The sensitivity of radiation and its combined effect with anticancer drugs on cultured human lung cancer cells

The cultured lung tumor cells were irradiated with 60Co γ-rays, with and without combinations of adriamycin (ADR) and 5-Fluorouracil (5-FU). Cell survival was assayed by colony formation in vitro in soft agar and in plate. Most of small cell lung carcinoma cells used here were radiosensitive, while one of them showed radioresistent comparable to non-small cell lung tumors and other tumor cells. In the treatment with drugs (ADR or 5-FJ) following 60Co γ-irradiation (postirradiation treatment), it proved to be twice as effective as drug treatment preceding irradiation (preirradiation treatment). Preirradiation treatment demonstrated that 5-FU treated cell were more radiosensitive than ADR treated ones. In the preirradiation treatment, the most enhanced killing effect was observed when cells were irradiated twenty four hours after 5-FU treatment, on the other hand, in the ADR treatment, treatment interval showed no differrece. In the postirradiation treatment, the greatest enhancement was observed when cells were irradiated twenty hours after ADR exposure, while most effective forty eight hours after 5-FU treatment. (author)