INTRODUCTION: Patients with large Stage IV gastric cancer (GC) invading the proximal stomach find it difficult to receive not only bypass surgery but also S-1-based chemotherapy. This study aimed to show our treatment results for those GC patients using elementary diet (ED) tubes, which enabled S-1-based chemotherapy and nutrition support. CASE PRESENTATION: We evaluated 20 patients (13 men and 7 women
median age 70 years) with large Stage IV GCs (8.7-21.9 cm) invading the proximal stomach, who were admitted due to inability to eat, treated with S-1-based chemotherapy using an ED tube. The duration from the initiation of the chemotherapy to the improvement of oral intake, changes in nutritional status, and disease-specific survival (DSS) were retrospectively investigated. Two of the 20 patients failed to complete even one cycle of chemotherapy due to severe nausea or diarrhea. The other 18 patients improved oral liquid intake after 47.5 ± 18.8 days, and 17 patients improved oral solid food intake after 54.5 ± 19.6 days from the start of chemotherapy. In addition, three patients (16.7%) could receive conversion surgery after improvement of oral intake. The median DSS of those 18 patients was 13.1 months. Serum albumin level and prognostic nutritional index (PNI) were significantly improved after about 1 month of the treatment (both CONCLUSIONS: Given a high oral intake success rate, S-1-based chemotherapy using an ED tube can be a promising treatment option for large Stage IV GC with poor oral intake.