Cancer cells invasion to the gastric bare area adipose tissue: a poor prognostic predictor for gastric cancer

Background The relationship between gastric bare area adipose tissues invasion (GBAI) confirmed pathologically and the prognosis of gastric cancer (GC) patients is undefined. Till present, there has not been literature investigating this phenomenon. Here, we aimed at analyzing the implication of GBAI in GC. Methods The data of 1822 patients who underwent radical surgery between January 2000 and December 2013 at the Sun Yat-sen University Cancer Center were retrieved. Pathologically, tumor deposits (TDs) located > 5 mm from the leading edge of the primary tumor and the lymph nodes (LNs) station number 1, 2, 7, and 9 were considered GBAI. Kaplan-Meier method, log-rank test, and Cox's proportional hazards model were employed to analyze. Results Two hundred and five (11.3%) patients were pathologically diagnosed with GBAI, which was more commonly found in proximal or linitis lastica than distal GC (P < 0.001). There was significant difference in 5-year survival between patients with and without GBAI for stages IIB, IIIA, IIIB, and IIIC, respectively (P < 0.009 for IIB, IIIA, and IIIB; P = 0.021 for IIIC). Among the 205 GBAI patients, 61 had detailed radiological follow-up data in which 26 (34.7%) were found to have retroperitoneal infiltration, 27 (36.0%) had peritoneal metastasis, 10 (13.3%) had hematogenous metastasis, 16 (21.3%) had lymphatic metastasis, and 16 (21.3%) had others. Conclusions GBAI was identified as a predictor of unfavorable prognosis for GC and was more commonly found in the proximal or linitis plastica of the stomach than in distal stomach. Retroperitoneal infiltration was one of the most commonly identified metastatic route for GC associated with GBAI after radical surgery.