Breast cancer survival not boosted by double mastectomy, study says

For the more than 310,000 women diagnosed with breast cancer every year, no matter how well the treatment goes, there is always a lingering fear. Could the disease come back, even years later? And what if it comes back in the other breast? Could they protect themselves today by having a double mastectomy?

A study has concluded that there is no survival advantage to having the other breast removed. Women who had a lumpectomy or a mastectomy and kept their other breast did just as well as women who had a double mastectomy, Dr. Steven Narod of Women’s College Hospital in Toronto and his colleagues reported, using U.S. data from more than 661,000 women with breast cancer on one side.

In the study, published in JAMA Oncology on Thursday, the researchers added that most women did very well; the chance of cancer in the other breast was about 7% over 20 years.

But the study’s results may not apply to women who have a gene variant, BRCA1 or BRCA2, which greatly increases their cancer risk. For the 1 in 500 American women with this variant, cancer researchers agree that it’s worth considering a double mastectomy.

The finding that a double mastectomy is not protective against death for many breast cancers seems counterintuitive, Narod admitted. An accompanying editorial, by Dr. Seema Ahsan Khan, a breast cancer surgeon at Northwestern University, and Masha Kocherginsky, a biostatistician also at Northwestern, called it a conundrum.

Previous smaller studies have come to the same conclusion. But, Narod said, some doctors have questioned the methods in earlier research.

The new paper should reassure women, said Dr. Eric Winer, a breast cancer specialist and director of the Yale Cancer Center. Like previous studies, he said, “it suggests that there is absolutely no difference in survival if you have a lumpectomy, a mastectomy or a double mastectomy.”

The new study, said Dr. Angela DeMichele, a professor of medicine and co-leader of the breast cancer program at the University of Pennsylvania, “provides a rigorous analysis.”

Narod said he and his colleagues addressed the risk of developing cancer in the other breast “very systematically.” They reported that the 7% chance of having a second cancer was consistent no matter how advanced the initial cancer was when it was detected in the first breast. The investigators calculated that 69 out of 1,000 women with cancer in one breast would develop a cancer in their other breast within 20 years.

Such a cancer is a worrisome sign, increasing the risk of death fourfold.

Although women who had a double mastectomy seldom had a second cancer in the small amount of remaining breast tissue, the study was large enough to include those who did, and their mortality risk also increased fourfold.

“What the hell is going on?” Narod asked, noting that it would make sense that if a cancer that arose in the second breast could kill, then “preventing it with a double mastectomy would save lives.” But it didn’t.

He concluded that what killed was the spread of the first cancer to other parts of the body.

DeMichele said she carefully explains to patients that they have a real choice in treatment; they don’t have to have a double mastectomy.

Many women, she said, assume that the more surgery they have, the more likely they are to be cured. So they want both breasts removed.

She tells them that removing the second, healthy breast does not prevent cells from their newly diagnosed cancer from spreading to other organs and to bones.

This article originally appeared in The New York Times.

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