Study confirms risk of continuous combined hormone therapy.(breast cancer risk)

2003 JAN 2 - (NewsRx.com & NewsRx.net) -- Researchers confirmed that a daily, combined dose of estrogen and progestin increases breast cancer risk in post menopausal women, but added that this risk begins to return to normal about 6 months after women stop taking the hormones.

The analysis was part of the National Institute of Child Health and Human Development (NICHD) Women's Contraceptive and Reproductive Experiences Study. The majority of the study's funding was provided by the NICHD. The Centers for Disease Control and Prevention contributed additional staff and computer support for the study. The National Cancer Institute also provided additional funding.

"It is reassuring that breast cancer risk begins to return to normal 6 months after women stop combined dose estrogen-progestin therapy," said Duane Alexander, MD, director of the NICHD, writing in the December 2002 Obstetrics & Gynecology. "Women, in consultation with their physicians, need to make the most informed decision possible. The study authors have provided them with one more piece of important information."

The NIH Women's Health Initiative (WHI) trial was the first large clinical trial to assess the risks and benefits of continuous combined hormone therapy. In July 2002, researchers stopped the WHI trial because the risk of breast cancer and heart disease from combined hormone replacement therapy outweighed its potential benefits.

In this form of therapy, women take a combination of the hormones estrogen and progestin. Essentially, the hormone estrogen relieves such symptoms of menopause as hot flashes, night sweats, sleeplessness, and vaginal dryness. When taken alone, however, estrogen also increases a woman's risk for cancer of the uterine lining, or endometrium. Combining estrogen with progestin virtually eliminates the risk of endometrial cancer.

"In planning the NICHD study, we sought to learn as much as we could about the risks associated with the various kinds of hormone therapy," said Robert Spirtas, DrPH, chief of NICHD's Contraception and Reproductive Health Branch and senior author of the study. "At the time, little information existed on whether combined hormone therapy posed the same risks as estrogen therapy alone."

In the WHI trial, women used continuous combined hormone therapy and researchers monitored their health during the course of the study. When it became clear that the women were developing breast cancer at higher-than-normal rates, the researchers stopped the trial. Because the study was stopped only recently, the WHI researchers cannot tell yet whether the women in the study face any increased risk of breast cancer now that they have stopped taking the hormones.