Oncological Impact of Gross Proximal Margin Length in Distal Gastrectomy for Gastric Cancer: Is the Japanese Recommendation Valid?

OBJECTIVE: To identify an oncological impact of gross proximal margin (PM) length in distal gastrectomy for cancer. SUMMARY BACKGROUND DATA: In Japan, to obtain pathologically negative PMs in gastrectomy for cancer, the Gastric Cancer Treatment Guidelines (GCTGs) recommend maintaining the PM length to at least 2 cm for cT1, 3 cm for the expansive growth type (Exp), and 5 cm for the infiltrative growth type (Inf) of cT2–4. The GCTGs also recommend confirming pathologically negative PMs by intraoperative frozen section analyses when the gross PMs are shorter than the recommendations. However, whether they are valid is unknown. METHODS: Patients who intended to undergo curative distal gastrectomy were included. They were divided into groups A (adherence to the GCTGs) and NA (nonadherence) according to the PM length. The incidence of pathologically positive PMs and survival outcomes were compared between the groups. Propensity scores (PSs) were used in comparisons of survival outcomes to eliminate potential confounders. RESULTS: A total of 1036 patients were eligible. Pathologically positive PMs were identified in group NA with cT1 and Inf, and the incidence was 1.6% and 3.1%, respectively. Adjusted analysis using the PSs showed comparable survival outcomes between the groups. However, the hazard ratios according to the PSs presented a possible survival advantage in maintaining the recommended gross PM lengths except for cT1 and Exp located in the lower stomach. CONCLUSION: Surgeons should maintain the gross PM lengths recommended in the GCTGs to both obtain pathologically negative PMs and avoid survival disadvantages.