Individualized prediction of survival benefits from perioperative chemoradiotherapy for patients with resectable gastric cancer

Abstract

Background: The survival benefits of perioperative chemoradiotherapy (PCRT) and perioperative chemotherapy (PCT) for resectable gastric cancer (GC) patients remain unclear. This study aimed to compare the effects of PCRT and PCT in patients with resectable GC and develop a nomogram to evaluate the prognosis and disease risk of patients.

Methods: A total of 6890 patients with stage IB-IIIC GC from 2010 to 2015 were retrieved from the Surveillance, Epidemiology and End Results (SEER) database. Univariate Cox proportional hazards regression analyses were performed to evaluate the prognostic value of involved variables. A new nomogram was constructed based on development cohort and validated by an external validation cohort. The clinical practicability and accuracy were assessed by concordance index (C-index), calibration plot, and receiver operating characteristic (ROC) curve.

Results: A better prognosis was obtained for patients with stage III GC treated with PCRT compared with those treated with PCT. Additionally, patients with grade III/IV, diffuse type GC, distal gastric cancer (DGC), tumor size >34 millimeters, or positive lymph nodes were more likely to benefit from PCRT. Multivariate analyses indicated that age, grade, tumor size, T stage, N stage, and comprehensive treatment were independent covariates. Excellent agreement of calibration plots and good discrimination power were obtained using the nomogram. The nomogram achieved a better net benefit than the 8th edition AJCC TNM staging. An online version was built based on the nomogram for convenient clinical use.

Conclusion: The application of perioperative chemoradiotherapy should be determined according to the clinicopathological features of patients. Our nomogram provided a reliable tool for screening patients who were right for PCRT and evaluating individual survival benefits.

Keywords: chemotherapy; gastric cancer; prognosis; radiotherapy.

FIGURE 1

Flowchart of patient selection for this study

FIGURE 2

Kaplan‐Meier survival curves for patients with resectable gastric cancer in different subgroups, which are stratified by treatment strategies. The dotted lines indicate median survival time of patients. (A) OS for patients with stage III GC. (B) OS for patients with stage III GC in the grade III/IV subgroup. (C) OS for patients with stage III GC in the diffuse type subgroup. (D) OS for patients with stage III GC in the DGC subgroup. (E) OS for patients with stage III GC in the tumor size >34 mm subgroup. (F) OS for patients with stage III GC in the lymph node‐positive subgroup

FIGURE 3

Kaplan‐Meier survival curves for patients with resectable gastric cancer in different subgroups, which are stratified by treatment strategies. The dotted lines indicate median survival time of patients. (A) OS for patients with stage I B‐III C GC. (B) OS for patients with stage III GC in the grade I/II subgroup. (C) OS for patients with stage III GC in the intestinal type subgroup. (D) OS for patients with stage III GC in the PGC subgroup. (E) OS for patients with stage III GC in the tumor size ≤34 mm subgroup. (F) OS for patients with stage III GC in the lymph node‐negative subgroup

FIGURE 4

The prognostic nomogram and time‐dependent ROC curve for GC patients. (A) Prognostic nomogram predicting 1‐, 3‐, and 5‐year survival probability for patients with resectable GC using six clinical characteristics. For each predictor, the points assigned on the 0‐100 scale are read at the top, and then, these points are added. The number on the “Total Points” scale is located, and then, the corresponding predictions for 1‐, 3‐, and 5‐year survival probability are read. (B) The time‐dependent ROC curve for GC patients predicted by the new nomogram model (red line) and the 8th TNM staging system (blue line)

FIGURE 5

Development dataset of the nomogram for GC patients. (A) ROC curves for 1‐, 3‐, and 5‐year OS in the development cohort. (B) Calibration plots for 1‐, 3‐, and 5‐year OS in the development cohort. (C) DCA curves for 1‐, 3‐, and 5‐year OS in the development cohort

FIGURE 6

Online web server page of our nomogram