The Relationship between Bone Mineral Density and Estrogen Receptor Positivity in Patients with Breast Cancer

Abstract

IntroductionBreast cancer is the most prevalent cancer type and the second leading cause of death in women (1). Advanced age, early menarche, firstterm pregnancy at a late age, late menopause, and long-term hormone replacement treatment are among the risk factors for breast cancer (2-4). The relationship between these risk factors and breast cancer are reported to be due to the estrogen-induced increase in mitotic activity in breast tissue, which results in mutations (5).Estrogen hormone is an important risk factor for breast cancer; however, serum levels often vary, which obstructs correlating serum estrogen levels with the risk of breast cancer (6). Serum samples are not sufficient alone to diagnose breast cancer or identify the long-term estrogen level of tissues. Bone mineral density (BMD) should be considered a good indicator of tissue levels of estrogen because BMD elevates in parallel with the increase in estrogen level (7). Estrogen lessens bone destruction while amplifying bone volume and bone mineral density. When we consider this information, we may think that there is a correlation between BMD and breast cancer. Nevertheless, studies that investigated the relationship between bone mineral density and development of breast cancer revealed contradictory results (8-11).In patients with breast cancer, the ratio of tumor estrogen receptor (ER) positivity enhances with age. In a study carried out on Turkish women, ER was found positive in 66% of pre-menopausal women, and this rate increased to 73% in menopausal women (12). Only a few studies in the literature have shown a link of the change in ER positivity with bone density, but none were conducted in Turkey.The objective of this study was to compare the BMD of postmenopausal women with breast cancer with that of control subjects and thus to investigate the association between tumor estrogen receptor level and bone mineral density. J Breast Health 2016; 12: 119-22 DOI: 10.5152/tjbh.2016 12: 119-22 DOI: 10.5152/tjbh. .2961 119 ABSTRACT Objective: The effect of estrogen on bone mineral density (BMD) and breast cancer has been known for a long time. The aim of this study was to compare of the BMD of patients with breast cancer and healthy individuals, and to investigate the degree of correlation of estrogen receptor (ER) with BMD. Materials and Methods: Seventy-one patients with postmenopausal breast cancer and 79 healthy dividuals were included in the study. The patient demographics (age, menopause age, body mass index, number of children, BMD, Z scores, and estrogen status for breast cancer patients) were taken from hospital records. Results: No significant difference was detected between the case and control groups in lumbar region Z scores (p=0.074). At the femur neck, the control group Z scores was higher than patient group (p=0.002). BMI was higher in the patients with breast cancer (p=0.001). There was no statistically significant correlation between ER positivity, BMD, and BMI in ER-positive patients (p=0.495, p=0.8, p=0.846, respectively). There ...