BERKELEY, CA (UroToday.com) - Positive surgical margin (PSM) is an established risk factor for biochemical recurrence (BCR) after radical prostatectomy (RP).
Since not every patient with PSM would have BCR, there was an ongoing search for additional PSM parameters allowing for more accurate risk stratification. Initially PSM location was studied and apical margins were felt to confer less risk of BCR. Evaluation of PSM extent using crude categories (focal versus extensive) also provided promising but inconsistent across series findings. Recently, PSM length emerged as a more accurate parameter and some urological pathologists adopted its routine measurement.
Because clinical decision-making requires categorization, different thresholds of PSM length were explored with regard to associated risk of BCR in the series from the University of Chicago and other institutions. In our initial report (J Urol. 2009 Jul) we found that PSM <1 mm may not confer additional BCR risk as compared to a negative margin, however this subgroup analysis was underpowered. In order to evaluate further this assertion we published a follow-up series (BJU Int. 2012 Jul) of larger sample size and longer follow-up. Our analyses showed that PSM <1 mm is associated with twice higher risk of BCR after adjustment for stage, grade, and PSA in multivariable model. Looking closely at different thresholds we identified that margin length over 3 mm is the most prominent risk factor for BCR. Subgroup analyses by Gleason score showed significant differences in BCR rates suggesting that Gleason grade at the margin may also play a role which should be assessed in the future.
As an aside, a few words about methodology. It matters, and the fact that we did not confirm our initial assertion in the follow-up study with more robust design is a perfect example. Furthermore, in the presence of multiple confounding factors such as PSA, stage, Gleason score, and possibly grade at the margin, the need for a sound multivariable modeling calls for large sample size, long follow-up time, and prospective measurement of margin length and grade at the margin.
Written by:
Sergey Shikanov, 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 Surgery
University of Chicago Hospitals
Chicago, IL
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