[A case of type 4 gastric cancer with peritoneal dissemination complicating venous thromboembolism treated effectively by combination of S-1 and warfarin].

A 49-year-old female patient was admitted to our hospital for a type 4 gastric cancer with peritoneal dissemination. Two courses of paclitaxel (PTX), and eight courses of S-1 were carried out. Although a partial response was obtained, she had complications with a deep venous thromboembolism (DVT) and pulmonary embolism (PE) during the treatment. Heparin, followed by warfarin, was useful to treat the embolism. After the venous thromboembolism (VTE) disappeared, combination therapy with S-1 and warfarin were started, and the quality of life (QOL) of this patient was maintained for about one year. Fine monitoring of the international normalized ratio (INR) was required in order to prevent side effects of blood coagulation by S-1 and warfarin coadministration. This case suggests that the combination therapy of S-1 and warfarin may be a safe and effective treatment able to prolong time to progression against a type 4 gastric cancer with VTE.