[5-FU concentration in tumor tissue and the antitumor effect in patients with gastric cancer after oral administration of UFT].

Serum and tumor tissue concentration of FT, 5-FU and uracil were measured in 23 patients with gastric cancer who were administered UFT preoperatively. The degeneration of cancer cells was evaluated histologically and the correlation between 5-FU concentration in the tumor tissue and the antitumor effect was assessed. The average concentration of 5-FU in tumor tissue (0.122 microgram/g) was significantly higher than that in normal gastric tissues. Serum 5-FU concentration was very low, suggesting no accumulation of 5-FU in blood. A positive correlation between the concentration of 5-FU and uracil in tumor tissues was found. A 5-FU level higher than 0.05 microgram/g was frequently demonstrated in tumor tissue, resulting in moderate degeneration of cancer cells in many cases. When tumors were classified according to histological type, intratumoral 5-FU concentration was not always correlated with degeneration of cancer cells. The above results suggested that UFT was a very effective drug for stomach cancer because of high tumor affinity for 5-FU, but that it is necessary to consider the sensitivity of tumor cells to antitumor drugs in order to obtain an excellent antitumor effect.