According to the American Cancer Society, more than 232,000 women are diagnosed with breast cancer in the U.S. every year,* making breast cancer the second most common type of cancer in women, after skin cancer. Many women who face this diagnosis worry about cancer recurring in the healthy breast and therefore choose to have both breasts removed, even though the risk of developing cancer in the other breast is very low. Women at high risk include those with a family history of breast or ovarian cancer and women who test positive for the BRCA1 and BRCA2 gene mutations.
Importantly, until now no study has looked at the decision-making processes that lead women to choose CPM. "There have been several studies in the last couple of years indicating that there may be a survival benefit for selected patients by having their healthy breast removed," said study coauthor Todd M. Tuttle, MD, FACS, chief of surgical oncology, University of Minnesota, Minneapolis. "This research will provide physicians and patients with accurate and easily understood information about whether removal of the healthy breast will impact their survival at all."
To better understand the effect of CPM on life expectancy, the researchers conducted an analytic modeling study among women without a BRCA gene mutation. Within this group, the researchers compared women who underwent CPM with women who did have early-stage breast cancer in one breast and no prophylactic operation to remove the second breast.
The study authors primarily analyzed data from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) and the Surveillance, Epidemiology, and End Results (SEER) program to determine the risk of developing contralateral breast cancer (CBC), dying from CBC, dying from primary breast cancer, and the reduction in CBC due to CPM. The two databases include information on the treatment and survival of early breast cancer and include more than 100,000 women who have participated in randomized trials over the last 30 years across the United States.
For the study, the researchers estimated the life expectancy gain of CPM among sub-groups of women newly diagnosed with cancer in one breast by age 40 to 60 years, estrogen receptor status as positive or negative, and stage of cancer I or II. They found that the maxi- mum life expectancy gain for women who underwent CPM was six months for all scenarios including age, estrogen receptor status, and cancer stage groups.
Because many women are driven by their fears of contracting a second cancer in their healthy breast, they choose a double mastectomy, the more aggressive treatment. This procedure is a bigger operation associated with a longer recovery period and potentially more complications. Thus, experts are concerned that some patients are being overtreated with a prophylactic procedure.
"I think this decision model study will provide women who are considering these extensive operations with more accurate information about whether or not CPM is going to improve their survival," Dr. Tuttle said. With this analytic modeling tool, women and physicians can make more informed and better decisions when choosing between different treatments. These results can help educate women that a contralateral mastectomy will not improve their survival rate if they don't have hereditary breast cancer, he explained.
"This information may ultimately help them answer an important question: 'If I have that opposite breast removed, is that procedure really going to improve the likelihood that I will be alive 10 to 20 years from now?'"