Use of 5-FU plus hyperbaric oxygen for treating malignant tumors: evaluation of antitumor effect and measurement of 5-FU in individual organs

Abstract

Purpose: Hyperbaric oxygen (HBO) has been shown to increase tumor radiosensitivity. Several reports indicate that it also increases sensitivity to alkylating agents, but other reports suggest that it may speed angiogenesis and tumor growth. To throw light on these questions, we investigated the effects of HBO and 5-fluorouracil (5-FU), individually and in combination, on Sarcoma 180 implants in mice. Methods: We administered 5-FU at a dose of 0.75 mg/mouse six times per week and HBO at 2 atm absolute pressure for 90 min six times per week, both 17 times in total. In combination treatment, HBO was administered immediately after 5-FU injection. Results: Over the treatment period, tumor diameter increased 277.8% in the untreated control group, 244.1% in the group receiving HBO monotherapy, 182.7% in the group receiving 5-FU monotherapy, and 138.5% in the group receiving combination therapy. Concomitant HBO increased accumulation of 5-FU in the tumors, liver, and kidneys, but not in the brain, of recipient animals. Conclusions: Based on the above results, we conclude that concomitant HBO enhances the effects of 5-FU.