ANDRE PICARD
Globe and Mail (February 5, 2009)
A woman taking hormone replacement therapy for the treatment of symptoms of menopause will see her risk of breast cancer drop sharply as soon as drug use is discontinued, according to a new study.
The research, published in today’s edition of the New England Journal of Medicine, confirms that the longer a woman takes HRT, the greater her risk of breast cancer, and that after five years’ use the risk doubles annually.
But the risk of cancer is lower with short-term use - less than five years — and it returns to normal quickly if a woman stops taking the estrogen-progestin combination that usually makes up HRT.
The data also seem to confirm that the marked reduction in breast-cancer cases in countries such as Canada and the United States is due to the fact that millions of women stopped taking HRT in the wake of damning research findings.
Earlier studies showed significant drops in breast cancer in recent years, but some analysts said it might be due to other factors, such as changes in screening. For instance, fewer women might have been getting mammograms, which could have resulted in a drop in the number of cancer cases detected.
However, the new study shows breast-cancer risk is unrelated to rates of mammography, which points to falling HRT use as the most likely explanation.
Still, the experts remain divided on the safety and utility of hormone replacement therapy.
Rowan Chlebowski, chief investigator at Los Angeles Biomedical Research Institute and lead author of the new study, contented himself with saying that “postmenopausal women and their physicians should consider these findings in weighing the risks and benefits of combined estrogen plus progestin use, especially if the women plan to take the medication for more than five years.”
Barbara Mintzes, a professor in the department of anesthesiology, pharmacology and therapeutics at the University of British Columbia in Vancouver, said the research provides more compelling evidence that women should not be taking HRT to treat menopausal symptoms.
She said the distinction between short-term and long-term use was largely artificial. “If you know something is carcinogenic, why would you take it for four years instead of five?”
Robert Reid, chairman of the division of reproductive endocrinology and infertility at Queen’s University in Kingston, Ont., took the opposite view, saying the research is good news for women who choose HRT to treat symptoms of menopause, such as hot flashes.
He said the paper confirms that the increase in risk is slight and drops off entirely when HRT treatment ceases.
Dr. Reid said that, among women taking HRT, there will be eight new cases of breast cancer in every 10,000 users. “Stopping treatment will lower your risk, but how much will it really go down?” he asked.
The debate about the safety of HRT has been raging since the publication of research in 2002. The massive Women’s Health Initiative study concluded that women taking estrogen and progestin together had higher rates of breast cancer and heart disease, and those who took estrogen alone had a higher risk of stroke.
That highly publicized research led to a sharp drop in HRT prescriptions, to about five million last year from 12 million in 2002.
Just last month, the Society of Obstetricians and Gynaecologists of Canada issued new guidelines that essentially rehabilitated hormone therapy, saying it was effective and safe for periods of up to five years.
That move outraged many women’s health groups, who complained that the SOGC was too closely allied with pharmaceutical companies.
Heather Logan, director of cancer control policy at the Canadian Cancer Society, said that group’s recommendation remains unchanged. It urges women to take HRT only for treatment of serious symptoms of menopause, and then to keep the dose as low as possible and the duration of treatment as short as possible.