The inherent cellular radiosensitivity of epithelial ovarian carcinoma

Ovarian carcinomas of similar histology have variable responses to radiation therapy. It has been suggested that inherent cellular resistance to radiation may in part underlie radiotherapy failure. To determine in vitro radiobiological parameters of papillary serous adenocarcinoma of the ovary, we investigated the cellular responses of 16 early-passage ovarian carcinoma cell lines to radiation. The radiosensitivity, as measured by D0, ranged from 1.05 to 2.40 Gy (mean 1.70 Gy), and, as measured by D, ranged from 1.65 to 3.54 Gy (mean 2.38 Gy). The extrapolation number -n ranged from 1.1 to 2.0 (mean 1.5). The cells had a 1.3- to 5.4-fold (mean 2.8) ability to recover from potential lethal damage (PLDR) 24 hr after irradiation and subculture from plateau-phase cultures. Their inherent radioresistance may be one factor in the failure of some ovarian cancers to be sterilized by radiation.