An increasing number of women with cancer in one breast are choosing to have both breasts surgically removed in hopes of reducing the chance of developing cancer in the unaffected breast. But does this approach—called bilateral, or double, mastectomy—really improve the odds of survival? A new NIH-funded study indicates that, for the vast majority of women, it does not .
A research team led by Allison Kurian, an oncologist at Stanford University School of Medicine, and Scarlett Gomez, an epidemiologist at the Cancer Prevention Institute of California in Fremont, used the California Cancer Registry to study the 10-year survival outcomes of patients diagnosed with early-stage cancer (stages 0–III) in one breast, between 1998 and 2011.
In this observational study, the researchers compared the outcomes of almost 190,000 women who chose one of three treatment options. The first is a lumpectomy, in which the surgeon removes the cancerous tumor and surrounding tissue, but preserves the rest of the breast. This is followed by radiation treatments. The second option is a unilateral, or single, mastectomy, in which the entire breast is removed. The third approach is bilateral, or double, mastectomy, which removes both affected and unaffected breasts.
The researchers documented that among women with early-stage breast cancer in this study, the rate of bilateral mastectomy jumped from 2 percent in 1998 to 12.3 percent in 2011. Among breast cancer patients age 40 and younger, that trend was even more dramatic, soaring from 3.6 percent in 1998 to 33 percent in 2011. The women most likely to choose double mastectomy were non-Hispanic whites of higher socioeconomic status with private health insurance.
It isn’t clear exactly what prompted this upsurge in double mastectomy, which is more expensive, risky, and prone to complications than other two surgical approaches. But Kurian and Gomez suggest that when faced with a potentially life-threatening diagnosis of cancer in one breast—and fears about possibly developing cancer in the other—women may assume that the most aggressive surgery is the best. The researchers also said it’s also possible that new plastic surgery techniques that achieve breast symmetry through bilateral reconstruction may make double mastectomy more appealing to some women.
Despite its recent upsurge in popularity, the study found double mastectomy conferred no survival advantage over the less aggressive approach of lumpectomy followed by radiation. These findings should prove very helpful to women and their doctors as they weigh the various options available for treating early-stage breast cancer.
It’s important to note that previous research has identified a small subset of women for whom a double mastectomy does appear to confer a survival benefit: the roughly 5 percent of breast cancer patients with germline mutations in the BRCA1 or BRCA2 genes . If such women develop cancer in one breast, they face a high risk of developing cancer in the opposite breast—as well as a high risk of ovarian cancer.
Interestingly, the new study found breast cancer survival rates to be slightly worse among women in the unilateral mastectomy group than in the lumpectomy/radiation and bilateral mastectomy groups. However, researchers said that difference probably was not due to the treatment itself, but more likely was related to the fact that unilateral mastectomies were more often performed on minority women of lower economic status who were treated at medical facilities that serve poorer patients. This situation, thus, represents yet another example of a health disparity and is an important area for further research to identify solutions.
 Use of and mortality after bilateral mastectomy compared with other surgical treatments for breast cancer in California, 1998-2011. Kurian AW, Lichtensztajn DY, Keegan TH, Nelson DO, Clarke CA, Gomez SL. JAMA. 2014 Sep 3;312(9):902-14.
 Association of risk-reducing surgery in BRCA1 or BRCA2 mutation carriers with cancer risk and mortality. Domchek SM, Friebel TM, Singer CF, Evans DG, Lynch HT, Isaacs C, Garber JE, Neuhausen SL, Matloff E, Eeles R, Pichert G, Van t’veer L, Tung N, Weitzel JN, Couch FJ, Rubinstein WS, Ganz PA, Daly MB, Olopade OI, Tomlinson G, Schildkraut J, Blum JL, Rebbeck TR. JAMA. 2010 Sep 1;304(9):967-75.
Contralateral prophylactic mastectomy: is it a reasonable option? Newman LA. JAMA. 2014 Sep 3;312(9):895-7.
Scarlett Gomez, Cancer Prevention Institute of California
Allison Kurian, Stanford University Medical School
NIH support: National Cancer Institute