Media Releases

Second diagnosis of breast cancer increased by mutation

April 20, 2011

TORONTO, ON – Women with BRCA mutations have an extremely high lifetime risk of developing breast cancer and an elevated risk of developing second primary cancer in the opposite breast, according to a recent study published in the British Journal of Cancer.

The study, Predictors of contralateral breast cancer in BRCA1 and BRCA2 mutation carriers, led by Bloomberg Faculty of Nursing professor Kelly Metcalfe, is the first to investigate the predictors of contralateral breast cancer in women with a BRCA1 or BRCA2 mutation, specifically reporting the influence of family history. The results indicate the risk of contralateral breast cancer declines with age, but increases with the number of first-degree relatives with breast cancer.

“These results have significant clinical implications and suggest that women with a BRCA mutation who are diagnosed with breast cancer have a high risk of developing a new cancer in the opposite breast,” says Metcalfe. “However, we have also shown there are treatments that can reduce this risk. With this information, women can make treatment decisions to reduce their risk of developing a new breast cancer.”

The effect of family history was only present for women with a BRCA mutation whose initial breast cancer was diagnosed at age 49 years or below. For these women, the 15-year risks of developing cancer in the opposite breast were estimated to be 33, 39 and 50 per cent for women with zero, one, and two or more first-degree relatives diagnosed with breast cancer under age 50, respectively.

There are also differences in the risks of contralateral breast cancer in women with a BRCA mutation according to age. Women diagnosed with breast cancer younger than 40 years of age had a 15-year risk of 42 per cent for developing cancer in the opposite breast compared with 19 per cent for women over the age of 50 at the time of diagnosis.

The risk is highest for women with intact ovaries, two or more first-degree relatives with breast cancer and who were diagnosed at age 49 or below, with a 15-year risk of contralateral breast cancer of 68 per cent.

The results demonstrate the importance of knowing BRCA status at the time of initial breast cancer diagnosis when making treatment decisions. In addition, it’s critical to recognize the modifiers of contralateral breast cancer in women with BRCA mutations to effectively counsel them on their personal risk and how treatment may modify this risk. For high-risk women, both oophorectomy (removal of the ovaries) and contralateral mastectomy (removal of the opposite breast) should be discussed as a component of treatment to reduce the risk of second primary cancer and prevent ovarian cancer.

This research was funded by the Canadian Breast Cancer Foundation (Ontario Chapter). Metcalfe is supported by the Canadian Institutes of Health Research and the Ontario Women’s Health Council.

The Lawrence S. Bloomberg Faculty of Nursing at the University of Toronto ranks among the premier nursing programs in the world in both education and research. In 2007, ours became the first named faculty of nursing in Canada. We are committed to ensuring the approximately 650 students in our undergraduate, masters and PhD programs have the highest quality learning experiences. Moreover, with a Faculty comprised of the country’s leading nurse researchers and educators, major contributions to knowledge, health policy and future practice are produced regularly.

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For a copy of Predictors of contralateral breast cancer in BRCA1 and BRCA2 mutation carriers, visit: www.nature.com/bjc

For more information, please contact:
Dr. Kelly Metcalfe, Associate Professor,
Lawrence S. Bloomberg Faculty of Nursing, University of Toronto
416.978.2851 or kelly.metcalfe@utoronto.ca

Sarah Gopaul, Communications Assistant,
Lawrence S. Bloomberg Faculty of Nursing, University of Toronto
416.946.3657 or sarah.gopaul@utoronto.ca