Potentiation of rat brain tumor therapy by fluosol and carbogen.

We have been using the 9L rat brain tumor model to investigate the effect of the combination of a perfluorochemical emulsion, Fluosol-DA 20%, and carbogen breathing on the therapy of brain tumors. The combination of Fluosol, carbogen breathing, and carmustine (BCNU) was more effective at prolonging survival than was BCNU alone. This difference was small but significant (P less than 0.25). neither Fluosol without carbogen nor carbogen without Fluosol significantly altered the effect of BCNU. Fluosol and carbogen alone did not affect the survival of tumor-burdened rats. Fluosol and carbogen breathing did not alter the effect of single doses of radiation on these tumors. This result supports the hypothesis that 9L brain tumors contain few, if any, critical hypoxic cells. However, these tumors may contain cells which are oxygen deficient but not radiobiologically hypoxic. The Fluosol-carbogen combination may be changing the intratumor environment in such a way that the metabolism or activity of BCNU is altered.