Women considering a mastectomy after being diagnosed with breast cancer often face a difficult decision: whether to remove their healthy breast as well.
A new study should make it easier for some of these women to make up their minds. It concludes that patients with a dangerous mutation in their BRCA1 or BRCA2 gene were able to cut their risk of dying from breast cancer nearly in half by opting to remove both breasts.
The BRCA1 and BRCA2 genes contain instructions for producing tumor suppressor proteins. But certain mutations in these genes prevent those proteins from doing their job. As a result, a woman with one of those mutations is estimated to have a 60 percent to 70 percent chance of developing breast cancer at some point in her life. (For women without these mutations, the average lifetime risk of breast cancer is 12.4 percent, according to the National Cancer Institute.)
Studies have found that in the United States and Canada, about half of women with a BRCA mutation who develop cancer in one breast opt to remove the other breast as well, in a procedure called a contralateral mastectomy.
So a team of investigators from the two countries examined the medical records of 390 women who had been diagnosed with Stage 1 or Stage 2 breast cancer between 1977 and 2009. All of the women had a confirmed high-risk mutation in one of their BRCA genes, or they were from a family that was known to carry the mutation and were presumed to have it too.
Among these 390 patients, 44 decided to remove both breasts at the same time, even though one of the breasts was cancer-free. Among the 346 who initially had a single mastectomy, 137 — or 40 percent — later opted to remove their remaining breast even though it was cancer-free. (The researchers hypothesized that these women didn't remove their second breast right away because didn't yet know that they had a BRCA mutation.)
Over the entire 20-year period of the study, 31 percent of the women who had only a single mastectomy died of breast cancer. However, the women who removed both breasts were 48 percent less likely to die of the disease. The results were published online Tuesday by the British Medical Journal.