Identification of patients with lymph node metastasis from gastric cancer who may benefit from adjuvant chemoradiotherapy after D2 dissection-Do N3 patients benefit from additional radiation?

Objective: The role of adjuvant chemoradiotherapy (CRT) in locally advanced gastric cancer (LAGC) after D2 dissection is controversial. Subgroup analysis of the ARTIST trial indicated that patients with lymph node metastasis might benefit from additional radiation. The present study compared adjuvant CRT with adjuvant chemotherapy (CT) for the treatment of lymph node metastasis and suggested patient-selection guidelines. Methods: Patients with LAGC and positive lymph nodes who underwent D2, R0 gastrectomy in our hospital were retrospectively investigated. Patients were divided into two balanced groups by the use of propensity-score matching: CRT group (n=138) received adjuvant CRT with fluorouracil-based regimens and radiation (45-50.4Gy), and the CT group (n=138) received adjuvant CT alone. Results: Of the 276 patients, 147 patients died (69 patients in the CRT group and 78 patients in the CT group), and 151 patients experienced recurrence (65 patients in the CRT group and 86 patients in the CT group). The estimated 3-year disease-free survival (DFS) and overall survival in the CRT and CT groups were 51.5% vs 41.3% (p=0.05) and 52.0% vs 50.1% (p=0.35), respectively. The risk of local regional recurrence was increased in the CT group compared with the CRT group (16.7% vs 8.7%, p=0.04, respectively). In the subgroup analysis, patients with N1-2 stage were associated with better survival from CRT (hazard ratio=0.44, p=0.01). Conclusion: Adjuvant CRT may improve the 3-year DFS and local control in patients with LAGC after D2 dissection. Investigation of stratification factors for patient selection is warranted. Advances in knowledge: Patients with N1-2 stage rather than those with N3 stage benefit most from additional radiation after D2 dissection.