Adjuvant chemoradiotherapy versus adjuvant chemotherapy for R1 resected gastric cancer: a retrospective cohort study.

Objective: The aim of this study was to compare the effects of adjuvant chemoradiotherapy (CRT) and adjuvant chemotherapy (ChT) on the survival of locally advanced gastric cancer (LAGC) patients treated with R1 resection. Methods: The patients with LAGC and microscopically positive margins after a potentially curative gastrectomy in Fudan University Shanghai Cancer Centre were retrospectively identified. The patients who were referred to our hospital for adjuvant CRT after an R1 resection elsewhere were also included. The patients were divided into either the CRT group or ChT group according to the treatment strategy. We, then, examined the patient survival results and patterns of recurrence for each group. Results: There were 114 LAGC patients treated with an R1 resection identified (CRT, n = 33; ChT, n = 81). The baseline characteristics between the two groups were not different. The estimated 3 year recurrence-free survival and overall survival in the CRT and ChT groups were 45.1% vs 31.8% (p = 0.09) and 49.6% vs 39.4% (p = 0.20), respectively. The results indicated that only nodal status was an independent prognostic factor (hazard ratio 4.04, 95% confidence interval 2.06-7.93). The risk of locoregional recurrence was increased in the ChT group. The subgroup analysis revealed that patients with pN0-2 GC showed a better recurrence-free survival due to adjuvant CRT (hazard ratio 0.19, 95% confidence interval 0.04-0.90; p = 0.022). Conclusion: Adjuvant CRT improves locoregional control and may benefit patients with pN0-2 GC after R1 resection. The nodal status may be the most important predictor for patient selection. Advances M knowledge: Nodal status may be the most important predictor for patient selection. Compared with adjuvant ChT, LAGC patients with pN0-2 disease may further benefit from additional radiotherapy after R1 resection.