Many patients with breast cancer who have their second breast removed as a precaution don't actually need the double mastectomy, a new study finds.

Researchers who evaluated more than 1,400 women with breast cancer found that nearly 7 out of 10 who underwent preventive removal of their healthy breast were not at high risk of cancer in the unaffected breast, the Newsmax Health reported.

"What we found is that almost 70 percent did not have a clinical indication for it," said study researcher Sarah Hawley, an associate professor of internal medicine at the University of Michigan, Ann Arbor. The researchers defined a clinical indication as having the genetic mutation BRCA 1 or 2 or a strong family history of breast cancer, both of which raise breast cancer risk.

The dual procedure -- known as contralateral prophylactic mastectomy -- has increased markedly in recent years, even though experts suggest it only be considered in these high-risk cases.

Hawley's team evaluated 1,447 women who had been treated for breast cancer but had not had a recurrence.  Nearly 19 percent said they strongly considered having the opposite unaffected breast removed, and about 8 percent actually had the procedure.

However, about 69 percent of those who had the double mastectomy had no major genetic or family risk factors for getting cancer in the other breast, Hawley found.

She advises women to put the risk in perspective, which is not always easy. "The average risk of a new primary cancer in the opposite breast is about 2.5 percent over five years," she said. That risk can be halved with use of hormonal drugs, she added.

For women with risky genetic mutations, the likelihood of a new primary cancer in the opposite breast is 20 percent over the next five years, she said.