The radiosensitivities of 4 human tumor cell lines to p (35) Be neutron irradiation

Objective: The difference of radiosensitivity of 4 human tumor cell lines to p(35)Be fast neutron and gamma ray was studied in order to provide basis for clinical therapy of tumors. Methods: The radiosensitivity of these cell lines after p(35)Be neutron or gamma ray irradiation was assayed with cell clonogenic survival assay. And the gamma ray-and p(35)Be neutron-induced DNA damage and its repair in human melanoma cells line WM9839 was studied by using the method of comet-electrophoresis assay. Results: The difference of D0(or SF2) after p(35)Be neutron irradiation between these 4 human tumor cell lines was smaller than that after gamma ray irradiation. The repair rate of DNA damage in WM9839 cells after 2 Gy fast-neutron irradiation was lower than that after 2 Gy γ-ray irradiation. The residual DNA damage at 180 min after neutron-irradiation was obviously severer than that after 2 Gy γ-ray irradiation. Conclusion: The fast neutron therapy may make up the defect of the low LET ray therapy, especially to those radioresistant tumor cells to low LET rays