Radiobiological Response of Cervical Cancer Cell Line in Low Dose Region: Evidence of Low Dose Hypersensitivity (HRS) and Induced Radioresistance (IRR).

BACKGROUND: Purpose of the present study was to examine the response of cervical cancer cell line (HeLa cell line) to low dose radiation using clonogenic assay and mathematical modeling of the low dose response by Joiner's induced repair model. MATERIALS AND METHODS: Survival of HeLa cells following exposure to single and fractionated low doses of γ (gamma)-ray, 6 MV, and 15 MV photon was measured by clonogenic assay. RESULTS: HeLa cell line demonstrated marked low dose response consisting of an area of HRS and IRR in the dose region of <1 Gy. The two gradients of the low dose region (αs and αr) were distinctly different with a transition dose (Dc) of 0.28-0.40 cGy. CONCLUSION: HeLa cell line demonstrates marked HRS and IRR with distinct transition dose. This may form the biological basis of the clinical study to investigate the chemo potentiating effect of low dose radiation in cervical cancer.