Clinical Impact of Positive Surgical Margins in Gastric Adenocarcinoma in the Era of Preoperative Therapy

Background Microscopically positive (R1) surgical margins after gastrectomy increase gastric cancer recurrence risk, but optimal management after R1 gastrectomy is controversial. We sought to identify the impact of R1 margins on recurrence patterns and survival in the era of preoperative therapy for gastric cancer. Methods Patients who underwent gastrectomy for adenocarcinoma during 1998–2017 at a major cancer center were enrolled. Clinicopathologic factors associated with positive margins were examined, and incidence, sites, and timing of recurrence and survival outcomes were compared between patients with positive and negative margins. Results Of 688 patients, 432 (63%) received preoperative therapy. Thirty-four patients (5%) had R1 margins. Compared with patients with negative margins, patients with R1 margins more frequently had aggressive clinicopathologic features, such as linitis plastica (odds ratio [OR] 7.79, p < 0.001) and failure to achieve cT downstaging with preoperative treatment (OR 5.20, p = 0.005). The 5 year overall survival (OS) rate was lower in patients with R1 margins (6% vs 60%; p < 0.001), and R1 margins independently predicted worse OS (hazard ratio 2.37, 95% CI 1.51–3.75, p < 0.001). Most patients with R1 margins (58%) experienced peritoneal recurrence, and locoregional recurrence was relatively rare in this group (14%). Median time to recurrence was 8.5 months for peritoneal dissemination and 15.7 months for locoregional recurrence. Conclusion R1 margins after gastrectomy were associated with aggressive tumor biology, high incidence of peritoneal recurrence after a short interval, and poor OS. In patients with R1 margins, re-resection to achieve microscopically negative margins has to be considered with caution.