[1053] Prostate Cancer within 0.01 cm of a Negative Surgical Margin of a pT2 Prostatectomy Specimen Predicts Recurrence

Lawrence D True, Jason P Izaard, Vakar-Lopez Funda, Rodney Schmidt, William J Ellis, Paul H Lange, Daniel W Lin, Bruce Dalkin, Jonathan L Wright. University of Washington, Seattle, WA

Background: A positive surgical margin of a radical prostatectomy specimen (RP) is an independent predictor of biochemical recurrence (BCR) of prostate-confined carcinoma (PcPCa). Earlier studies failed to find that cancer close to the margin increased the probability of BCR. However, these studies were limited by either small sample size or large cancer to surgical margin distances. We hypothesized that PcPCa within 0.01 cm of a negative surgical margin is associated with an increased BCR rate.
Design: Since 1998, we recorded the margin status of all RP specimens in a prospective database. Between 1998 and 2005 we categorized the margin status of all pT2N0 prostate cancers as either “negative,” “close to” (between 2 to 6 cells from the margin), “virtually at” (≤ 2 cells from the margin) or “positive” (ink on the margin touching cancer). From 2005 to 2011 we used a template to subcategorize margin status as either "positive", "abuts" (within 0.01 cm of the margin) or "negative" (> 0.01 cm from the margin). Use of the template led to more consistent margin categorization. We included all men undergoing RP without neoadjuvant therapy and without detectable post-op PSA. We employed multivariate Cox regression analysis to determine if margin status was predictive of BCR, adjusting for Gleason score, age, race, adjuvant radiotherapy, and diagnostic serum PSA.
Results: Of 1588 patients who underwent RP, 12% had BCR (median follow-up 25 months). On multivariate analysis the frequency of BCR of patients with margins that “abuts” (HR 1.6, 95% CI 1.2-3.7) was close to that of patients with positive margins (HR 2.2, 95% CI 1.6-3.1). There was no difference in the frequency of BCR of patients with margins that were “virtually at” the cancer than of margins that were positive (HR 1.1, 95% CI 0.6-1.8).

BCR based on Margin Status
Margin statusFrequency (%)BCR (%)Hazard Ratio
Positive19192.9
Virtually at (≤ 2 cells)652.4
Abuts (< 0.1 mm)7121.6
Negative688NA



Conclusions: Prostate cancer that is within 0.01 cm of, but not at, the margin of a pT2 node-negative RP is associated with a BCR rate that is similar to that of patients with a positive surgical margin. We recommend that the margin status of cancers that are within 0.01 cm of a negative margin be reported as "cancer abuts the margin." A readily available "ruler" to categorize margin status is a 40x objective; a linear distance of 0.1 mm occupies 1/5th of the field diameter of most 40x objectives.
Category: Genitourinary (including renal tumors)

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 77, Tuesday Morning

 

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