Intake of total cruciferous vegetable and its contents of glucosinolates and isothiocyanates, GST polymorphisms, and breast cancer risk: a case-control study in China.

Cruciferous vegetables contained high levels of glucosinolates (GSL) and isothiocyanates (ITC). ITC is known to induce glutathione S-transferases (GSTs) thus exert its anticarcinogenic effects. This study explored the combined effects of cruciferous vegetables, GSL, ITC intake and GST polymorphisms on breast cancer risk. A total of 737 breast cancer cases and 756 controls were recruited into this case-control study. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were assessed by multivariable logistic regression. Higher cruciferous vegetables, GSL and ITC intake was inversely associated with breast cancer risk, with adjusted ORs (95% CIs) of 0.48 (0.35, 0.65), 0.54 (0.40, 0.74) and 0.62 (0.45, 0.84), respectively. Compared with women carrying GSTP1 rs1695 wild AA genotype and high cruciferous vegetables, GSL or ITC intake, carriers of AA genotype with low cruciferous vegetables, GSL and ITC intake had greater risk of breast cancer, with adjusted ORs (95% CIs) of 1.43 (1.01, 1.87), 1.34 (1.02, 1.75) and 1.37 (1.05, 1.80), respectively. Persons with GSTM1 null genotype and lower intake of cruciferous vegetables, GSL and ITC had higher risk of breast cancer than those with GSTM1 present genotype and higher intake, with ORs (95% CIs) of 1.42 (1.04,1.95), 1.43 (1.05,1.96) and 1.45 (1.06,1.98), respectively. Among women possessing GSTT1 present genotype, low intake of cruciferous vegetables, GSL or ITC was associated with higher risk of breast cancer. But these interactions were non-significant. This study indicated that there were no significant interactions between cruciferous vegetables, GSL or ITC intake and GST polymorphisms on breast cancer risk.