Metabolic syndrome and the risk of breast cancer among postmenopausal women in North-West China.

Objective: To determine whether metabolic syndrome (MetS) and its components are risk factors for breast cancer among postmenopausal women in China.
Methods: Based on the baseline data of the Jinchang Cohort, a case-control study was carried out among postmenopausal women, including 43 cases and 86 controls. Both MetS and its components were evaluated. Odds ratios and 95% confidence intervals (CI) for the association were estimated by conditional logistic regression analysis.
Results: The odds ratio of postmenopausal breast cancer was 3.505 (95% CI 1.282-9.583) for MetS, 3.016 (95% CI 1.044-8.715) for body mass index (BMI) ≥ 25 kg/m(2), and 3.191 (95% CI 1.253-8.125) for dyslipidemia. There was no significant association between postmenopausal breast cancer and hypertension as well as diabetes. Women with four metabolic factors showed greater risk for postmenopausal breast cancer (p(trend) < 0.05). Dyslipidemia and BMI ≥ 25 kg/m(2) showed most significant interaction on breast cancer (odds ratio = 11.359; 95% CI 2.663-48.450). With BMI ≥ 25 kg/m(2), the interaction of dyslipidemia and other metabolic factors on breast cancer was higher than that without BMI ≥ 25 kg/m(2).
Conclusion: This case-control study suggested that MetS was associated with an elevated risk of breast cancer among postmenopausal women in north-west China. Overweight and dyslipidemia had the strongest adverse effects on postmenopausal breast cancer.