Hormone Therapy Safe, Effective In Reducing Breast Cancer Risk

Ruzanna Harutyunyan's picture

New Canadian-led research published today in the Journal of the National Cancer Institute suggests hormone replacement therapy is associated with a 42 per cent reduced risk of breast cancer in postmenopausal women with a BRCA1 gene mutation.


In Canada, it is estimated 6000 women carry a BRCA mutation, which means they have an 80 per cent chance of developing breast cancer in their lifetime.i,ii However, this risk is greatly reduced by surgically removing the ovaries before menopauseiii, because ovary removal significantly decreases the amount of estrogen and progesterone circulating in the body (breast cancers need these hormones to grow.) This preventive surgery (ovary removal) has become the standard of care in North America and Western Europe for preventing both breast and ovarian cancer for women with BRCA1 mutations, but only 54 per cent of women in Canada with the gene mutation have this surgery performed.

The reluctance is because hormone therapy is perceived to increase the risk of breast cancer, even though it is used to alleviate the effects of surgical menopause. "The results of the study should be reassuring for women with a BRCA1 mutation who want to remove their ovaries before menopause to reduce their risk of developing breast and ovarian cancer, but are concerned about the effects of the hormone replacement therapy," said Steven Narod, M.D., Canada Research Chair in Breast Cancer & Program Director of the Familial Breast Cancer Research Unit at the Women's College Research Institute and professor of Public Health Sciences at the University of Toronto.

"This new information can provide some reassurance to women when they are making this tough decision about reducing their risk." The study observed a total of 472 postmenopausal women with a BRCA1 mutation. They came from 55 cancer research centres in nine countries. Half of the women were diagnosed with breast cancer. They were then matched and compared to a similar group of women with a BRCA1 mutation, but with no breast cancer diagnosis. Current age, age at menopause onset and the type and length of hormone therapy treatment were all considered in the analysis. Women without breast cancer were found to have used hormone replacement therapy more often than women with cancer.

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