Comparison of two different adjuvant treatment modalities for pN3 gastric cancer patients after D2 lymph node dissection: can we avoid radiotherapy in a subgroup of patients?

Adjuvant chemoradiotherapy (CRT) is the standard of care for gastric cancer patients in the USA. However, in countries where D2 lymph node dissection is performed, the effect of radiotherapy on locoregional recurrence is controversial. The aim of this study is to compare the outcomes in pN3 gastric cancer patients following two adjuvant treatment modalities: chemotherapy (CT) and CRT after D2 lymph node dissection. Between 2005 and 2009, 71 gastric cancer patients who underwent D2 lymph node dissection and had pTanyN3M0 stage (according to AJCC 6th edition) were identified. Fifty-three patients were treated with CT and 18 patients received CRT. CRT consisted of bolus fluorouracil (FU) 425 mg/m² and leucovorin 20 mg/m² before, after, and during radiotherapy. For the CT arm, treatment protocols consisted of combination therapies involving FU and cisplatin as the backbone. Median overall survival (OS) and disease-free survival (DFS) rates for all patients were 26.3 months (15–37.7 months) and 12.5 months (8–17.1 months). Median OS in CT arm was 26.8 months and it was 34.2 months for CRT arm (p = 0.74). DFS rates did not differ statistically either (p = 0.56, 12.5 and 15.2 months for CT and CRT, respectively). Locoregional recurrence rates were also similar (p = 0.63). Only metastatic/dissected lymph node ratio (≥0.75) was identified as a prognostic factor in both univariate and multivariate analyses for DFS. Comparison of CT versus CRT for N3 stage gastric cancer patients with D2 lymph node dissection did not reveal any statistically significant difference in survival rates and locoregional recurrence.