Long-Term Prognostic Analysis of Chemoradiation Therapy Versus Chemotherapy after D2 Resection for High-Risk Gastric Cancer: Results From a Prospective Randomized Control Study.

Abstract

To explore the population of patients who could benefit from adjuvant radiation therapy (RT) and investigated the value of postoperative chemoradiation therapy (CRT) in patients with gastric cancer after D2 resection. This randomized clinical trial enrolled patients between October 1, 2011, and December 31, 2019. Patients with gastric cancer who underwent D2 gastrectomy were randomized (1:1) to receive postoperative CRT or adjuvant chemotherapy after surgery. The adjuvant chemotherapy group received 8 cycles of SOX (S-1 + oxaliplatin) chemotherapy. RT was given after 4 to 6 cycles of SOX chemotherapy. RT comprised 45 Gy in 25 fractions of 1.8 Gy over 5 weeks by intensity modulated RT concurrently with S-1 chemotherapy. The primary endpoint was 3-year disease-free survival (DFS). A total of 312 patients (median [IQR] age, 58 [50-64] years) were enrolled, including 157 patients randomized to the adjuvant chemotherapy group and 155 patients randomized to the adjuvant CRT group. The 3-year DFS was 66.7% for the control arm and 70.7% for the experimental arm (hazard ratio [HR], 0.82; 95% CI, 0.54-1.25; P = .35). We defined patients with pN stage ≥ N2 and extraperigastric lymph node metastasis as the high-risk group and the remaining patients as the low-risk group. The 3-year DFS rates for the high-risk group and the low-risk group were 59.3% and 76.8%, respectively (HR, 2.11; 95% CI, 1.39-3.22; P < .01). For high-risk patients, the 3-year DFS rates in the adjuvant chemotherapy and adjuvant CRT groups were 53.0% and 71.0%, respectively (HR, 0.53; 95% CI, 0.29-0.97; P < .05). More grade 3 and 4 acute toxic effects were observed in the adjuvant chemotherapy group than in the CRT group (41 patients [26.1%] vs 28 patients [18.5%]; P = .11), but the difference was not significant. Subgroup analysis of this randomized clinical trial revealed that high-risk patients can benefit from adjuvant CRT.