Prognostic value of subclassification of pT2 stage in patients with gastric cancer.

Abstract

e16070 Background: The data about prognosis difference of patients with pT2 stage gastric cancer (GC) after radical surgery is diverse. The latest TNM staging system does not define details for the pT2 stage subclassification. The purpose of this study is to investigate the survival difference according to depth of tumor muscularis propria involvement and find biomarker to reinforce the prognostic and therapy-guided ability of TNM staging system. Methods: A total of 380 patients with pT2 GC after radical surgery were retrospectively analyzed, including 185 in sMP (superficial muscularis propria) group and 195 in dMP (deep muscularis propria) group. The log-rank test was used to identify survival outcomes. Independent factors were identified by multivariable Cox proportional hazard model for OS. Results: The overall survival (OS) of patients in sMP group was significantly better than patients in dMP group (P = 0.007). On multivariate analysis, age (＜60 vs ≥60: P = 0.004, HR, 2.075(95%CI: 1.261-3.414)), primary location (P = 0.002, U vs M: 0.985(0.509-1.909); U vs L: 0.400(0.235-0.680)), depth of tumor invasion (sMP vs dMP: P = 0.050, 1.584(1.261-3.414), pN stage (P = 0.000, N0 vs N1: 2.304(1.364-3.890); N0 vs N2: 1.879(0.967-3.652); N0 vs N3: 5.335(2.533-11.237)), expression of p53 (negative vs positive: P = 0.016, 1.793(1.117-2.879)) were independent prognostic factors for the OS. In pN0 stage tumor, the sMP group had a significantly better OS than the dMP group (P = 0.014). When classified as N+, there was no obviously difference of OS between two groups (P = 0.384). When patients were stratified according to the depth of tumor invasion and pN stage, the OS was not significant difference between dMPN0 group and sMPN1-2 group (P = 0.100), the OS of patients with adjuvant chemotherapy were statistically better than those without in dMPN0 group (P = 0.045), but not significance in sMPN1-2 group (P = 0.486). After further grouping according to adjuvant chemotherapy status, in comparison to sMPN1-2 patients, dMPN0 patients with adjuvant chemotherapy had better OS (P = 0.015), but not significance in patients without (P = 0.599). Upon stratification according to the expression of p53, in p53-positive group, greater OS could be observed in patients with sMPN0 than patients with dMPN0 (P = 0.002). Similar OS could be seen between dMPN0 patients with p53-positive and T2N1-2 patients (P = 0.872). Conclusions: For pT2 gastric cancer patients, there were differences in survival outcomes for sMP and dMP invasion. The prognosis of dMPN0 patients were similar to patients with sMPN1-2, and dMPN0 patients who accepted adjuvant chemotherapy had an improved prognosis than those without. Appropriate adjuvant chemotherapy should be considered for patients with dMPN0 stage. In addition, positive expression of p53 could be potential factors to identify the different prognoses for patients with pT2 gastric cancers.