Posted Feb 16, 2009
Women who take combined estrogen-progestin hormone therapy for at least five years increase their risk of breast cancer, according to a Stanford University study.
The study confirms findings of a landmark 2002 report by the Women’s Health Initiative.
However, Ellen Matloff, director of Cancer Genetic Counseling at the Yale Cancer Center, said women should not end their hormone-replacement therapy without weighing the risks and benefits with their doctors.
“When you look at the average risk to the average woman who is using hormone-replacement therapy, their average risk is quite small,” Matloff said. “It might be that, before this, 10 of 1,000 women were at risk for breast cancer, and now it might be 18 (of 1,000).”
After the 2002 study was published, hormone therapy prescriptions dropped from 60 million in 2001 to 20 million in 2005, according to a Stanford University Medical Center. However, not all doctors agreed that ending hormone therapy was the reason.
The new study settles the question, according to Marcia Stefanick, professor of medicine at Stanford University School of Medicine and a coauthor of the study.
“This is very strong evidence that estrogen plus progestin causes breast cancer,” said Stefanick. “You start women on hormones and within five years, their risk for breast cancer is clearly elevated. You stop the hormones and within one year their risk is essentially back to normal. It’s reasonably convincing cause-and-effect data.”
Results of the multi-center study were published in Thursday’s issue of the New England Journal of Medicine. The results do not apply to women who take estrogen only, such as those who have had hysterectomies.
The study looked at two groups of women, 15,000 in the original Women’s Health Initiative Study and 41,449 women in a separate trial started in 1994. Breast cancer rates in the first group dropped 28 percent within a year of ending hormone-replacement therapy, Stanford researchers found. In the second, half of the women stopped using estrogen-progestin therapy; they experienced a 43 percent drop in breast cancer rates, the study found.
Matloff said stoppinghormone therapy carries risks and side effects as well, such as osteoporosis, night sweats, depression, mood swings and loss of sex drive and functioning.
If a woman stays on estrogen-progestin therapy, “I would encourage her to take a step back, speak to her physician and weigh whether the risks outweigh the benefits before you go off our medication,” Matloff said. “I would just advise some caution.
Date Feb 14, 2009
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