Objective: To investigate the interaction of body mass index(BMI)and a single nucleotide polymorphism (SNP, rs17883901) in catalytic subunit of glutamate-cysteine ligase (GCLC) on breast cancer risk.
Methods: A total of 839 women with incident breast cancer and 863 age-matched controls without cancer were recruited at the same period in three affiliated hospitals of Sun Yat-sen University in Guangzhou from October 2008 to June 2010. GCLC rs17883901 was genotyped by MALDI-TOF-MS. Binary unconditional logistic regression was applied to calculate odds ratios and 95% confidence intervals.
Results: The difference of present BMI and BMI at age 20 was not statistically significant between cases and controls, either as the genotypes of GCLC. No association was found between BMI at present and premenopausal or postmenopausal breast cancer risk. But we found that women who had a BMI at age 20 of 18.5 to 22.9 had a marginally decreased risk of premenopausal breast cancer [OR and 95%CI:0.69(0.48, 1.00)]. Among women with CT/TT genotypes, whose present BMI was greater than 25 had a increased risk [OR and 95%CI:1.91(1.09, 3.36)] of breast cancer and a decreased risk [OR and 95%CI:0.56 (0.31,0.99)] with a BMI at age 20 of 18.5 to 22.9. There was a interaction between GCLC gene(rs17883901)and BMI at present in breast cancer risk (P = 0.043), which was not found between rs17883901 and BMI at age 20.
Conclusion: Our findings indicate BMI at age 20 may be a protective factor of premenopausal breast cancer, while no association appears between GCLC(rs17883901) and breast cancer. Obesity at present may significantly increase the risk of breast cancer among women with CT/TT genotypes of GCLC (rs17883901).