Prognostic effect of microscopically negative but close resection margin in gastric cancer.

Introduction: Microscopically positive resection margin (RM) following curative surgery has been linked to disease recurrence in gastric cancer (GC), but the impact of microscopically negative but close RM (CRM) remains unclear. This study aimed to evaluate the prognostic implications of a CRM of ≤0.5 cm in GC patients.

Methods: A retrospective review of the institutional GC database identified 1958 patients who underwent curative gastrectomy for pathologically proven GC between January 2011 and December 2015. The patients were categorized into CRM (RM ≤0.5 cm) and sufficient RM (SRM, RM >0.5 cm) groups. The impact of CRM on recurrence-free survival (RFS) and overall survival (OS) was analyzed compared to the SRM group.

Results: The cohort comprised 1264 patients with early GC (EGC, 64.6%) and 694 with advanced GC (AGC, 35.4%). Forty-four patients (2.2%) had RM of ≤0.5 cm. CRM was associated with worse RFS in AGC (5-year RFS in the CRM vs. SRM groups; 41.6% vs. 68.7%, p = 0.011); however, the effect on OS was not significant (p = 0.159). Multivariate analysis revealed that CRM was an independent prognostic factor for RFS (hazard ratio [HR] 2.035, 95% confidence interval [CI] 1.097-3.776). In AGC, the locoregional recurrence rate was significantly higher in the CRM group than in the SRM group (15.4% vs. 4.9%, p = 0.044).

Conclusion: CRM of ≤0.5 cm was a significant prognostic factor for RFS in GC patients and was associated with a significant increase in locoregional recurrence in AGC.