Adjuvant chemoradiotherapy for stage III gastric cancer: A differential role in R0 and non-R0 resection

The role of adjuvant concurrent chemoradiotherapy (CCRT) in stage III gastric cancer remains unclear, particularly after D2 lymphadenectomy. While CCRT may benefit patients with residual disease, its value for patients with R0 resection remains uncertain. Accordingly, this study evaluated the survival effect of adjuvant CCRT in R0 and non-R0 resection groups.

We retrospectively reviewed the medical records of patients with stage III gastric adenocarcinoma who underwent gastrectomy with D2 lymphadenectomy between January 2011 and June 2024. Patients were stratified by resection margin (R0 vs non-R0) and receipt of adjuvant therapy. Propensity score matching (PSM) was performed to adjust for baseline imbalances. Overall survival (OS) was analyzed using Kaplan-Meier and Cox regression analyses.

A total of 559 patients were included, of whom 483 (86.4%) underwent R0 resection and 76 (13.6%) underwent non-R0 resection. Overall, 78.9% received adjuvant therapy, with CCRT more frequently used in the non-R0 group (28.9% vs 4.6%; p < 0.001). In the non-R0 resection group, both adjuvant chemotherapy and CCRT were associated with significantly improved OS, with CCRT demonstrating additional benefits over chemotherapy ( p = 0.039). After PSM, CCRT was associated with a nonsignificant trend toward improved OS (34.2 vs 28.4 months, hazard ratio: 0.55, 95% confidence interval: 0.26-1.15; p = 0.096) compared with chemotherapy. In matched patients with R0 resection, no survival benefit was observed with CCRT (24.1 vs 36.0 months, hazard ratio: 1.29, 95% confidence interval: 0.56-2.98; p = 0.550).

Adjuvant CCRT was associated with a trend toward improved survival in patients with non-R0 resection. However, it was not associated with additional survival benefits compared with chemotherapy in patients undergoing R0 resection after D2 lymphadenectomy, indicating that systemic therapy alone may be sufficient. These findings support the selective use of CCRT and underscore the need for prospective studies to optimize adjuvant strategies.