Hormone Study Finds Higher Breast Cancer Risk
Contrary to much current medical thinking, long-term use of hormone replacement therapy may significantly increase the risk of breast cancer in postmenopausal women, even when progestins are added to estrogen, according to a new study.
Although estrogen alone has long been associated with an elevated risk of breast cancer, most women taking the therapy use a combination of estrogen and progestin, which has been thought to be safer. However, today’s study in the New England Journal of Medicine found that even women taking a combination of the hormones had a significantly higher risk of breast cancer if they consumed the hormones for more than five years.
Women 60 and older were at the highest risk when undergoing long-term hormone therapy.
The study showed that short-term use of hormones was not associated with an increased risk of breast cancer. But many doctors now keep women on hormones for many years, even for life, because of estrogen’s demonstrated ability to ward off heart trouble and bone fractures. The latest research suggests such lengthy use may do more harm than good for some women.
“It clearly raises the need to reconsider the risk and benefit if a woman is going to use hormones for more than five years,” said Dr. Graham A. Colditz of Brigham and Women’s Hospital in Boston, the study’s principal author.
Some earlier studies have also found links between estrogen and breast cancer, others have not, and the issue has been heavily debated. But the latest report is the largest to examine the question. It was based on the Nurses’ Health Study, which has followed 121,700 female nurses since 1972.
Hormone replacement therapy’s benefits may still outweigh its hazards for women who are at high risk of heart trouble and osteoporosis. However, for those whose risk of these problems is low, the study says the increased chance of breast cancer may make hormone supplements a significant gamble.
The study found that women who took either estrogen alone or estrogen plus progestin for more than five years had a 46% higher risk of breast cancer than did those who never used the therapy.
The risk varies depending on the woman’s age. The researchers calculated that a 60-year-old woman who has used estrogen for at least five years has a 3% chance of developing breast cancer over the next five years if she keeps taking the treatment. If she had never used hormones after menopause, her risk over the same period would be 1.8%.
The study also found that long-term users’ increased risk of breast cancer drops back to normal within two years of stopping hormone therapy.
On the other hand, estrogen has been found to cut in half the risk of heart disease, which is the leading cause of death for women as well as men. It has a similar impact on fractures, a major cause of disability.
