Genotoxic effect of cigarette smoking detected by comet assays using high-throughput scanning of lymphocytes

Breast cancer poses a serious public health problem, and identification of genetic and environmental factors contributing to the development of therapy-induced morbidity of breast cancer will hopefully enhance prevention of this cancer.Aim To examine the genotoxic effects of cigarette smoking on DNA damage among patients with breast cancer, we applied alkaline comet assay as a genotoxicity test in high-throughput fashion. Our aim in this study was to evaluate the utility of alkaline comet assay for determining smoking effect on acute skin reaction after radiotherapy.Materials and methods Between October 2001 and December 2003, a total of 420 female patients with breast cancer who had undergone radiotherapy after breast-conserving surgery were recruited from 5 collaborating Japanese institutions. Of these, 191 had complete clinical information, and 71 patients were recruited into alkaline comet assay. Of these, 50 patients with information about smoking habits participated in this study. A total of 70 healthy women also participated in the study. Physicians in collaborating institutions obtained medical history and clinical details for patients, including information about tumor, therapy, and adverse effects of radiation therapy from patient records. Adverse effects on skin after radiotherapy for breast-conserving surgery were clinically scored according to the common toxicity criteria system of the NIH. Alkaline comet assay measured X-ray induced DNA damage, quantified by mean tail moment as a parameter of initial damage and residual damage (RD) at 15 min after irradiation, in individual B lymphocyte cell lines established from peripheral blood. Statistical analysis was applied to evaluate alkaline comet assay as a genotoxicity test to evaluate the effects of cigarette smoking.Results:RD was significantly higher in patients with grade 2+3 than in those with grade 0+1 or in healthy controls. However, no correlation was observed between cigarette smoking and alkaline comet assay, and this approach did not reveal significant differences between smokers and non-smokers. Conclusions: Although more data are needed for a final conclusion, the obvious inconsistency in detection of smoking-related genotoxic effects indicates some limitations to comet assay with regard to detection of DNA-damage induced by environmental mutagens.The 7th International Symposium on Predictive Oncolog