To the Editor.
—In their Editorial, Dr Insogna and coauthors1 misquote the report of the Study of Osteoporotic Fractures.2 In doing so, they appear to miss their main point. In their report, Cauley et al state: "Our findings suggest that the risk of breast cancer associated with hormone replacement therapy may have been underestimated by previous investigators [emphasis added] because osteoporosis is a primary indication for its use." Cauley et al do not purport to show direct evidence that HRT is associated with breast cancer but do show that bone mineral density is correlated with breast cancer risk. A direct corollary of this is that patients with low bone mineral density (ie, with osteoporosis) have a lower risk of breast cancer than patients with normal bone mineral density. Thus, if users of HRT are more likely to have osteoporosis than nonusers, yet users are found to have the same breast cancer
Atkins CD. Estrogen Replacement Therapy: New Options, Continuing Concerns. JAMA. 1997;277(19):1515. doi:10.1001/jama.1997.03540430027016