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Breast cancer patients are getting more bilateral mastectomies – but not any survival benefit

woman looking out window2The most common cancer diagnosis you or a woman you love is likely to receive is early stage breast cancer, probably after detection by mammogram. One would think that given the regularity with which it's diagnosed, treatment options for early stage breast cancer would be streamlined. Unfortunately, this isn't the case.  There's a staggeringly large menu of potential surgeries and treatments from which a patient and her doctor must choose, each with their own risks and benefits. Not including all of the different hormone blocking and chemotherapies, patients must pick one of three surgeries, shown here in order of escalating invasiveness and risk of complication:

  • Breast-conserving surgery (removal of the tumor only), followed by radiation
  • Single mastectomy (removal of the entire affected breast and any affected lymph nodes)
  • Bilateral mastectomy (the above plus the the unaffected breast)

One also would assume that the medical evidence base providing the benefits to the risk/benefit equations for each surgery would be large and up-to-date. Surprisingly, it is not. The randomized trials comparing lumpectomy and single mastectomy were conducted 30 years ago, and they showed similar risks of death. There has not been (and probably will never be) a randomized trial comparing bilateral mastectomy to one of the less invasive choices for healthy women. Angelina Jolie and other women positive for the breast cancer genes (BRCA1 and BRCA2) are in a different situation. For these women, clinical studies have observed a survival benefit after prophylactic mastectomy. For the 99 percent of women without mutations in these or other high-risk genes, existing trial data do not speak to current trends.

Even after accounting for [numerous factors], we found no evidence of lower mortality for women who had bilateral mastectomy in comparison to breast-conserving surgery

The complexity of choosing a breast cancer surgery - and how evidence should play into that choice - has been a hot topic in the last two months, after the publication of a large study calculating (based on predictive models) that bilateral mastectomy ultimately provides little to no improvement  in life expectancy as compared to a single mastectomy. Soon thereafter, on the New York Times' opinion page, journalist Peggy Orenstein discussed the emotional reasons why women remove their remaining healthy breast, but firmly labeled bilateral mastectomy as  the wrong approach to breast cancer, saying, "It’s hard to imagine... that someone with a basal cell carcinoma on one ear would needlessly remove the other one 'just in case' or for the sake of 'symmetry'.” Other journalists shared why they chose bilateral mastectomy knowing that it wouldn’t necessarily save their life.

To improve the evidence regarding outcomes after the three surgery types, our team at the Stanford Cancer Institute and the Cancer Prevention Institute of California used one of the largest cancer databases available: the cancer registry for the entire state of California. We tracked all 189,734 women diagnosed with stages 0-III breast cancer from 1998-2011 to learn which surgeries they were undergoing for breast cancer treatment and how long they survived afterwards.  These are all women who should have been eligible for breast conserving surgery with radiation. Our results were published today in the Journal of the American Medical Association today and have already received media attention.

We found that bilateral mastectomy for early stage breast cancer increased from 2 percent in 1988 to more than 12 percent in 2011.  The rate of increase was fastest among women younger than age 40 at diagnosis, among whom over one-third of those diagnosed in 2011 had a bilateral mastectomy. Bilateral mastectomy was more often chosen by non-Hispanic white women, those with private insurance, and those who received care at a National Cancer Institute-designated cancer center; while unilateral mastectomy was more often chosen by non-white women and those with public/Medicaid insurance. Even after accounting for characteristics of the women themselves, their tumor types, and their hospitals, we found no evidence of lower mortality for women who had bilateral mastectomy in comparison to breast-conserving surgery. Surprisingly, we found that women who underwent unilateral mastectomy had higher mortality than those who had the other two surgery types. We concluded that despite the growing popularity of bilateral mastectomy, it likely does not provide a better outcome than a less invasive procedure.

These data and the public response to them underscore the need for more updated and more personalized information regarding outcomes after common surgeries. Ideally, these would be accessible real-time by patients and their doctors in easily-understood formats.

Christina A. Clarke, PhD, is a Research Scientist and Scientific Communications Advisor for the Cancer Prevention Institute of California, and a member of the Stanford Cancer Institute.

Previously: At Stanford event, cancer advocate Susan Love talks about “a future with no breast cancer”, Exploring the reasons behind choosing a double mastectomy and Researchers unsure why some breast cancer patients choose double mastectomies
Photo by Alex

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