The interplay between HT, density, and breast cancer

Citing density's masking effects on mammography in his presentation at the NAMS meeting, Bo von Schoultz, MD, PhD said breast density may be a target for intervention by lowering doses of postmenopausal women's hormone therapy. "The most density will occur with long-term standard combined hormone therapy," he said, "although every individual has her own baseline density. A significant portion will get a major density when taking hormones; others respond very little." However, as shown by the estrogen-only arm of the Women's Health Institute study, there may be a reduced risk when taking estrogen without a progestin.

Hence the need for safer regimens, reflected in the subject of his talk: "Lowering the dose of EPT: Efficacy and safety." Dr. von Schoultz shared results of a study of a subpopulation of 255 postmenopausal women from Nordic countries in the CHOICE trial, for which mammograms were done before the participants began treatment and after 5 to 6 months.

The study compared the effects of two low-dose combinations of estrogen and progestogen therapy: 0.5 mg estradiol (E2) plus 0.25 mg or 0.1 mg of norethindrone acetate and placebo, on mammographic density. Using the Wolfe classification and two other methods, no increase in breast density was found in any study group. "Although our results seem promising, this was a secondary objective of this study, so larger prospective studies are needed to confirm this new finding," he concluded.

Boyd NF, Fuo H, Martin LJ, et al. Mammographic density and the risk and detection of breast cancer. N Engl J Med. 2007;356:227-236.

Lundstrom E, Bygdeson M, Svane G, et al. Neutral effect of ultra-low-dose continuous combined estradiol and norethisterone acetate on mammographic breast density.