Getting A Double Mastectomy Doesn’t Increase Breast Cancer Survival Rate, New Study Finds

Many women who are diagnosed with breast cancer in one breast opt for a double mastectomy in hopes of preventing the cancer from spreading to the other breast. However, a new study reveals that doing so doesn’t actually increase survival rates.

The study — published July 25 in JAMA Oncology — analyzed more than 661,000 women diagnosed with cancer in one breast between 2000 and 2019. The cases ranged from ductal carcinoma in situ, a non-invasive stage zero breast cancer, to stage 3 invasive breast cancers.

For women who underwent a lumpectomy or a mastectomy, there was only a 7% chance of developing cancer later in the other breast. Researchers also found that removing the other breast with a double mastectomy does not provide any survival advantage.

Over the 20 years studied, deaths from breast cancer were similar in all groups, with 8.5% of women who had lumpectomies, 9% of women who had mastectomies, and 8.5% of women who had double mastectomies. 

“That seems like a paradox,” said lead author Dr. Steven Narod, breast cancer researcher and physician at Women’s College Hospital in Toronto. “If you get a contralateral breast cancer, your risk of dying goes up. But preventing it doesn’t improve your survival.”

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Narod said that the study raises key questions about contralateral breast cancers — an invasive second breast cancer that develops in the opposite breast more than six months after the first cancer is diagnosed — and how breast cancer spreads.

Additionally, the study notes that these results may not apply to those who test positive for the BRCA gene, which puts them at greater risk. According to the CDC, one in every 500 women in the United States has a gene variant. In these cases, researchers — and the American Cancer Society — state that double mastectomies done as a preventative surgery is worth considering.

One in eight women in the United States are diagnosed with breast cancer, and mammograms are vital for early detection.

In May 2023, the U.S. Preventive Services Task Force lowered the recommended age for screening for breast cancer after an increase in younger diagnoses. The task force stated that science now shows all women should start getting screened every other year at age 40, which could result in 19% more lives being saved.

In addition to staying on top of routine screenings, health officials advise women of all ages to practice "breast self-awareness," which means becoming familiar with how a person's own breasts normally look and feel, so they will be more likely to recognize anything out of the ordinary when doing a breast self-examination.

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