A Case-control Study On The Associations Between Polymorphism Of GSTM1, GSTT1 And Susceptibility To Breast Cancer And Lung Cancer

Objectives: To explore the effect of GSTM1, GSTT1 deletion and some other risk factors, and gene-environment interactions in the procession of breast cancer and lung cancer.Methods: A case-control study was conducted. 104 breast cancer cases and 152 normal women as a control, 42 lung cancer cases and 103 normal controls were recruited in the study. Breast cancer cases were collected from Feb. 2004 to Sep. 2004, while lung cancer cases from Jan. 2004 to Jan. 2006. Controls were selected from the health examination clinics. Individuals showing any evidence of cancer, suspicious precancerous lesions of cancer, and women with reproductive system disease or endocrine system disease were excluded. Several experienced postgraduates were assigned to administrate a questionnaire to both cases and control subjects in face-to-face interview. A multiplex PCR assay was used to determine the deletion polymorphism in GSTM1 and GSTT1. Unconditional logistic regression and multivariate logistic regression were used to analyze the effect of the collected factors. Multifactor dimensionality reduction (MDR) was used to analyze gene-gene and gene-environment interactions.Results:①Results from univariate logistic regression showed that the following factors were significantly associated with breast cancer: BMI, abortion (≥3), no breast-feeding, cigarette smoking, and high intakes of eggs, milk, vegetables, fruits and intake of salted or smoked meat No breast-feeding, high intakes of eggs, milk, fruits, animal oil and intake of salted or smoked meat were significantly associated with post-menopause breast cancer. Abortion (≥3), no breast-feeding, smoking, high intakes of eggs, milk, fruits, vegetable oil, and intake of salted or smoked meat were significant associated with pre-menopause breast cancer. Results from univariate logistic regression showed that smoking, alcohol drinking and chronic bronchitis were significantly associated with lung cancer. Lung cancer risk rose significantly with higher accumulative cigarette consumption (≥30pack-years).②The results of multivariate logistic regression showed that abortion (≥3), smoking, intake of salted or smoked meat were risk factors for breast cancer, with OR (95%): 3.180(1.020～9.913), 38.367(3.480～422.969), 2.543(1.074～6.024) respectively. High intakes of soybeans, milk, fruits were protective factors for breast cancer, with OR (95%CI): 0.356(0.168～0.752), 0.205(0.077～0.543), 0.420(0.198～0.889) respectively. High accumulative cigarette consumption(≥30pack-years) was risk factor for lung cancer, with OR～5.720, 95%CI: 1.462～22.241, adjusted by alcohol drinking and chronic bronchitis.③GSTM1, GSTT1 deletion or combination of the two genes were not significantly different between breast cancer cases and controls, while GSTT1 deletion was associated with breast cancer in post-menopause women. GSTM1, GSTT1 deletion or combination of the two genes were not significantly different between lung cancer cases and controls.④The best model was found for interactions among GSTM1, GSTT1, smoking, and intake of salted or smoked meat through MDR.Conclusions: abortion(≥3), smoking, intake of salted or smoked meat were risk factors for breast cancer, while high intakes of soybeans, milk, fruits were protective factors for breast cancer. Lung cancer risk rose significantly with higher cumulative cigarette consumption confirming the association with smokmg-related lung cancer risk. GSTM1 null genotype increases breast cancer risk in post-menopause women.The four-factor interaction among GSTM1, GSTT1, smoking, intake of salted and smoked meat was associated with breast cancer.