Severe normal tissue complication correlates with increased in vitro fibroblast radiosensitivity in radical prostate...

The radiation responses of fibroblasts taken from four patients undergoing radiotherapy for prostate cancer were evaluated in vitro. One patient exhibited a severe normal tissue late reaction after radiotherapy, and the fibroblasts from this patient also showed increased radiosensitivity. The other three patients exhibited a normal clinical response, and their fibroblast response in vitro was also considered normal when compared with previously published data from our laboratory. When cells were allowed to repair potentially lethal damage (PLDR), the differences between cell lines were reduced; therefore, a deficiency in PLDR did not cause the differences in radiosensitivity. Fractionated radiation resulted in elevated survival due to repair of sublethal damage (SLDR), and the differences in radiosensitivity were increased. In addition, the survival curves displayed an upward bending nature, indicative of an adaptive response. Thus, adaptive response and ability to modify it may play an important role in fractionated radiotherapy. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 336-342 (2000).