Wrong to be Right: Margin Laterality is an Independent Predictor of Biochemical Failure After Radical Prostatectomy

To examine the impact of positive surgical margin (PSM) laterality on failure after radical prostatectomy (RP). A PSM can influence local recurrence and outcomes after salvage radiation. Unlike intrinsic risk factors, a PSM is caused by intervention and thus iatrogenic failures may be elucidated by analyzing margin laterality as surgical approach is itself lateralized.

We reviewed 226 RP patients between 1991 and 2013 with PSM. Data includes operation type, pre/postoperative PSA, surgical pathology, and margin type (location, focality, laterality). The median follow-up was 47 months. Biochemical recurrence after RP was defined as PSA≥0.1 ng/mL or 2 consecutive rises above nadir. Ninety-two patients received salvage radiation therapy (SRT). Failure after SRT was defined as any PSA≥0.2 ng/mL or greater than presalvage. Kaplan-Meier and Cox multivariate analyses compared relapse rates.

The majority of PSM were iatrogenic (58%). Laterality was associated with differences in median relapse: right 20 versus left 51 versus bilateral 14 months (P<0.01). Preoperative PSA, T-stage, Gleason grade, and laterality were associated with biochemical progression on univariate and multivariate analyses. Right-sided margins were more likely to progress than left (hazard ratio, 1.67; P=0.04). More right-sided margins were referred for SRT (55% right vs. 23% left vs. 22% bilateral), but were equally salvaged. Only T-stage and pre-SRT PSA independently influenced SRT success.

Most PSM are iatrogenic, with right-sided more likely to progress (and sooner) than left sided. Margin laterality is a heretofore unrecognized independent predictor of biochemical relapse and hints at the need to modify the traditional unilateral surgical technique.