Bone alkaline phosphatase and osteocalcin as markers of osteoporosis in postmenopausal women with breast cancer and bone metastases.

Objective(s): Breast cancer (BC) is a heterogeneous tumor that occurs predominantly in elderly women. The overall estimated number of new BCs in the USA in 2011 was 232,000, accounting for about one-third of cases of cancer in women. It continues to be one of the most common causes of cancer death. BC frequently metastasizes to the skeleton, and it is estimated that 85% of individuals with advanced disease harbor bone metastases (BM). Bone alkaline phosphatase (BAP) and osteocalcin are widely used to check the response to therapy in patients with progressive bone disease. The aim of this study was to evaluate whether a correlation exists between bone remodeling serum markers BAP and osteocalcin, and BMD in women with BC and BMs. Material & Methods: Data from a group of 18 postmenopausal women (median age 65 years, range 54-74 years) who have undergone surgery for invasive BC and successively developed BMs were retrospectively analyzed. Lumbar spine (L2-L4) BMD using DXA, and serum BAP and osteocalcin were measured in all patients. According to the WHO criteria, 13 patents (subgroup A) had mild or moderate osteoporosis (T-score -2.5 through -4 SD), while 5 (subgroup B) had severe osteoporosis (T-score of<-4 SD) Results: Age (62.2±5.6 vs. 68.8±4.2 years, p=0.061), baseline BAP (27.8±7.3 vs. 34.8±7.4 U/L, p=0.088) and osteocalcin (22.8±7.4 vs. 31.4±8.7 ng/mL, p=0.081) did not differ significantly (subgroup A vs. B). There was no relationship between age, BMD, BAP and osteocalcin serum levels in subgroup B, while in the subgroup A, only a week correlation (R=0.72, p=0.018) between BAP and osteocalcin was observed, and no relationship (p=NS) between BMD, age, and serum markers was found. Conclusion(s): In patients with BMs from advanced BC, the action of local osteolytic factors, such as PTHrP, together with direct bone resorption by lytic metastasis, may cause a severe bone disease. In postmenopausal women with BC and BMs the effects on bone of age and cancer together likely overlap, and the relationship between age, BMD, and bone remodeling serum markers is not maintained. References: Lumachi F et al. Anticancer Res 2009;29:1551.