Impact of positive surgical margins on biochemical recurrence and metastases after radical prostatectomy.

[OBJECTIVES] To evaluate the impact of the presence, extent and location of positive surgical margins (PSMs) on the risk of biochemical recurrence (BCR) and metastases in a nationwide cohort of patients who underwent radical prostatectomy (RP) and had 5 years of follow-up.

[METHODS] All patients diagnosed with prostate cancer in the Netherlands between October 2015 and April 2016 who underwent RP were included in a prospective cohort. Data on these patients from the Netherlands Cancer Registry and the PALGA pathology registry were analysed. BCR was defined as a prostate-specific antigen (PSA) level ≥0.1 ng/mL >28 days after RP. Exclusion criteria were (neo)adjuvant treatment, pN1 disease, and salvage therapy initiated at PSA <0.1 μg/L. Multivariable Cox regression analyses were performed to evaluate the impact of PSM presence, extent and location on the risk of BCR and metastases.

[RESULTS] Of 998 patients, 311 (31%) had PSMs (median length 5.0 mm). Over 5 years of follow-up, 36% of patients experienced BCR and 11% developed metastases. PSMs ≥3 mm were associated with a significantly increased risk of BCR (hazard ratio [HR] 2.04, 95% confidence interval [CI] 1.58-2.64; P < 0.001) and metastases (HR 2.12, 95% CI 1.21-3.74; P = 0.009) compared to negative surgical margins. By contrast, PSMs <3 mm and PSM location did not significantly increase the risk of BCR or metastases.

[CONCLUSION] Our study showed that PSMs ≥3 mm appear to be independently associated with an increased risk of BCR and metastases after RP. Therefore, avoiding or limiting the extent of PSMs during RP remains essential.