A predictive factor for the response to S-1 plus cisplatin in gastric cancer

AIM:To prove that the protein expression level of thymidylate synthase is a predictive factor for the response to S-1/cisplatin(CDDP)chemotherapy in gastric cancer.METHODS:We measured the protein expression levels of thymidylate synthase(TS),dihydropyrimidine dehydrogenase(DPD),and orotate phosphoribosyltrans-ferase(OPRT)in advanced gastric cancer.Before S-1/CDDP chemotherapy,tumor specimens from primary sites were obtained by endoscopic biopsy and analyzed by enzyme-linked immunosorbent assay.The chemo-therapeutic effects on the primary sites were evaluated by endoscopic biopsy performed more than once after S-1/CDDP chemotherapy.The effects are a predictive factor for the response to S-1/CDDP chemotherapy inpatients with advanced gastric cancer,as evaluated by endoscopic biopsy over time.RESULTS:The protein expression level of TS was significantly higher(P 40 ng/mg protein.CONCLUSION:We have confirmed that the protein expression level of TS is a predictive factor for the response to S-1/CDDP chemotherapy in patients with advanced gastric cancer.