Cytotoxicities of mitomycin C and x rays to aerobic and hypoxic cells in vitro.

Aerobic and hypoxic EMT6 mouse mammary tumor cels in exponential growth in vitro were used to study cell survival after treatment with radiation (250kV X rays) and mitomycin C in various combinations. The cytotoxicities of the two agents were found to be additive as judged by comparing dose-response curves for each agent alone with survival curves after combination therapy and by isobologram analysis. The cytotoxicities resulting from combination treatments were found to be independent of the sequence of the treatments or the interval between treatments.