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

Purpose: Hyperbaric oxygen (HBO) has been shown to increase tumor radiosens itivity. Several reports indicate that it also increases sensitivity to alk ylating agents, but other reports suggest that it may speed angiogenesis an d tumor growth. To throw light on these questions, we investigated the effe cts of HBO and 5-fluorouracil (5-FU), individually and in combination, on S arcoma 180 implants in mice. Methods: We administered 5-FU at a dose of 0.7 5 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 treatm ent period, tumor diameter increased 277.8% in the untreated control group, 244.1% in the group receiving HBO monotherapy, 182.7% in the group receivi ng 5-FU monotherapy, and 138.5% in the group receiving combination therapy. Concomitant HBO increased accumulation of 5-FU in the tumors, liver, and k idneys, but not in the brain, of recipient animals. Conclusions: Based on t he above results, we conclude that concomitant HBO enhances the effects of 5-FU.