This substudy was supported by the Canadian Breast Cancer Research Alliance, a joint initiative between the Canadian Institutes of Health Research and the Canadian Cancer Society. The main MAP.3 study also was supported by Pfizer. Jamieson Laboratories provided calcium and vitamin D supplements and Pfizer Pharmaceuticals provided exemestane and placebo. Dr. Cheung is supported in part by a Canadian Institutes of Health Research/Institute of Gender and Health Senior Investigator Award, and the Lillian Love Chair in Women’s Health at the University of Toronto/University Health Network. One of Dr. Cheung’s associates reported ties to Pfizer and Avon Foundation. None of the other researchers reported conflicts of interest.
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Adverse Bone Effects ‘Substantially Underestimated’ Until Now
"Results of this study suggest that effects of aromatase inhibitors on bone strength might have been substantially underestimated because all previous data relied on dual-energy x-ray absorptiometry," which cannot assess volumetric bone density or trabecular and cortical microarchitecture, said Dr. Jane A. Cauley.
In contrast, high-resolution quantitative CT allowed separate examination of the cortical and trabecular compartments and found that exemestane substantially increased loss of cortical bone compared with trabecular bone. "This finding is important because 80% of our bone loss is cortical and 80% of all fractures occur in nonvertebral sites that are mainly cortical. These fractures account for most of the disability and costs due to fracture," she wrote.
Dr. Cauley is with the University of Pittsburgh. She reported no financial conflicts of interest. These remarks were taken from her editorial comments accompanying Dr. Cheung’s report (Lancet Oncol. 2012 [doi:10.1016/S1470-2045(12)70030-X]).
FROM THE LANCET ONCOLOGY