Estrogen hormone therapy can cause cancer

Nearly 11,000 American women received a letter from the National Institutes of Health (NIH) this past Monday explaining that the estrogen hormone therapy clinical trial they had been involved in was being stopped a year earlier than planned due to the unacceptable health risks associated with the treatment.

These women were taking part in the Women’s Health Initiative (WHI), a large set of trials studying nutrition, hormone therapy and health outcomes. The women in this particular trial were taking estrogen therapy for a variety of reasons, including easing menopause symptoms, increasing bone density and reducing their risk of heart disease, but a safety review board at the NIH determined that the risk of stroke had become significantly high enough that the trial needed to be halted, and the agency informed participants that estrogen therapy conferred no protection against heart disease, inform &to=http://daily.stanford.edu' target=_blank>DailyStanford

Hormone replacement therapy (HRT) with estrogen and progestin seems to reduce the risk of colon cancer in women who are past menopause, new research shows. However, the cancers that do occur seem to be more advanced than those seen in non-HRT users.

Most of the news regarding HRT in recent years has been bad. Just this week, the National Institutes of Health announced that the estrogen-only arm of the Women's Health Initiative (WHI) trial was being stopped early after the therapy was tied to an increased risk of stroke. This follows the termination of the estrogen/progestin arm in 2002 due to an observed increase in breast cancer, thrombosis, stroke, and heart disease events among HRT users.

"We were quite surprised to find that colon cancers in HRT users were of higher stage than those seen in controls," Chlebowski told Reuters Health. The cancers that occurred in HRT users usually affected more lymph nodes and were more likely to have spread to other organs, the results indicate, according to &to=http://www.reuters.com' target=_blank>Reuters.com