Study Ties Hormone Therapy to Bolder, Stealthier Cancer
Hormone replacement therapy not only increases a woman’s risk of breast cancer, but also produces a more aggressive form of cancer and delays detection of tumors, both of which make it less likely that the cancer will be cured, according to a new report published today.
The findings are the latest in a drumbeat of bad news that suggests hormone replacement therapy is beneficial only for short-term use and under very restricted circumstances.
“Hopefully, [the new findings] will convince women to reconsider” beginning hormone therapy, said Dr. Susan Hendrix of Wayne State University in Detroit, one of the authors of the study in the Journal of the American Medical Assn. “We’ve got to find a better way to help women with their menopausal symptoms.”
In an editorial in the same issue, Dr. Peter H. Gann and Dr. Monica Morrow of Northwestern University added: “The message for physicians caring for menopausal patients is clear.... [The results] provide further compelling evidence against the use of combination estrogen plus progestin hormone therapy.”
Hormone replacement therapy, also known as HRT, has been widely used in post-menopausal women because of the belief that the treatment not only eases hot flashes and other acute symptoms of menopause, but also increases bone density, protects against heart disease and stroke, and delays the onset of dementia.
Within the last year, however, those beliefs have been completely overturned, largely as a result of the Women’s Health Initiative, a study of more than 16,000 women. That study was halted prematurely last year when it became clear that HRT increased the risk of breast cancer while providing no benefit against heart disease and stroke.
A further analysis of the data from that study, reported in May, found that HRT also does not protect against Alzheimer’s disease and other dementia.
In today’s report, the data from the Women’s Health Initiative were examined more closely by a team headed by Hendrix and Dr. Rowan T. Chlebowski of Harbor-UCLA Medical Center.
They found that women taking the hormones had a 24% higher risk of breast cancer than women taking a placebo, equal to about eight extra cases of breast cancer per year for every 10,000 women taking the pills. The increased risk became apparent in the third year of the study, Chlebowski said. It may have been present earlier, however, but masked by the increased breast density caused by HRT, which makes tumor detection more difficult.
At diagnosis, tumors were larger in the women taking hormones: an average of 1.7 centimeters in diameter compared to 1.5 centimeters in diameter among women taking placebos. Moreover, the tumors had already begun to spread throughout the body in 25.4% of hormone users, compared to only 16% of those receiving placebos.
This new analysis is by far the most conclusive, Gann and Morrow wrote. “Experienced observers hesitate to label any biomedical research study as ‘definitive’ ... [but this] is as close to definitive as can be expected.”
In a separate paper in JAMA, Dr. Christopher Li and his colleagues at Fred Hutchinson Cancer Research Center in Seattle reported on a study of 975 women, ages 65 to 79, who had used estrogen for long periods, either alone or with varying amounts of progestin.
They concluded that women who used the two hormones for long periods doubled the risk of breast cancer, even if progestin was used for only a few days per month. Surprisingly, however, they found no increased risk of breast cancer among women who used estrogen alone.
The use of estrogen without progestin is now recommended only for women who have undergone hysterectomies because it increases the risk of uterine cancer. Progestin is combined with estrogen to reduce that risk.
The number of women receiving only estrogen in Li’s study was relatively small, however, and it is still possible that there is an increased risk of breast cancer, he said. A more definitive answer is expected to be provided by an ongoing arm of the Women’s Health Initiative, which is studying estrogen use in a larger number of women. Those results are not expected for at least another year.
If estrogen alone does not increase breast cancer risk, Gann and Morrow noted, physicians may have to reevaluate the possibility of prescribing it for larger numbers of women.
