Most Double Mastectomies Are Unnecessary, Study Finds

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Angelina Jolie had a double mastectomy to prevent breast cancer, but many women who survive cancer are also opting to remove both breasts Neil Hall/Reuters

Some 70 percent of women who undergo double mastectomies for breast cancer don’t need to have both breasts removed, according to a new University of Michigan Comprehensive Cancer Center study.

Most cases of 235,030 breast cancers diagnosed in the U.S. annually affect one breast. Only 2 to 5 percent of cases occur in both breasts at the same time, according to CNN, and a diagnosis in one breast does not increase the likelihood of cancer in the other. Yet more and more women with a single-breast cancer diagnosis are opting for double mastectomy in the hopes of preventing the spread of the diseases. One study that examined breast cancer surgeries from 1998 to 2003 found that the rate of this preventive procedure had “more than doubled” during the six-year survey period.

While the study released Wednesday dealt specifically with double mastectomies with diagnosed cancer cases, the idea of using this surgery to prevent cancer has become an increasingly prominent topic of conversation. In May 2013, the actress and humanitarian Angelina Jolie wrote in a New York Times op-ed that she had both breasts removed after learning she carried a rare gene that put her at great risk of getting breast cancer. In the piece, Jolie suggested that women might consider genetic testing that would indicate whether they too are carriers.  Because carrying the gene does not necessarily mean that cancer will develop and because testing is “often inconclusive,” the U.S. Preventive Services Task Force recommended in December that most women should not get the genetic test recommended by Jolie. By the time the task force recommendations came out, however, physicians had already reported increased interest in genetic testing, with The Boston Globe even describing the trend as the “Angelina Jolie Effect.”

The University of Michigan research indicates just how prevalent the procedure, called a contralateral prophylactic mastectomy, has become for cancer survivors.

The study authors surveyed 1,447 women who were treated for breast cancer and did not have a recurrence. Of those women, 8 percent had a double mastectomy and 18 percent considered the procedure.  

For women with a family history of breast or ovarian cancer—or the handful of appropriate candidates for genetic testing who do have mutations in their BRCA1 or BRCA2 genes, like Jolie—removing a healthy breast after a cancer diagnosis might be a good idea. But women with that mutation only comprise some 10 percent of all breast cancer cases.

Women without a family history or BRCA mutation are “very unlikely to develop a second cancer in the healthy breast,” according to a statement released about the study.

The researchers found, however, that nearly 70 percent of women undergoing contralateral prophylactic mastectomies “did not have either a family history or positive genetic test.” In fact, many “were candidates for breast-conserving lumpectomy.”

“Women appear to be using worry over cancer recurrence to choose contralateral prophylactic mastectomy,” Sarah Hawley, associate professor of internal medicine at the University of Michigan medical school and lead author of the study, says in a statement.

“For women who do not have a strong family history or a genetic finding, we would argue it's probably not appropriate to get the unaffected breast removed,” she said.

So why are these women doing it?

Worry.

One of “the biggest factors” driving women’s decision to have a contralateral prophylactic mastectomy is “concern about recurrence” despite its statistical improbability, the statement on the study notes.

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