Author(s): Confavreux CB, Fontana A, Guastalla JP, Munoz F, Brun J,
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Abstract Aromatase inhibitors have demonstrated their superiority to tamoxifen as adjuvant therapy for early breast cancer in postmenopausal women, but are associated with an increased risk of fractures. The aim of our study was to analyze bone loss, bone turnover and their determinants in postmenopausal women treated with anastrozole. We investigated bone loss and bone turnover markers (BTM) in a prospective open cohort study of 118 postmenopausal women treated with anastrozole for an early hormone-dependent breast cancer. Women without osteoporosis were not treated and compared with an age-matched control group of 114 healthy women. Osteoporotic patients (T-scoreor=6 courses) and a marked antiestrogenic response--defined by a level of 17beta-estradiol50\% between baseline and 1 year--were associated with greater bone loss. In multivariate model, women in the highest quartile of bone loss at the spine (>5.6\% at 1 year) and hip (>4.9\%) had a marked antiestrogenic response with OR of 10.4 [95\% C.I. 1.9-57.2] (p=0.007) and 5.7 [1.3-25] (p=0.024) respectively. Among patients in the surveillance group, those with a normal T-score at both sites (n=46) had also a significant bone loss at spine -3.3+/-0.5\% [-4.3 to -2.3], p<0.0001 and at the hip -2.9+/-0.6\% [-4.1 to -1.7] p<0.0001. In osteoporotic women treated simultaneously with anastrozole and risedronate, bone loss was prevented at hip, and increased at the spine (+4.1+/-0.9\% [2.3 to 5.9], p=0.008), and BTM decreased (-24\%, -39\% for CTX, p=0.003 and 0.001 vs. changes in the untreated group). Anastrozole increases bone turnover and induces an accelerated bone loss that is significantly related to the suppression of 17beta-estradiol production induced by aromatase inhibitor. The bisphosphonate risedronate prevents anastrozole induced bone loss.
This article was published in Bone and referenced in Journal of Cancer Science & Therapy