Bleomycin-induced mutagen sensitivity, passive smoking, and risk of breast cancer in Chinese women: a caseâ[euro]"control study

It is well recognized that genetic variation as well as environmental factors modulates breast cancer risk. Deficiencies in DNA repair capacity are thought to associate with breast cancer risk. The main aim of this study was to use the mutagen sensitivity assay as an indirect measure of DNA repair capacity to assess breast cancer risk and the relationship between passive smoking and breast cancer risk among women in China. We carried out a caseâ[euro]"control study, involving 196 Chinese patients with breast cancer and 211 controls without the disease and with no history of cancer. We investigated the association between mutagen sensitivity and breast cancer risk using bleomycin as the mutagen. Mutagen sensitivity was measured by quantifying the chromatid breaks induced by mutagens in short-term cultures of peripheral blood lymphocytes. Nonparametric tests and the Fisherâ[euro](TM)s exact test were used to determine the statistical significance of the crude caseâ[euro]"control comparisons, followed by logistic regression to adjust for important covariates. The mean number of bleomycin-induced breaks per cell was 0.81 for cases compared with 0.73 for the controls (p = 0.016). A greater number of bleomycin-induced chromosomal breaks per cell was associated with an increased risk of breast cancer (adjusted odds ratio of 1.82, p trend