Close surgical margins after radical prostatectomy mimic biochemical recurrence rates of positive margins

Introduction: The significance of a "close" but negative surgical margin after radical prostatectomy (RP) is controversial. We evaluated the effect of a close surgical margin (CSM) on biochemical recurrence (BCR) compared to a negative margin after RP. Materials and methods: Pathologic records of men who underwent RP from 2005-2011 were retrospectively reviewed. Margin status was classified as "positive" (PSM), "negative" (NSM), or "close" (<1. mm from margin). BCR was defined as 2 consecutive postoperative prostate specific antigen measurements >0.2. ng/ml. Probability of BCR was estimated using the Kaplan-Meier method and stratified by margin status. Univariable and multivariable Cox proportional hazards models were used to determine whether close margin status was associated with an increased rate of BCR. Results: A total of 609 consecutive patients underwent RP (93% robotic) and had complete pathologic data. A total of 126 (20.7%) had PSM, 453 (74.4%) had NSM, and 30 (4.9%) had CSM (mean<0.44. mm). The 3-year BCR-free survival for patients with CSM was similar to those with PSM (70.4% vs. 74.5%, log rank P = 0.66) and significantly worse than those with NSM (90%, log rank P<0.001). On multivariable regression, positive margin status (HR = 3.26, P<0.001) was significantly associated with a higher risk of BCR, along with close margins (HR = 2.7, P = 0.04). Conclusions: BCR for patients with CSM at RP is tantamount to PSM patients. CSM <1. mm should be explicitly noted on pathology reports. Patients with this finding should be followed up closely and offered adjuvant therapy.