Pathological staging criteria for carcinoma in the remnant stomach: an exploratory study

Abstract

To explore the prognostic value of the tumor-ratio-metastasis (TRM) staging system for carcinoma in the remnant stomach(CRS). Clinicopathological data of 91 CRS patients who underwent surgery at Peking University People's Hospital between March 1992 and December 2017 were retrospectively analyzed. According to the ratio of metastatic lymph node to dissected lymph node, the R staging was obtained, and the pN staging was replaced by the R staging to create the TRM staging. To compare the predictive accuracy of TRM and tumor-node-metastasis (TNM, UICC version 7), the R staging and pN staging were included in the prognostic factor analysis model, and the survival curve, c-index, and 95% confidence interval (CI) of the TRM staging and TNM staging system were compared. A higher c-index value means higher prediction accuracy. Of 91 CRS patients, 77 were male and 14 were female with the mean onset age of (65.2±10.4) years. The mean interval from the first operation to CRS onset was 156(6-600) months. The primary diseases of 49(53.8%) cases were benign and of 42(46.2%) cases were malignant. The median number of retrieved lymph node (RLN) was 8 (0-38), and 64 patients (70.3%) had an RLN ≤15. Lymph node metastasis occurred in 50 patients (54.9%). pN staging result was as follows: 41 cases in N0 stage, 14 in N1 stage, 19 in N2 stage, and 17 in N3 stage. R staging result was as follows: 41 cases in R0 stage, 4 in R1 stage, 19 in R2 stage, and 27 in R3 stage. TNM staging result was as follows: 13 cases in stage I(, 25 in stage II(, 10 in stage III(a, 23 in stage III(b, and 6 in stage III(c. TRM staging result was as follows: 13 cases in stage I(, 24 in stage II(, and 4 in stage III(a, 18 in stage III(b, and 18 in stage III(c. Univariate analysis showed that tumor diameter ≥7 cm (HR=2.696, 95%CI: 1.307-5.563, P=0.007), T3-4 stage (HR=4.350, 95%CI: 1.949-9.707, P=0.000), N2-3 stage (HR=1.883, 95%CI: 1.167-3.038, P=0.009), R2-3 stage (HR=1.642, 95%CI: 1.026-2.628, P=0.039), TNM III(-IIII( stage (HR=2.448, 95%CI:1.490-4.021, P=0.000), and TRM III(-IIII( stage (HR=2.504, 95%CI:1.515-4.137, P=0.000) were related to prognosis. Tumor diameter, pT staging, and pN staging were included in the Cox multivariate analysis, and the result showed that pT staging (HR=5.507, 95%CI:2.254-13.454, P=0.000) and pN staging (HR=1.698, 95%CI: 1.022-2.789, P=0.041) were independent risk factors for overall survival of CRS in this group. While R staging replaced pN staging and was included in the Cox multivariate analysis together with tumor diameter and pT staging, the result showed that R staging was not an independent risk factor for CRS in this group (HR=1.622, 95%CI: 0.866-2.329, P=0.164). Survival curve revealed pN and TNM staging systems provided better stratified curves according to each staging than R and TRM staging systems. The overall survival c-index of TNM and TRM staging systems was 0.813(95%CI: 0.732-0.826) and 0.809(95%CI: 0.741-0.847) respectively, and no significant difference in predictive accuracy was found (P=0.693). In 42 patients with primary malignance, the overall survival c-index of TNM and TRM staging systems was 0.774(95%CI: 0.589-0.901) and 0.761(95%CI: 0.596-0.912) respectively, and there was no significant difference in predictive accuracy as well (P=0.881). TRM staging is not superior to TNM staging (7th UICC) in evaluating the resected samples of CRS.