Phase II study of S-1 plus docetaxel as first-line treatment for older patients with advanced gastric cancer (OGSG 0902)

Although there is insufficient evidence for the treatment of older patients with advanced gastric cancer, fluorouracil combined with platinum chemotherapy has been recognized as a standard first-line treatment for such populations in Japan despite the lack of efficacy and toxicity data.

Patients aged 75 years or older with advanced gastric cancer were enrolled. S-1 plus docetaxel (docetaxel: 40 mg/m², day 1; S-1: 80 mg/m², days 1–14; q21 days) was repeated every 3 weeks. The primary endpoint was overall response rate. Secondary endpoints were safety, progression-free survival, time to treatment failure, and overall survival. The sample size was calculated as 30 under the hypothesis of an expected response rate of 40% and a threshold response rate of 20%, at a power of 90% and a two-sided alpha value of 5%.

From February 2010 to January 2015, 31 patients were enrolled and assessed for efficacy and toxicity. The response rate was 45.2% (95% CI 27.3%–64.0%; p = 0.001) and it exceeded the expected response rate set at 40%. Median progression-free survival was 5.8 months, the 1-year survival rate was 58.1%, and the median survival time was 16.1 months. The major grade 3/4 adverse events were neutropenia (58%), febrile neutropenia (13%), anemia (10%), anorexia (10%), and fatigue (6%).

These findings indicate that S-1 plus docetaxel as first-line treatment for older patients is feasible and that it has promising efficacy against advanced gastric cancer.