Severe normal tissue complication correlates with increased in vitro fibroblast radiosensitivity in radical prostate radiotherapy: A case report

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