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.

Anai H, Sakaguchi Y, Emi Y, Kohnoe S, Maehara Y, Sugimachi K.

Cancer Center, Kyushu University Hospital, Fukuoka, Japan.

Abstract

Effects of the 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 micrograms/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 micrograms.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.