[Two patients effectively treated by S-1 monotherapy for metastatic pancreatic cancer].

We report two metastatic pancreatic cancer patients who showed marked tumor shrinkage following administration of the oral fluorinated pyrimidine anticancer drug, S-1. In the early phase II trial of S-1 for metastatic pancreatic cancer, both patients showed a partial response (Japan Society for Cancer Therapy Criteria): the reduction ratio of the tumor volume was 81.4% in the patient with liver metastasis (Case 1) and 86.9% in the patient with lung metastasis (Case 2). Case 1 showed grade 3 anorexia and decrease of the serum hemoglobin as severe adverse effects, but the other adverse reactions were mild. Both patients could be treated as outpatients. S-1 showed a promising antitumor effect and tolerability in patients with metastatic pancreatic cancer, and it was also considered to be beneficial for patients in terms of convenience of administration, that is, by the oral route.