Nonalcoholic fatty liver disease is associated with breast cancer in nonobese women

Background Growing evidence supports that nonalcoholic fatty liver disease (NAFLD) is associated with extrahepatic cancers. Nonalcoholic fatty liver disease (NAFLD) and breast cancer share similar risk factors, including obesity. Aim The aim of this case-control study was to investigate the association between NAFLD and breast cancer. Methods Subjects who received health screening, including mammography and breast and hepatic ultrasonography simultaneously, were included. Subjects diagnosed with breast cancer were matched with controls. Conditional logistic regression analyses were performed. Results Among 270 breast cancer patients and 270 controls, 81 cancer patients (30.0%) and 54 controls (20.0%) had NAFLD (P = 0.008). NAFLD was significantly associated with breast cancer in multivariate analysis (P = 0.046). When the interaction between obesity (BMI < 25 kg/m2 vs. ≥25 kg/m2) and NAFLD in breast cancer patients was examined, a significant effect modification between obesity and NAFLD in breast cancer was noted (P = 0.021). The subgroup analysis showed that NAFLD was significantly associated with breast cancer in the nonobese subgroup (odds ratio 3.04, 95% confidence interval 1.37–4.32, P = 0.002) but not in the obese group (P = 0.163). Conclusions NAFLD was significantly associated with breast cancer independent of traditional risk factors, and this association existed in the nonobese subgroup but not in the obese subgroup.