Impact of positive surgical margin length and Gleason grade at the margin on oncologic outcomes in patients with nonorgan-confined prostate cancer

PURPOSE: Positive surgical margins (PSM) represent a poor prognostic factor at radical prostatectomy (RP). To investigate the impact of PSM, its length, the focality and the Gleason grade at the PSM, on the oncologic outcomes in nonorgan-confined RP patients.

METHODS: Within a high-volume center database, we identified patients who harbored non-organ-confined (pT3) prostate cancer (PCa) at RP between 2010 and 2016. Only patients without lymph node invasion were included. Kaplan-Meier analyses and multivariable Cox regression models were used to test the effect of PSM on biochemical recurrence (BCR), metastasis, and cancer-specific death after RP in patients without adjuvant radiotherapy.

RESULTS: Overall, 3705 patients were identified. Of those, 27.2% (n = 1007) harbored PSM. At 96 months after RP, BCR-free, metastasis-free and cancer-specific survival was 41.6 versus 57.5%, 82.7 versus 88.6%, and 94.7 versus 98.5% for patients with versus without PSM (all p < 0.001). BCR-free, metastasis-free and cancer-specific survival rates at 96 months were 56.7 versus 26.5% (p < 0.001), 94.4 versus 67.4% (p < 0.001), and 100.0 versus 87.1% (p < 0.01) for Gleason pattern 3 versus ≥ 4 at the margin and 45.0 versus 27.8% (p < 0.01), 83.3 versus 82.3% (p = 0.2), and 95.2 versus 92.7% (p = 0.3) for <4 mm versus ≥4 mm length of margin. In multivariable Cox models PSM was an independent predictor for BCR (hazard ratio [HR]:1.53, p < 0.001) and cancer-specific death (HR:2.75, p = 0.02). In subgroups of patients with PSM only, Gleason ≥ 4 at the margin (HR:1.60, p < 0.01) and length of PSM (HR:1.02, p < 0.05) was an independent predictor of BCR.

CONCLUSION: PSM represents an independent predictor for worse oncologic outcome in nonorgan-confined PCa at RP. Gleason ≥ 4 at the margin was associated with the development of BCR, metastasis, and with cancer-specific death after RP. Next to margin status, Gleason at the margin and its length carry important information that should be reported for the specimen.