Observational Study Comparing Efficacy and Safety between Neoadjuvant Concurrent Chemoradiotherapy and Chemotherapy for Patients with Unresectable Locally Advanced or Metastatic Gastric Cancer

OBJECTIVE: Dismal outcomes in patients with locally advanced or metastatic gastric cancer (GC) highlight the need for effective systemic neoadjuvant treatment strategies to improve clinical results. Neoadjuvant multimodality strategies vary widely. This study compared the efficacy, safety, and clinical outcomes of neoadjuvant CCRT and chemotherapy for such patients. MATERIALS AND METHODS: Sixty-five patients with histologically confirmed locally advanced or metastatic GC following neoadjuvant CCRT or computed tomography (CT) were retrospectively enrolled between January 2010 and April 2019. Clinical outcomes included response, progression-free survival (PFS), and overall survival (OS), and toxicity was compared between the two groups. RESULTS: Of the 65 patients, 18 (27.7%) were in the response group (2 patients with a complete response and 16 with a partial response) and 47 (72.3%) in the nonresponse group (29 patients with a stable disease and 18 with a progressive disease). Multivariate analysis revealed no independent response predictor between CCRT and chemotherapy groups (all P > 0.05). Furthermore, results revealed no statistical differences in toxicity between the two groups (all P > 0.05). With a follow-up median of 12 months (ranging 6–48 months), 12-month OS and PFS were 39.7% and 20.4% in the CCRT group and 30.3% and 13.2% in the chemotherapy group, respectively. The median OS and PFS were 14.0 months (95% CI 9.661–18.339) and 9.0 months (95% CI 6.805–11.195) in the CCRT group and 10.0 months (95% CI 6.523–13.477) and 8.0 months (95% CI 6.927–9.073) in the chemotherapy group, respectively. Both OS (P=0.011) and PFS (P=0.008) in patients with CCRT were significantly better than those in patients with chemotherapy alone. CONCLUSION: Neoadjuvant CCRT achieved more favorable OS and PFS than did neoadjuvant chemotherapy alone, without significant increases of toxicity in patients. However, prospective randomized trials comparing treatment modalities are necessary to confirm the potential advantages of neoadjuvant CCRT.