[Two cases of stage IV gastric cancer responding to chemotherapy with S-1 or UFT].

We report patients with advanced Stage IV gastric cancer responding to chemotherapy with S-1 or UFT. Case 1: The patient was a 59-year-old man with Stage IV gastric cancer because of CY 1. After surgery, chemotherapy with S-1 (100 mg/body/day) was performed for one year and 11 months.

Multidrug-resistance gene (mdr1) expression in human tumor xenografts.

We examined the expression of human multidrug resistance gene (MDR1); 13 of 34 xenografts showed various MDR1 gene transcript levels by reverse transcriptase-polymerase chain reaction. MDR1 was detected in 3 of 10 lung, 5 of 8 gastric, 3 of 3 colon and 2 of 3 pancreatic cancers, but not in 4 breast cancers, or 6 gliomas. We evaluated drug-sensitivity of xenografts in vivo; 28 of 34 xenografts showed drug resistance to vincristine and/or doxorubicin, whereas 13 of 28 drug-resistant xenografts expressed MDR1.