Glutathione-S-transferase (GSTM1) genetic polymorphisms do not affect human breast cancer risk, regardless of dietary antioxidants

Glutathione-S-transferases catalyze the detoxication of carcinogen metaboli tes and reactive oxygen species (ROS) produced through a number of mechanis ms. Glutathione-S-transferase (GST) M1 is polymorphic, and the null allele results in a lack of enzyme activity. Because there are indications that RO S may be involved in breast carcinogenesis, we sought to determine whether the GSTM1 null allele was associated with increased breast cancer, particul arly among women with tower consumption of dietary sources of alpha-tocophe rol, carotenoids and ascorbic acid. in a study of diet and cancer in wester n New York, women with primary, incident, histologically confirmed breast c ancer (n = 740) and community controls (n = 810) were interviewed and an ex tensive food-frequency questionnaire administered. A subset of these women provided a blood specimen. DNA was extracted and genotyping performed for G STM1. Data were available for 279 cases and 340 controls. The null allele d id not increase breast cancer risk, regardless of menopausal status. There were also no differences in associations between the polymorphism and risk among lower and higher consumers of dietary sources of antioxidants or smok ers and nonsmokers. These results indicate that GSTM1 genetic polymorphisms are not associated with breast cancer risk, even in an environment low in antioxidant defenses.