Findings from an analysis published in the New England Journal of Medicine suggest that women who took long-term combined hormone replacement therapy with oestrogen and progestin experienced a marked decline in the risk of developing breast cancer soon after they stopped taking the treatment, and that the drop was unrelated to changes in frequency of mammography.

Researchers examined data from a group of more than 15 000 women who had been randomised to take either Wyeth’s Prempro (oestrogen and progestin) or placebo in the Women’s Health Initiative (WHI) trial. In addition, investigators analysed data from a separate WHI observational study that had begun in 1994 and involved over 41 000 women who had either chosen to take, or not to take, HRT.

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The randomised WHI clinical study was stopped in 2002 due to findings that women taking the therapy were at higher risk of breast cancer and other health problems. Regarding results from the observational study, the authors commented that “the incidence of breast cancer was initially about two times as high in the group receiving menopausal hormones as in the placebo group, but this difference in incidence decreased rapidly in about two years, coinciding with year-to-year reductions in combined hormone use.” They noted that the elevated risk of breast cancer decreased rapidly in both groups of women after they stopped taking HRT.

Responding to the findings, spokesperson Gwendolyn Fisher of Wyeth remarked that the study in the NEJM “does not support the theory that the decline in hormone therapy use, specifically oestrogen-plus-progestin use, caused the one-time abrupt nationwide decline in breast cancer incidence.” She suggested that the decline in breast cancer could be due to an increase in mammography during the 1990s, and the subsequent identification of a large number of cancers. Fisher also questioned why the authors “don’t offer an explanation of why breast cancer rates remain stable today when HRT rates continue to decline.”

Source: FirstWord

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