ATLANTA, Georgia (CNN) — An increasing number of women in the last decade have been deciding to have both their breasts removed after being diagnosed with cancer in a single breast. It now seems that more men are also opting to have this type of double mastectomy, according to a study.

Researchers examined data from national cancer registries of more than 6,000 men who underwent surgery for breast cancer from 2004 to 2011. Most of the men (76 percent) had a single mastectomy, or surgical removal of only the breast with cancer, whereas another 20 percent had lumpectomy, or surgery to remove only the tumor.

Although a small proportion of the men had a double mastectomy, the researchers found the number is on the rise, from 3 percent in 2004 to 5.6 percent in 2011.

"This is not good news because there is no evidence for the benefit of the procedure in terms of survival and there is harm associated with it," said Ahmedin Jemal, vice president of the Surveillance and Health Services Research Program at the American Cancer Society and lead author of the study, which was published on Tuesday in the journal JAMA Surgery.

For some women there is benefit associated with having a double mastectomy, but only for those who have a genetic mutation, such as BRCA1 or BRCA2, which increases the risk of developing cancer in the second breast. Studies have found that the procedure can substantially increase life expectancy for these women, but it provides little survival benefit among women who do not have a genetic risk factor.

But even among men who have a BRCA1 or BRCA2 mutation, there has not been enough research looking at whether a double mastectomy can improve life expectancy, said Dr. Todd M. Tuttle, chief of surgical oncology at the University of Minnesota. Tuttle was involved in a study that found little benefit of a double mastectomy for women without genetic risk factors, but he did not participate in the current research.

Although it is not clear whether certain men could benefit from the procedure, there is probably not very high risk associated with it either. Whereas women often have reconstructive surgery, which is associated with infection and bleeding, men do not typically have reconstructive surgery, and thus do not face the resulting complications, Tuttle said.

The current study did not look at reasons behind men's decision to have both their breasts removed, but "factors like fear and anxiety of developing a secondary cancer definitely play a role," Jemal said.

The increase in genetic testing probably also plays a role in more double mastectomies among both men and women, Jemal said. However, it does not seem these tests are necessarily keeping people without genetic risk factors from having the procedure. Even though only about 5 percent to 10 percent of people with breast cancer have BRCA1 and BRCA2 mutations, the current study found that 16.5 percent of men age 20 to 39 had a double mastectomy, Jemal said. (The procedure was less common in older men.)

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Fear of getting breast cancer again, rather than their actual risk based on genetic mutations and other factors, could be contributing to the increase in double mastectomy rates among women as well, Tuttle said. "I think most women who undergo a [double mastectomy] don't have a markedly elevated risk of developing cancer in their opposite breast," he said.

A recent study found that the number of women with breast cancer who are candidates for a lumpectomy but instead opt to have a double mastectomy has climbed from 2 percent in 1998 to 11.2 percent in 2011.

There has also been an increase in women getting a double mastectomy even though they have not been diagnosed with breast cancer, such as the high-profile story of Angelina Jolie. In these cases, the procedure can offer survival benefits for women who are at increased risk of breast cancer based on genetic mutations and family history, Tuttle said. "[Jolie] did everything right," he added.

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