Hormone Replacement Therapy Even for Short Periods Raises Breast Cancer RiskJan 16, 2008 | Parker Waichman LLP
U.S. researchers reported this week that hormone replacement therapy (HRT) significantly raises the risk of an uncommon type of breast cancer. The study found women who took combined estrogen/progestin HRT for three years or more had four times the usual risk of lobular breast cancer. The study, published in the January issue of Cancer Epidemiology, Biomarkers and Prevention, is one of dozens of studies looking to clarify the dangers of taking HRT to treat menopause symptoms. "Previous research indicated that five or more years of combined hormone-therapy use was necessary to increase overall breast-cancer risk," Dr. Christopher Li of the Fred Hutchinson Cancer Research Center, who led the study, said. "Our study, the first specifically designed to evaluate the relationship between combined HRT and lobular breast cancers, suggests that a significantly shorter length of exposure to such hormones may confer an increased risk," he added.
According to the American Cancer Society, lobular breast cancer accounts for about 10 percent of all invasive breast cancers, the cancers that most threaten to spread to other parts of the body. The cancer can be treated with hormone-based therapies such as tamoxifen, but the tumors are more difficult to detect by mammograms, so that the cancer is generally diagnosed in more advanced stages.
Li's team asked over 1,500 post-menopausal women in western Washington whether or not they had used HRT; 1,044 women had breast cancer and 469 did not. The researchers found that women currently taking HRT were about three times as likely as other women to be among the cancer patients and those who used combined HRT for three or more years had a higher risk of lobular cancer. They also said that the incidence of invasive lobular cancer rose by 52 percent in the United States between the years 1987 to 1999. Also, cases of ductal-lobular breast cancer rose by 96 percent during and ductal cancer rates rose by three percent over the same time period. "Our research suggests that the use of post-menopausal hormone-replacement therapy, specifically the use of combined estrogen-plus-progestin preparations, may be contributing to this increase," said Li.
Historically, doctors believed HRT could protect women from chronic diseases, especially heart disease. But use of HRT plunged after the 2002 Women's Health Initiative study found that HRT could raise the risk not only of breast and ovarian cancer, but also of strokes and other serious conditions. Research since also indicates that the incidence of breast cancer dropped by 8.6 percent between 2001 and 2004 in the United States, in conjunction with the decline in HRT use. Today, doctors stress that younger women who need the drugs to relieve serious symptoms of menopause should still consider taking HRTs because new, lower-dose formulations are available and doctors now know to prescribe them for short periods of time.
"These findings are still of considerable public-health importance considering the estimated 57 million prescriptions for menopausal hormone therapy that continue to be filled in the United States," Li said.