Based on pN-stage to Identify Gastric Carcinoma Patients with Overall Survival Benefit from Postoperative Radiotherapy: A Propensity Score Matching Analysis and Subgroup Analysis

Abstract

Background: It is currently controversial whether regional lymph node status is related to the benefit of postoperative radiotherapy for gastric cancer. Methods: All surgically treated patients with more than 15 lymph nodes examined diagnosed by positive histology between January 2007–December 2019 were included from the SEER database. All the patients receiving adjuvant chemotherapy were subsequently compared by propensity score matching (PSM), with overall survival (OS) as the endpoint, adjuvant radiotherapy (ART) as the only variable. Results of subgroup analyses are presented in a forest plot. Results: There are 1882 patients included in this study, 1301(69.1%) patients in the ART group and 581(30.9%) patients in the no-ART group. After PSM, each group included 573 patients. Overall, ART did not significantly improve 3-year overall survival (OS; 55.5% vs 51.1%, p = 0.07). However, in the subgroup of patients with pathologic lymph node metastasis (pN₃-stage), 55-70 years old, tumor size > 89mm and T₃-stage benefited from postoperative radiotherapy (p < 0.05). We further performed PSM and survival analysis on total patients with different pathological lymph node stages to validate the role of ART. We statistically observed survival benefits in pN₊ (positive pathologic lymph node) and pN₃ groups, but no similar effects were observed in pN₁ and pN₂ groups. For pN₀ groups, although the results showed no statistical significance, we believe that ART should not be performed. Conclusion: ART significantly improved prognosis in the patients with pN₃-stage. More researches are needed to further validate the role of ART for gastric cancer.