Long-term Results of a Phase II Study of Neoadjuvant SOX for Advanced Gastric Cancer

This study aimed to evaluate the long-term survival outcomes from our previous study: a phase II study of neoadjuvant chemotherapy with S-1 plus oxaliplatin for cT4 or N2-3 advanced gastric cancer.

The patients with clinical T4 and/or N2 or more lymph nodes received two cycles (3 weeks per cycle) of neoadjuvant chemotherapy with S-1 plus oxaliplatin (oxaliplatin at 130 mg/m2 on day 1 and S-1 at 80-120 mg/day on days 1 to 14), 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.

Between May 2016 and March 2019, 30 patients were enrolled. All patients completed 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.

The administration of 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.