Long-term results of a phase II study of two courses of neoadjuvant chemotherapy with S-1 plus oxaliplatin for cT4 or N2-3 gastric cancer

Abstract Purpose To evaluate the long-term survival outcomes from our previous study: the phase II study of neoadjuvant chemotherapy with S-1 plus oxaliplatin for cT4 or N2-3 advanced gastric cancer. Methods The patients with clinical T4 and/or N2 or more lymph nodes received two cycles of neoadjuvant chemotherapy with S-1 plus oxaliplatin (oxaliplatin at 130 mg/m 2 on day 1 and S-1 at 80–120 mg/day for 2 weeks, q 3 weeks), followed by gastrectomy with D2 lymphadenectomy. The final preplanned analysis of long-term outcomes, including overall and relapse-free survival, was performed. This trial has been completed and registered with the University Hospital Medical Information Network Clinical Trials Registry under number UMIN 000024656. Results Between May 2016 and March 2019, 30 patients were enrolled. All patients could complete the protocol. After a median follow-up of 50 months for surviving patients, the 3-year overall and recurrence-free survival rates were 80.0% and 76.7%, respectively, at the last follow-up in March 2023, whereas the 5-year overall and recurrence-free survival rates were 72.7% and 73.0%, respectively. Conclusion Two cycles of neoadjuvant chemotherapy with S-1 plus oxaliplatin, followed by D2 gastrectomy, was associated with relatively good long-term oncologic outcomes for patients with high-risk gastric cancer.