Insulin resistance and breast carcinogenesis: a cross-sectional study among Iranian women with breast mass

Despite existing epidemiologic data concerning the increased incidence of breast cancer in diabetes type 2, the association between insulin resistance and breast carcinogenesis is not yet well defined. In this cross-sectional study, we examined the homeostatic model assessment values of insulin resistance (HOMA-IR) among 82 patients with malignant breast tumor, 48 subjects with benign breast mass, and 838 healthy Iranian women. One hundred and thirty (n = 130) surgical inpatients of Tehran Central Cancer Institute (Tehran, Iran) were evaluated preoperatively. Healthy subjects were nondiabetic, nonhypertensive women aged 20-77 years from four different locations in Tehran. Age and central obesity-adjusted HOMA-IR values were 3.6 [95% confidence interval (CI), 2.8-4.4], 2.3 (1.7-2.9), and 1.7(1.6-1.8) correspondingly in subjects with malignant breast tumor, those with benign breast mass, and healthy subjects. The interaction effect of age on the association between breast mass (malignant/ benign /no breast mass) with HOMA-IR values was significant [F(54) = 10, P < 0.001, partial eta squared = 0.03]. The interaction of central obesity on this association was also significant [F(54) = 37, P < 0.001, partial eta squared = 0.11]. We conclude that the noted linkage between insulin resistance and breast cancer may indicate an underlying pathology of mammary carcinogenesis.