completely different treatment approach and technique, those definitions were ultimately also applied to patients after cryosurgery, but they have never been validated in this setting. Hence, there has been a paucity of studies addressing cryosurgery-specific definitions of BCR after treatment. Several other groups have studied various predictive variables in the post-cryosurgery setting: e.g. PSA-doubling time, time to undetectable PSA (Case et al., 2010), PSA nadir (Shinohara et al., 1997; Levy et al., 2009 and 2001); and one of the biggest studies on patients undergoing salvage cryosurgery of the prostate after failed primary radiotherapy, also from Columbia University Medical Center, by Wenske et al. published in July 2012 in European Urology, found only PSA nadir to be predictive of disease recurrence in multivariate analyses.
The study by Pitman et al. from Columbia University Medical Center in New York, published online in May 2012 in Prostate, addressed several different definitions of PSA recurrence after cryosurgery and correlated these with post-cryosurgery biopsy results. Aim of that study was to determine accuracy of those BCR definitions in predicting biopsy-proven local recurrence following prostate cryosurgery. In particular, the study aimed mainly at investigating the most frequently used BCR definitions after radiotherapy, i.e. ASTRO and Phoenix definition, in the post-cryosurgery setting.
Overall, the findings of this study showed that the Phoenix definition was most accurate in the prediction of biopsy-proven local recurrence. This finding also held true when stratifying the patients by procedure type (i.e. primary focal gland cryosurgery, and salvage cryosurgery); for patients with primary full-gland cryosurgery a new BCR definition (nadir PSA plus 3 ng/ml) was found to be most accurate in the prediction.
The authors conclude that the Phoenix definition is still one of the most accurate ones to predict recurrence after cryosurgery, and different definitions may need to be validated and applied to different subsets of patients who undergo primary or salvage, focal or full gland ablative procedures.
Major limitation of the study by Pitman et al. with its retrospective design is the small number of patients; when stratified into subgroups, this number diminished even more. However, this might have at least partially been due to the fact that this group used strict inclusion criteria: all patients needed to have biopsy-proven local prostate cancer recurrence, which is certainly the most accurate way of confirming disease recurrence, but may have missed patients with disease recurrence that simply did not meet the institutional PSA/ BCR criteria of this group to trigger a biopsy after cryosurgery.
However, this study elucidates existing BCR definitions, adds new ones, and exemplifies that different definitions may be best suitable for different subsets of patients in different prostate cryosurgery settings.
Written by:
Sven Wenske, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Department of Urology
Columbia University Medical Center
161 Fort Washington Avenue
New York, NY 10032
More Information about Beyond the Abstract