Osteoporosis and rate of bone loss among postmenopausal survivors of breast cancer

Abstract

Background: Breast cancer diagnosis and treatment may put women at higher risk for osteoporosis in later life.

Methods: In a subgroup of participants in the Women's Health Initiative Observational Study, authors of the current study investigated differences in bone mineral density (BMD, measured by dual-energy x-ray absorptiometry) between breast cancer survivors (n = 209) and a noncancer reference group (n = 5759).

Results: In comparison to the reference group, breast cancer survivors had significantly lower total body BMD value (0.989 vs. 1.013 g/cm(2), P = 0.001) and total hip BMD value (0.823 vs. 0.845 g/cm(2), P = 0.02) at baseline after adjustment for age, race/ethnicity, years since menopause, and clinical center. These lower BMD levels were largely explained by lower usage of hormone therapy (HT) among survivors: after additional statistical adjustment for HT, hip BMD values were 0.834 versus 0.844 g/cm(2) (P = 0.26), and total body values were 1.005 versus 1.013 g/cm(2) (P = 0.33) for survivors and reference women, respectively. More than 77% of survivors with osteoporosis were undiagnosed by their healthcare providers, and this was similar to the undiagnosed rate in the reference group (85.7%). Longitudinally, breast cancer survivors in this study did not demonstrate an accelerated rate of bone loss compared with the reference population.

Conclusions: Associated with lower HT usage, postmenopausal survivors of breast cancer were more likely to have low BMD in comparison to other women of the same age; and many of these survivors with osteoporosis were undiagnosed.