According to findings published in the March 1, 2009 issue of Cancer, a preventive procedure to remove the unaffected breast in breast cancer patients with disease in one breast may only be necessary in patients who have high-risk features. The study was the work of Dr Kelly K Hunt and colleagues at the University of Texas MD Anderson Cancer Center in Houston.

Having breast cancer in one breast increases a woman's chances of getting it in the second breast, either at the same time or later. Finding out which women are most at risk of developing cancer in the other breast could help patients make better decisions about preventive treatment, such as whether to surgically remove the other breast. But are there any definite criteria that make this decision easier?

To attempt an answer to this question, Hunt and colleagues studied 542 patients who had breast cancer diagnosed in one breast (unilateral breast) and decided to have this and the other breast (contralateral prophylactic mastectomy) removed between 2000 and 2007. They then examined tissue specimens of the removed second breast and found that 25 of the patients (5 per cent) had breast cancer in the removed second breast and 82 (15 per cent) had abnormal cells that could signify higher risk of developing breast cancer.

"Women often consider contralateral prophylactic mastectomy (CPM) not because of medical recommendation, but because they fear having their breast cancer return," said Kelly Hunt.

The clues that may contribute to the right decision are the following: having more than one tumor in the same breast when the initial cancer is diagnosed, having invasive lobular breast cancer, which begins in the milk-producing glands called lobules rather than in the milk ducts, and then invades surrounding tissues, or having a high score in the so-called Gail model that is typically used for patients without breast cancer, but evaluates factors such age, age at menarche, number and findings of previous breast biopsies, age at first live birth and number of first-degree relatives with breast cancer. It has been validated in several studies to calculate the risk of developing an invasive breast cancer over the next five years. The five-year risk of 1.67 percent is traditionally used as the cutoff point for the definition of "high risk.”

However critics of the research, meanwhile, note that women with breast cancer can reduce their risk of re-occurrence with hormones or chemotherapy, and that moreover, there's no evidence that this surgery reduces mortality.

According to the American Cancer society an estimated 1.3 million women are diagnosed with breast cancer per year. Women in the United States have the highest incidence rates of breast cancer in the world; 141 among white women and 122 among African American women