Histone γ-H2AX foci in PBMCs derived from normally-reacting and radiosensitive BC patients compared with control donors. DNA damage assessed by means of the histone γ-H2AX assay in non-irradiated (A) and irradiated (B-D) PBMCs derived from normally-reacting BC patients (up triangles) and radiation-sensitive (down triangles) cancer patients compared to cells from apparently healthy donors (circles). Initial (B), residual DNA damage 24 h after in vitro 2 Gy (C) or 72 h after 5 clinical radiation fractions (D) were assessed in PBMCs after irradiation with in vitro (B, C) or in vivo (D). Filled squares represent the mean values (± SD) for the respective group. “n.s.” indicates that the difference was not highly significant (p > 0.05).