Trial Information

Feasibility Trial of Neoadjuvant Chemoradiotherapy in Patients With Locally Advanced Gastric Cancer Combined With Adjacent Tissue Invasion

Since S-1 (combined drug of tegafur, 5-chloro-2,4-dihydroxypyridine and potassium oxonate)
was approved in Japan in 1999 after a large-scale clinical trial, adjuvant chemotherapy with
S-1 has been the standard treatment for stage II/III gastric cancer. However, for
far-advanced gastric cancer, various adjuvant chemotherapies, including S-1, have not
achieved satisfactory results. Therefore, Japan Clinical Oncology Group (JCOG) is currently
performing phase 2 and 3 clinical trials of neoadjuvant chemotherapy (NAC) for locally
far-advanced gastric cancer. However, previous studies of NAC have reported a pathological
response rate of 15-50% for the main lesion, indicating no significant effect on local tumor
control.

On the other hand, other studies have reported that anticancer drugs, including S-1, have a
radiosensitizing effect, and that neoadjuvant chemoradiotherapy (NACRT) achieves superior
local tumor control compared with NAC. Therefore, we conducted a feasibility trial of NACRT
with S-1 for locally far-advanced gastric cancer combined with adjacent tissue invasion.