S-1 and Irinotecan in Treating Patients Who Are Undergoing Surgery for Locally Advanced Stomach Cancer

RATIONALE: Drugs used in chemotherapy, such as S-1 and irinotecan, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. Giving chemotherapy before surgery may shrink the tumor so that it can be completely removed. PURPOSE: This phase II trial is studying how well giving S-1 together with irinotecan works in treating patients who are undergoing surgery for locally advanced stomach cancer.