Menopausal women who took estrogen and progesterone faced a small increased risk for cancer for more than two years after they stopped taking the pills, researchers said on Tuesday.
The study showed that virtually all the benefits disappear but that a slightly higher risk for breast and other cancers persists for at least three years after stopping the drugs.
The findings are the outgrowth of a large study on hormone replacement therapy, or HRT, in menopausal and post-menopausal women called the Women's Health Initiative, sponsored by the U.S. National Institutes of Health. The Women's Health Initiative study was halted prematurely in 2002 because of a 24 percent higher risk of breast cancer associated with the combination therapy of estrogen and progestin.
The extra cancer risk among former hormone users means an added annual risk of 0.3 percent for an individual woman, or three additional cases of breast or other cancers a year among 1,000 women.
The good news is that after women stop taking combination hormone therapy, their risk of heart disease appears to decrease, said Dr. Elizabeth Nabel, director of the National Heart, Lung, and Blood Institute, part of the U.S. National Institutes of Health that sponsored the original WHI study.
However, these findings also indicate that women who take estrogen plus progestin continue to be at increased risk of breast cancer, even years after stopping therapy, Nabel said in a statement.
Rowan Chlebowski, a medical oncologist at the Los Angeles Biomedical Research Institute and one of the study's principle investigators, said the risk of heart disease returns to normal after a woman stops taking the hormones, and that is good news.
But the cancer increase was unexpected, said Chlebowski. It raises just a new concern about [the] estrogen plus progestin kind of use.
What we're saying here now is that taking a short term [treatment] for symptoms, which many women have, seems still like a very good idea, said Chlebowski.
But I think the concept that we can reduce disease by taking a pill and predicting what's going to happen ten years later sounds like it's a very difficult process.
The study's authors recommend that women who received hormone replacement therapy with estrogen and progestin for 3.5 to 8.5 years undergo regular cancer screenings.