[A case of advanced gastric cancer showing high serum CYFRA21-1 level responding to chemotherapy with S-1].

The patient was a 75-year-old man whose complaint was back pain and appetite loss. He was diagnosed with unresectable advanced gastric cancer due to multiple liver metastases and direct invasion of pancreas and spleen. He underwent gastrostomy because of esophageal stenosis, and we administered S-1 80 mg/body(4 weeks administration and 2 weeks rest)to the patient through a gastrostogavage tube. On blood examination, the serum level of CYFRA21- 1 was significantly high, while those of CEA and CA19-9 were within normal ranges. After the first course of this chemotherapy, the serum CYFRA21-1 level significantly decreased with reduction of the cancer. After the second course, it sensitively increased before image views detected the progression of the cancer. This case shows that CYFRA21- 1 could be a useful tumor marker of advanced gastric cancer.