Early risk stratification after robot-assisted radical prostatectomy: the role of positive surgical margins.

Abstract

Introduction: Positive surgical margins (PSMs) after robot-assisted radical prostatectomy (RARP) are consistently associated with biochemical recurrence (BCR), yet their prognostic heterogeneity and functional implications remain debated. This study aimed to evaluate the oncological and functional impact of PSMs and to explore clinicopathological predictors of margin positivity.

Methods: We conducted a retrospective single-center study including 93 patients undergoing RARP. Surgical margin status, length, focality, and location were recorded. BCR was defined as PSA ≥0.2 ng/mL confirmed by two measurements. Functional outcomes (urinary continence and erectile function) were assessed at 6 months. Multivariable logistic regression identified predictors of PSM, and Kaplan-Meier analysis evaluated BCR-free survival.

Results: PSMs were identified in 48 patients (51.6%). During a median follow-up of 11 months, BCR occurred more frequently in patients with PSMs than in those with negative margins (20.8% vs 4.4%, p=0.018). PSMs were associated with significantly worse early BCR-free survival (log-rank p=0.013). Margin length ≥3 mm did not stratify early BCR risk. In multivariable analysis, ISUP Grade Group 3-5 was the only independent predictor of PSM (OR 0.25, p=0.044). No significant differences in urinary continence or erectile function at 6 months were observed according to margin status.

Conclusions: PSMs are associated with an increased risk of early biochemical recurrence, while early functional outcomes appear independent of margin status. Tumor biology, rather than surgical factors, emerges as the main determinant of margin positivity. These findings support a risk-adapted interpretation of PSMs and align with current guidelines favoring close surveillance and early salvage treatment over routine adjuvant therapy.