Bone mineral density and bone remodelling markers osteocalcin and alkaline phosphatase in patients with Stage IV breast cancer

Background: Metastatic breast cancer (BC) is a severe disease, which frequently involves the bone. Direct bone resorption by lytic metastases, together with the action of local osteolytic factors, such as parathyroid hormone-related protein, is the mechanism causing malignancy-related hypercalcemia. Total alkaline phosphatase (AP) is a widely used test in metastatic bone disease, while osteocalcin is a specific marker whenever resorption and formation are uncoupled. In all patients with bone metastases (BMs), fracture risk identification has become an important aspect, especially in those who underwent hormone therapy. Thus, an evidence-based algorithm is needed to assess the risk and provide the correct therapy. The aim of this study was to evaluate the relationship between BAP, osteocalcin, and bone mineral density (BMD) in patients with Stage IV BC. Patients and methods: A series of 21 (median age 64 years, range 56–70 years) postmenopausal women with BC and confirmed BMs (Group A) underwent lumbar spine measurement of BMD using dual-energy Xray absorptiometry (DXA). Twenty-five age-matched women with Stage I–II BC represented the control group (Group B). Serum calcium, PTH, creatinine, and other routine biochemical parameters were normal in all patients. Results: Both serum AP (51.2±4.8 U/L vs. 39.6±5.4 U/L, p<0.001), and BMD (0.794±0.114 vs. 0.864±0.103 g/ cm2, p=0.03) were significantly different between Groups (A vs. B), while osteocalcin serum levels (25.1±9.1 vs. 27.5±7.2 ng/mL, p=0.32) did not differ. In Group A patients no correlations between BMD and both osteocalcin (R=−0.39, p=0.08) and BAP (R=−0.42, p=0.06), and between age and AP (R=0.37, p=0.10) were found, while there was a strong relationship between osteocalcin and both AP (R=−0.58, p=0.006) and age (R=0.47, p=0.03). No correlation (p=NS) was found in the control group. Conclusions: Inwomen with BC and metastatic bone defects, both bone remodelling marker measurement and DXA may be useful to identify patients at risk of pathologic fractures.