Approximately half (57 percent) of the women in the placebo group had a decline in mammographic density compared with 16 percent of the women in the EPT group. Forty-seven percent of the placebo group had a modest increase compared with 85 percent in the estrogen EPT group.
Among the postmenopausal women randomized to EPT, risk of breast cancer risk increased 3.6-fold in 20 percent, with the greatest increase in mammographic density.
The researchers also found that baseline and change in mammographic density were significantly associated with breast cancer risk in the EPT group. Comparing breast density from the first and second mammogram, they could "predict" the women at increased risk of developing breast cancer.
Consistent with the original findings of the WHI, the researchers reported an association between EPT and breast cancer risk; there was a 24 percent increased risk, which was explained by the change in breast density, according to Byrne.
In addition to considering change in breast density among postmenopausal women taking EPT, "baseline breast density needs to be incorporated more in thinking about breast cancer risk," said Byrne. "We need to better understand patients who aren't on estrogen and progestin therapy and what makes some women's breast density decline and others stay high."
3768. Comparison of breast density measured by dual energy X-ray absorptiometry with mammographic density among adult women
Embargo: 9:00 a.m. ET, April 20, 2010
Measuring breast density by dual energy X-ray absorptiometry (DXA) may provide a low-radiation option to evaluate breast density for women who do not undergo mammography.
According to lead researcher Gertraud Maskarinec, M.D., Ph.D., it is important to study breast canc
|Contact: Jeremy Moore|
American Association for Cancer Research