Department of Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Anticancer Res. 2011 Apr;31(4):1125-30.
This study evaluates a predictive radiobiology model by measurements of surviving fraction (SF) by the clonogenic assay or the extrapolation method and the proliferation rate in vitro. It is hypothesized that incorporating proliferation to intrinsic radiosensitivity, measured by SF, to predict radiation responsiveness after fractionated irradiation adds to the model's accuracy. Materials and Methods. Five lung cancer cell lines with known SF after 1 Gy (SF1), and also SF2 and SF5, were irradiated with three different fractionation regimes; 10 × 1 Gy, 5 × 2 Gy or 2 × 5 Gy during the same total time to achieve empirical SF. In addition, the SF1, SF2 and SF5 after fractionated irradiation was calculated for each cell line based on the already known single fraction SF and with or without a proliferation factor. The results were compared to the empirical data.
By using the clonogenic assay to measure radiosensitivity, prediction of radiosensitivity was improved after fractionated radiotherapy when proliferation was used in the radiobiology model. However, this was not the case in the cell lines where the extrapolation method was used to calculate SF. Thus, a radiobiology model including intrinsic radiosensitivity, measured by the clonogenic assay, as well as proliferation, is better at predicting survival after fractionated radiotherapy, compared to the use of intrinsic radiosensitivity alone.
本研究通过集落形成测定法或外推法测量存活分数 (SF) 和体外增殖率来评估预测放射生物学模型。假设将增殖纳入固有放射敏感性（通过 SF 测量）以预测分割照射后的辐射反应性，可提高模型的准确性。材料与方法。五种肺癌细胞系具有已知的 1 Gy 后 SF1，以及 SF2 和 SF5，采用三种不同的分割方案进行照射：10×1 Gy、5×2 Gy 或 2×5 Gy，总时间相同以达到经验 SF。此外，根据已知的单次分割 SF 并结合或不结合增殖因子，计算每个细胞系的分割照射后 SF1、SF2 和 SF5。将结果与经验数据进行比较。
通过集落形成测定法测量放射敏感性，当在放射生物学模型中使用增殖时，分割放疗后的放射敏感性预测得到改善。然而，在使用外推法计算 SF 的细胞系中并非如此。因此，与仅使用固有放射敏感性相比，包括通过集落形成测定法测量的固有放射敏感性以及增殖的放射生物学模型更能预测分割放疗后的存活。
