Synergistic effect of methotrexate and radiation on gliosarcoma in tissue culture and in rats.

In vitro and in vivo studies were performed on rat gliosarcoma cells (RT-9) to investigate the synergistic effect of methotrexate and radiation against malignant brain tumors. For in vitro study, RT-9 cells were cultured on microtiter plates and treated with methotrexate, radiation, or both. For in vivo study, the cells were implanted into the cerebrums of CD-Fischer rats, and intraperitoneal methotrexate, whole brain radiation, or both were given. Although synergistic suppression of cell growth with combined therapy was observed in the in vitro study, synergism was less clearly demonstrated in tumor-bearing rats because of systemic toxicity of the therapy.