Breast Cancer Risk Subsides After HRT
Advice: Take Combined HRT at Minimum Dosage for Less Than 5 Years
However, six months after they quit taking continuous estrogen-progestin therapy, the women's risk of breast cancer began to return to normal. This was true for women who took HRT five years or longer before stopping.
Researchers also found that an alternate form of "sequential" hormone therapy -- which involves taking the hormones separately, on different days of the month -- did not seem to increase breast cancer risk. In this form of HRT, women take the hormone progestin for five to 14 days a month. However, earlier studies have suggested that this regimen may increase the risk of uterine cancer.
"It does appear that estrogen combined with progestin is a particularly dangerous combination when it comes to breast cancer," says JoAnn Manson, MD, principle investigator of the WHI.
Manson, who is chief of preventive medicine at Brigham and Women's Hospital in Boston, agreed to comment on Weiss' study for WebMD.
"We recommend that women avoid long-term use of estrogen plus progestin," Manson tells WebMD. "Estrogen-progestin use should be limited to treatment of severe hot flashes, to improve quality of life in the short term -- and it should be used in the lowest possible doses, for the shortest amount of time. There is very little increased risk of breast cancer with hormone use of less than five years."
Regarding sequential hormone therapy, "the jury is still out in terms of breast cancer risk and overall benefit-to-risk ratio," says Manson. "The evidence has just been too limited. There have been no large-scale, randomized clinical trials of it."
Thus far, the evidence -- as premature as it may be -- shows that sequential hormone therapy may be less hazardous in terms of breast cancer, she says. "I think if progestin is taken for at least 12 days per month, it's supposed to protect the uterus with no increased risk of breast cancer."
"It is premature to assume that it is safe in terms of breast cancer," she tells WebMD. "We need more research to assure women of that."
Her advice: "If women need the estrogen-progestin combination, it should only be for treatment of severe hot flashes that impair quality of life. The main point is to minimize duration and dose. Also, if a woman has a family history of breast cancer, it would be particularly prudent to avoid hormone replacement therapy."