DNA repair capacity measured by high throughput alkaline comet assays in EBV-transformed cell lines and peripheral blood cells from cancer patients and healthy volunteers

We collected peripheral blood (PB) from 556 patients with various types of cancer who had undergone radiotherapy and from 81 healthy volunteers. We exposed whole PB and Epstein-Barr virus-transformed lymphoblastoid cell lines (EBLs) derived from the PB mononucleocytes to X-irradiation (5 Gy). Using the alkaline comet assay, we measured the immediate DNA damage and, at 15 min, the % residual damage. In PB, the immediate damage was similar in patients and healthy volunteers while the % residual damage (mean ± S.D.) was significantly higher in patients with breast (54.3 ± A23.9), cervical (54.7 ± A23.9), head/neck (56.8 ± A24.4), lung (60.1 ± 23.5), or esophageal cancers (59.5 ± A33.7) than in healthy donors (42.9 ± 19.6) (P < 0.05). We did not observe such differences in the EBV-transformed cell lines. Thus, radiation sensitivity of fresh PB cells measured by the alkaline comet assay was related to cancer status.