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Due to an increased cancer risk, women should avoid combination hormone replacement therapy (HRT) for any reason other than to relieve severe menopausal symptoms that have not responded to other treatments, the Canadian Cancer Society announced in January, 2004.
"Recent research shows that long-term use of combined hormone replacement therapy increases breast cancer risk in women over 50, as well as risks for other diseases, including heart disease, stroke and blood clots in the lungs," says Heather Logan, Director, Cancer Control Policy, Canadian Cancer Society. "Current evidence shows that the risks of combined HRT use outweigh the potential benefits."
For women with severe menopausal symptoms who may be thinking about taking combined estrogen plus progestin HRT, the Society recommends that this decision be made with a doctor to assess risks and benefits. These include:
- the woman’s individual and family history of breast and ovarian cancer, heart disease, osteoporosis and dementia;
- how severe the woman’s menopausal symptoms are;
- how long the woman will be taking HRT.
"What we’re saying now, based on current research, is that if a woman and her doctor decide that taking combined hormone replacement therapy is right for the woman it should be used for the shortest time possible to control the symptoms for which it was started," says Logan.
Logan adds that the increase in breast cancer risk, and risk of other diseases, is also an important public health issue. "When you consider the number of women taking combined hormone replacement therapy, this definitely becomes an issue from the viewpoint of overall public health. The possible increased number of women being diagnosed with breast cancer is a concern."
The Society’s new recommendation is based on the results of a large, well-designed study in the United States called the Women’s Health Initiative (WHI). There are several studies within the WHI, including the combined estrogen and progestin study.
The combined estrogen plus progestin study involved more than 16,600 postmenopausal women aged 50 to 79 years with a uterus who took hormone replacement therapy consisting of estrogen plus progestin or a placebo. The trial was designed to examine the effect of this form of HRT on the prevention of heart disease and hip fractures, and to identify any associated risk for breast and colon cancer. The trial was stopped after an average of 5.2 years (planned duration was 8.5 years) because of an increased risk of invasive breast cancer, and evidence that overall health risks exceed any benefits.
The study found that for every 10,000 women taking estrogen plus progestin, when compared to 10,000 women not taking the combination therapy, per year of hormone replacement therapy use, there would be:
- 8 more women with invasive breast cancers (38 taking HRT vs. 30 not taking HRT)
- 7 more women with a heart attack (37 vs. 30)
- 8 more women with a stroke (29 vs. 21)
- 18 more women with blood clots in a vein (34 vs. 16), including 8 more with blood clots in the lungs
- 6 fewer cases of colorectal cancer (10 taking HRT vs. 16 not taking HRT)
- 5 fewer hip fractures (10 vs. 15).
If you count up the added cases of breast cancer, heart attacks, strokes and blood clots in the lungs and subtract the fewer cases of colorectal cancer and hip fractures, there are about 30 extra harmful events among the 10,000 women taking hormones after 5.2 years, the period the study ran.
The Canadian Cancer Society is a national community-based organization of volunteers whose mission is to eradicate cancer and to enhance the quality of life of people living with cancer. For more information: visit www.cancer.ca or call 1-888-939-3333.
For more information on the Pros and Cons of HRT, visit: www.cwhn.ca/resources/hrt/index.html