[Changes in folate levels after cisplatin treatment of gastric cancer]

Currently, biochemical modulation for 5-fluorouracil (5-FU) by cisplatin (CDDP) is one of the most successful forms of chemotherapy for gastric cancer. Although the mechanism of this modulation is thought to increase intracellular folate levels, it is still unknown how much CDDP is needed to elevate folate levels. The purpose of this study is to determine the appropriate volume of CDDP as a modulator for 5-FU. Either 5, 20, 100 mg/body of CDDP was administered intravenously to advanced gastric cancer patients just before operation. Four hrs later, the stomach was resected and folate levels were measured in the tumor and normal mucosa by thymidylate synthase binding assay. The results showed folate elevation only after administration of 100 mg/body of CDDP, both in the tumor and mucosa (p < 0.01). In conclusion, if CDDP is infused as a bolus, a relatively large amount is needed to modulate the intratumor folate level.