Bone mineral density and bone turnover in postmenopausal women treated for breast cancer

Chemotherapy and endocrine treatments for breast cancer are believed to increase risk of osteoporosis by causing early menopause in premenopausal women and by further depleting estrogen levels in postmenopausal women. Multivariate analyses were used to evaluate the contributions of 7 predictors (age, body mass index [BMI], family history of osteoporosis, months since menopause, past use of chemotherapy, and current use of tamoxifen or aromatase inhibitors) in explaining variability in bone mineral density (BMD) at the hip and the spine and bone turnover in 249 postmenopausal women who are breast cancer survivors. This report was an analysis of baseline data from a federally funded (1 R01 NR07743-01A1) intervention study on osteoporosis prevention. Mean age of the women was 58.5 years, and average BMI was 26.7 kg/m; 98% were white. All had measurable bone loss, 167 had chemotherapy, 76 were on tamoxifen, and 21 were on aromatase inhibitors. Women with higher BMI had higher BMD at the hip (P < .001) and the spine (P = .004). Women on tamoxifen had lower measures of bone formation (Alkphase B) (P < .001), suggesting less bone turnover, and higher BMD at the hip (P = .035). There was a trend for women who had received chemotherapy to have lower BMD at the spine (P = .06). The implications of these findings are discussed in the article.