Skeletal manifestations of treatment of breast cancer

Abstract

Breast cancer and osteoporosis are common diagnoses in women. Breast cancer survival has improved due to earlier detection and improved treatments. As most breast cancers are estrogen receptor positive, treatment is often aimed at altering the hormonal environment. Both pre and postmenopausal women undergoing these therapies are at risk for bone loss. The patient's health care team ought to have an awareness of the potential for breast cancer treatments to accelerate bone loss. Women with early stage breast cancer are treated with curative intent and, therefore, maintaining bone health is important and is part of the survivorship care to ensure an optimal quality of life.

Fig. 1

Action of estrogen on osteoblasts and osteoclasts. The principal activator of osteoclast-mediated bone resorption is the ligand of the receptor associated with nuclear factor kappa-B (RANK-L), which is expressed on the surface of osteoblasts [12]. Binding of RANKL to the RANK receptor on osteoclasts stimulates osteoclast differentiation [12]. Osteoprotegerin (OPG) is an endogenous inhibitor of the RANK/RANKL pathway and is secreted by osteoblasts. OPG binds to RANKL preventing its attachment to the RANK receptors. The presence of estrogen decreases the expression of RANKL on osteoblast cells, as well as increases the expression of OPG, allowing increased neutralization of RANKL, and stimulates apoptosis of osteoclasts [12]