Primary results of a randomized two‐by‐two factorial phase II trial comparing neoadjuvant chemotherapy with two and four courses of cisplatin/S‐1 and docetaxel/cisplatin/S‐1 as neoadjuvant chemotherapy for advanced gastric cancer

Aim Neoadjuvant chemotherapy (NAC) is promising to improve the survival of resectable gastric cancer. However, suitable regimen and treatment duration for NAC have not yet been established. Methods We conducted a randomized phase II trial to compare two and four courses of neoadjuvant S‐1/cisplatin (SC) and S‐1/cisplatin/docetaxel(DCS) using a two‐by‐two factorial design for locally resectable advanced gastric cancer. Patients with M0 and either T4 or T3 in case of junctional cancer or scirrhous‐type cancer received two or four courses of SC or DCS. Then, patients underwent D2 gastrectomy and adjuvant S‐1 chemotherapy for 1 year. The primary endpoint was 3‐year overall survival. The planned sample size was 120 eligible patients. Results Between October 2011 and September 2014, 132 patients were assigned to CS (n = 66; 33 in 2‐courses and 33 in 4‐courses) and DCS (n = 66; 33 in 2‐courses and 33 in 4‐courses). The 3‐year OS was 58.1% in CS and 60.0% in DCS with hazard ratio of 0.80 (95% CI, 0.48‐1.34), while it was 53.1% in the two courses and 65.0% in the four courses with hazard ratio of 0.72 (95% CI, 0.43‐1.22). In the survival analysis by duration in each regimen, the 3‐year OS was 58.1% for both two and four courses in CS, while it was 48.5% for two courses of DCS and 71.9% for four courses of DCS. Conclusions Considering high 3‐year OS, four courses DCS has a value to be tested in a future phase III study to confirm superiority of neoadjuvant chemotherapy for locally advanced gastric cancer. Overall survival curves stratified by regimens, number of courses.