Due to the frequency of febrile neutropenia or infection with neutropenia and the actual dose intensity of S-1 and docetaxel in phase II of our trial, we propose that the RD of this regimen be lowered to 35 mg m−2 b.i.d. S-1 on days 1–14 and/or 30 mg m−2 docetaxel on days 1 and 8 of each 3-week cycle, or prophylactic granulocyte colony-stimulating factor be used. This evidence concerns the gene CSF3 and neutropenia.