Phase II clinical trial to study the safety and efficacy of combined S-1 + oxaliplatin therapy as neoadjuvant chemotherapy for locally advanced gastric cancer in older patients.

Background: Gastrectomy with D2 dissection and adjuvant chemotherapy is the standard treatment for locally advanced gastric cancer (LAGC) in Asia. However, administering chemotherapy with sufficient intensity after gastrectomy is challenging. Several trials demonstrated the efficacy of neoadjuvant chemotherapy (NAC). However, limited studies explored the feasibility of NAC-SOX for older patients with LAGC. This phase II study (KSCC1801) evaluated the safety and efficacy of NAC-SOX in patients with LAGC aged ≥ 70 years.

Methods: Patients received three cycles of SOX (oxaliplatin 130 mg/m on day 1, oral S-1 40-60 mg twice daily for two weeks every three weeks) as NAC, followed by gastrectomy with lymph node dissection. The primary endpoint was the dose intensity (DI). The secondary endpoints were safety, R0 resection rate, pathological response rate (pRR), overall survival, and relapse-free survival.

Results: The median age of 26 enrolled patients was 74.5 years. The median DI in NAC-SOX was 97.2% for S-1 and 98.3% for oxaliplatin. Three cycles of NAC were administered in 25 patients (96.2%), of whom 24 (92.3%) underwent gastrectomy with lymphadenectomy. The R0 resection rate was 92.3% and the pRR (≥ grade 1b) was 62.5%. The major adverse events (≥ grade 3) were neutropenia (20.0%), thrombocytopenia (11.5%), anorexia (11.5%), nausea (7.7%), and hyponatremia (7.7%). Postoperative complications of abdominal infection, elevated blood amylase, and bacteremia occurred in one patient each. Severe diarrhea and dehydration caused one treatment-related death.

Conclusions: NAC-SOX is a feasible therapy for older patients, although systemic management and careful monitoring of adverse events are necessary.