Contralateral Breast Removal Boasts Few Benefits

Contralateral prophylactic mastectomy (CPM) in women with early-stage breast cancer in one breast shows minimal survival benefit, according to a new study.

Researchers at the University of Minnesota (UMN; Minneapolis, USA) set out to evaluate the survival benefit of CPM for women with unilateral early-stage breast cancer—without a BRCA gene mutation—by analyzing data from the Early Breast Cancer Trialists’ Collaborative Group and the Surveillance, Epidemiology, and End Results program. They then developed a computer model that simulated a hypothetical cohort of women with stage I or II breast cancer, and examined the risk for developing contralateral breast cancer (CBC), dying from CBC, dying from primary breast cancer, and the reduction in CBC due to CPM.

The results showed that the gains in life expectancy with prophylactic mastectomy ranged from less than one month in a 60-year-old woman with estrogen receptor (ER)-positive, stage II breast cancer, to 6.3 months in a 40-year-old woman with ER-negative stage I disease. The absolute overall difference in survival at 20 years ranged from 0.36% to 0.94% for both patient groups. The study was presented at the 2013 Clinical Congress of the American College of Surgeons (ACS), held during October 2013 in Washington DC (USA).

“What we are trying to tell patients is that what is going to be potentially fatal is not a cancer that you may or may not get in the opposite breast. It’s whether or not this initial cancer has metastasized to your liver, lung, or brain,” said study presenter and coauthor Pamela Portschy, MD. “We hope that by providing women with accurate and easily understood information about the potential benefits for contralateral prophylactic mastectomy this may impact current trends.”

“Rates of CPM have escalated over the past 20 years. Close to 20% of women in the United States today who have cancer in one breast undergo a double mastectomy, up from about 1% in the mid-1990s,” added coauthor Todd Tuttle, MD, chief of surgical oncology at UMN. “Experts attribute the rise in CPM to a number of factors, such as increased use of magnetic resonance imaging, improved mastectomy and reconstruction techniques, and greater awareness of genetic breast cancer and BRCA testing.”

A woman's risk of developing breast and/or ovarian cancer is greatly increased if she inherits a mutation in the BRCA1 or BRCA2 gene, which produce tumor suppressor proteins. Specific inherited mutations in BRCA1 and BRCA2 increase the risk of female breast and ovarian cancers, and they have been associated with increased risks of several additional types of cancer. Together, BRCA1 and BRCA2 mutations account for about 20%–25% percent of hereditary breast cancers, and about 5%–10% of all breast cancers. Breast cancers associated with BRCA1 and BRCA2 mutations tend to develop at younger ages than sporadic breast cancers.

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