[Skip to Content]
[Skip to Content Landing]
April 17, 1996

Hormone Replacement Therapy and Breast Cancer Risk-Reply

Author Affiliations

University Hospital Uppsala, Sweden

JAMA. 1996;275(15):1159-1160. doi:10.1001/jama.1996.03530390024025

In Reply.  —Epidemiological data on the association between HRT and breast cancer risk still seem contradictory, both when comparing results of studies from within the United States and studies from the United States and Europe.1-3 Differences in design qualities and in study populations may be important explanations. The comments of Dr Harris and colleagues and Dr Campagnoli and colleagues, however, focus attention on biological mechanisms that might explain why HRT in some circumstances may exert an adverse effect on breast cancer risk.On the basis of subgroup analyses from several studies, Harris et al suggest that, compared with women with normal BMIs, the breast tissue in lean women is exposed to higher concentrations of estrogens, and therefore it may particularly susceptible. It might also be that exogenous hormones have a greater impact in lean women because they have relatively lower endogenous levels before treatment. The breast tissue may be