A PROTEIN-BOUND POLYSACCHARIDE IMMUNOMODULATOR, PSK, DOES NOT SUPPRESS THE CONVERSION FROM 1-(2-TETRAHYDROFURYL)-5-FLUOROURACIL TO 5-FLUOROURACIL IN PATIENTS WITH GASTRIC-CANCER

Effects of immunomodulator PSK on the metabolism of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) to 5-fluorouracil (5-FU) were examined in 10 patients with advanced gastric cancer and who had undergone curative resection. PSK is a protein-bound preparation, extracted from Coriolus versicolor and belongs to Basidiomycetes. The 5-FU concentration in the plasma was 0.024-mu-g/ml at 15 min after the intravenous injection of 400 mg of tegafur and the area under the curve of 5-FU was 0.58-mu-g.h/ml. Following administration of PSK, 3 g/day for 8-14 months, there was no change in the plasma level of 5-FU, in any patient. As the clinical dose of PSK had no apparent influence on the metabolism of tegafur to 5-FU, the combination of PSK and tegafur can be prescribed to treat patients with advanced gastric cancer.