The intratumoral levels of thymidylate synthetase and folate in gastric and colon cancer

: Currently, biochemical modulation for 5-fluorouracil (5-FU) is one of the most successful chemotherapy for both colo-rectal and gastric cancer. The purpose of this study is to evaluate the significance of measuring intratumoral thymidylate synthetase (TS) and folate (FH4) levels as predictive parameters for the successful treatment. Samples were collected from 16 advanced colo-rectal and 21 advanced gastric cancer. TS and tetrahydrofolate levels in the specimens were measured by binding assay. Results showed that there were no significant difference in TS levels between the different pathologic types of carcinoma. On the other hand, well (3.94 +/- 1.75 p mol/g) and moderately (5.95 +/- 2.69 p mol/g) differentiated carcinoma showed lower FH4 levels compared to poorly differentiated carcinoma (9.58 +/- 5.27 p mol/g). In conclusion, biochemical modulation by cisplatin or leucovorin, which elevates intratumoral folate levels, is more needed for well and moderately differentiated carcinoma. Finally, measuring TS levels can also be important because two cases who responded to cisplatin/5-FU chemotherapy showed low TS levels compared to the others who had lower response.