Benefit of adjuvant chemoradiotherapy in patients with pathological stage III gastric cancer.

Background: For patients with locally advanced gastric cancer (LAGC) after D2 gastrectomy, the survival benefits of receiving adjuvant chemoradiotherapy versus adjuvant chemotherapy are unclear. This study aimed to compare the 5- and 7-year overall survival (OS) in the two groups and to identify which patients can benefit more from adjuvant chemoradiotherapy.

Methods: Retrospective data were collected from January 2009 to December 2014. The 5- and 7-year OS and disease-free survival (DFS) were compared between the two groups using the Chi-square test. The association of OS with prognostic factors was identified using the Cox's proportional hazard model, which was then adjusted for survival coparison using propensity score-matching (PSM) analysis. The association of OS with each clinical/demographic factor was compared between the two groups using the Kaplan-Meier analysis.

Results: A total of 415 eligible patients were identified (135 adjuvant chemoradiotherapy, 280 adjuvant chemotherapy). Significant 5- and 7-year OS and DFS benefits were found in the adjuvant chemoradiotherapy group versus chemotherapy group. Multivariate analysis showed that age, TNM stage, lymph node (LN) ratio, tumor deposits, and total/subtotal gastrectomy were independent prognostic factors. When the PSM analysis was adjusting by these factors, 135 patients were matched with an improved survival benefit from adjuvant chemoradiotherapy. Patients in the adjuvant chemoradiotherapy group had a lower locoregional relapse. Subset analysis also identified significant OS benefits of adjuvant chemoradiotherapy in patients with LN ratio <50%, pIIIA, and pIIIB stage disease, while OS benefits were not observed in patients with tumor deposits, pN3b classification, or pIIIC stage disease.

Conclusion: Adjuvant chemoradiotherapy was shown to be superior in improving the OS in a certain population of patients compared with adjuvant chemotherapy. This finding may help to better guide the individualized treatments of patients with stage III LAGC after D2 gastrectomy.