Characterization of bone mineral density (BMD) at the time of diagnosis in postmenopausal patients with operable breast cancer: Association with clinical-pathological findings

Abstract

9611 Background: Estrogen is involved in the pathogenesis of breast cancer. Because bone contains estrogen receptors and is, therefore, highly sensitive to levels of circulating estrogen, bone mineral density (BMD) may be a surrogate marker of a woman’s long-term exposure to endogenous estrogen. Some studies suggest that women, especially postmenopausal women with high BMD, have an increased risk for breast cancer. Methods: In this study we evaluate the association of BMD at the time of diagnosis with clinical-pathologic findings (history of hormone replacement therapy, existence of in situ component, estrogen and progesterone receptor concentrations, tumor size, nodal status, stage, grade, existence of lympho-vascular invasion, and histology) in patients with operable postmenopausal breast cancer. 117 patients were identified as having undergone BMD measurement at the time of their breast cancer diagnosis. Lumbar spinal, total hip BMD were measured by dual-energy X-ray absorptiometry. Patients were divided into two groups based on the median BMD. The median spinal BMD was 0.93 (0.56 - 1.48) gr/cm2 and the median total hip BMD was 0.85 (0.54 - 1.23)gr/cm2 Results: Median age at diagnosis was 62 (range 49 - 83). Sixty-two patients had stage I disease and 55 had stage II disease. Patients with higher BMD were found to have low grade disease, (P=0.01 for lumbar spine BMD and P=0.09 for total hip BMD), no lymphovascular invasion (P=0.02 for lumbar spine BMD and P=0.03 for total hip BMD) and progesterone receptor-positive tumors (P=0.05 for lumbar spine BMD). Patients with low Ki-67 level also tended to have high BMD P=0.06 for lumbar spine BMD). Conclusions: In our study cohort, high BMD at the time of their breast cancer diagnosis was associated with several favorable prognostic factors. High BMD might be related to higher circulating estrogen levels in these women. Further studies with a larger patient population are needed to determine whether high endogenous estrogen levels and high BMD is also associated with favorable prognostic features and outcome in breast cancer. No significant financial relationships to disclose.