Researchers from The University of Texas M. D. Anderson Cancer Centre have identified certain risk factors that may help predict the likelihood of patients developing breast cancer in the opposite breast.
These risk factors may help women who are diagnosed with breast cancer make the difficult decision about whether to have their second breast removed as a preventive step.
"Women often consider contralateral prophylactic mastectomy (CPM) not because of medical recommendation, but because they fear having their breast cancer return," said Kelly Hunt, M.D., professor in the Department of Surgical Oncology at M. D. Anderson and lead author on the study.
"Currently it is very difficult to identify which patients are at enough risk to benefit from this aggressive and irreversible procedure. Our goal was to determine what characteristics defined these high-risk patients to better inform future decisions regarding CPM," she added.
During the study, the researchers reviewed the cases of 542 women with breast cancer only in one breast who received CPM to remove the second breast.
Out of this group, 435 patients had no abnormal pathology identified in the opposite breast, 25 patients had contralateral breast cancer identified at surgery, and 82 patients had abnormal cells that indicate a moderate to high-risk for breast cancer development in the contralateral breast found at the time of surgery.
Further analysis of the patients with contralateral breast cancer revealed that a five-year Gail risk of 1.67 percent or greater; an invasive lobular histology; and multiple tumours in the original breast were all strong predictors for contralateral breast cancer.
However, patient race, estrogen receptor status and progesterone receptor status were not associated with increased risk.
"We went from having very little information on the benefit of this procedure for individual patients to identifying three independent and significant risk factors," Hunt said.
"Each provides valuable insight into how likely a woman is to develop the disease in her other breast and enables physicians to make an educated recommendation if a patient will potentially benefit from CPM.
"We've always known contralateral breast cancer risk is not the same for all women and it is unnecessary to perform preventive mastectomies routinely.
"As we begin to clarify the specific risk factors, the number of women undergoing CPM may decrease and those with a low to moderate-risk may be more open to less extreme options for risk reduction, such as hormonal therapy and newer agents for prevention of breast cancer," she added.
The findings are published in journal Cancer.