Relationships between Body Mass Index, Serum Leptin Levels, and 17β-Estradiol in Postmenopausal Women with Breast Cancer: A Case-Control Study

Introduction: There is a close relationship between the incidence of breast cancer and fat intake in different populations. Overweight and obesity during menopause can increase the risk of breast cancer in women. Hormones like estrogen and leptin are factors that affect the growth and proliferation of breast cells. The main purpose of this study was to evaluate the relationships between body mass index (BMI) and serum levels of leptin and 17β-estradiol in postmenopausal women with breast cancer. Methods: Seventy-nine postmenopausal women with breast cancer and Seventy-nine healthy postmenopausal women, aged 50-75 years, were recruited for the study. After obtaining written informed consent and demographic data, blood samples were taken from all participants to assess the serum concentrations of hormones using ELISA. Results: The mean BMI was 25.59 ± 0.34 kg/m2 for the cancer group, 23.21 ± 0.22 kg/m2 for the control group  (P = 0.001). The difference in serum concentration of 17beta-estradiol between the cancer group and the control group was significant (54.27 ± 1.91 and 46.44 ± 1.36 pg/ml, respectively, P = 0.001). The mean serum leptin level was significantly lower in the cancer group (41.05 ± 3.10 ng/ml) than in the control group (53.05 ± 4.83, 53 ng/ml) (P = 0.036). Conclusion: Body mass index in both groups was significantly and positively correlated with serum levels of 17β-estradiol, but there was no significant correlation between BMI and serum leptin concentration. Postmenopausal women with BMI ˃ 25 and high serum concentrations of 17β-estradiol are probably susceptible to breast cancer.