Published December 3, 2012 By Dr. Susan Love

Lots of medical meetings are held at this time of year, which means lots of media coverage of new breast cancer research. Whenever you hear about a new study, keep in mind that any results that are presented but not published have not passed the critical peer review process and are considered preliminary.

This will undoubtedly be the case with many of the stories coming out of the 2012 San Antonio Breast Cancer Symposium which begins tomorrow. I won’t be attending this year, as I am still recovering from my transplant. But I will be using my blog to keep you abreast (pun intended) of what emerges from the meeting and help you separate the important news from the hype.

Right now, I want to address two recent studies that illustrate women’s concerns about their other, healthy breast after a cancer diagnosis. One study looked at the risk of getting breast cancer in the other breast; the other explored women’s understanding of the benefits of a contralateral mastectomy.

The first study, about breast cancer risk, was presented in September at the American Society of Clinical Oncology Breast Cancer Symposium by Courtney Vito, a surgical oncologist at City of Hope in Duarte, Calif. Vito and her research team used a Surveillance, Epidemiology and End Results (SEER) database to look at second cancers that occurred in 109,411 women who had been diagnosed with breast cancer in one breast between 1998 and 2006. All of the patients had a mastectomy, with 10 percent also choosing to have a contralateral prophylactic mastectomy (preventative removal of the healthy breast).

The standard teaching has been that the risk of a second breast cancer is 1 percent per year. But Vito’s study found that the risk of a second breast cancer is actually lower: less than 1 percent over 51 months (four years). Specifically, a second cancer was diagnosed in only 867 women, the majority of whom (66.2%) had their cancer detected at an early stage. The women with the highest risk of developing a cancer in the opposite breast were those who were known to have a BRCA1 or BRCA2 genetic mutation

Why is the risk of a second cancer even lower than we had believed? It may be, in part, because many of the drugs used to treat the first cancer—hormonal therapies and even chemotherapy—can reduce the risk of cancer occurring in the other breast. There also could be other factors that weren’t properly accounted for previously. What is clear is that we need to look more closely at the increasingly widespread use of contralateral prophylactic mastectomy—especially since the risk of complications from this surgery can be as high as 20 percent.

Why do women choose to have a double mastectomy? The second study, which was presented at the Quality Care Symposium in November by Sarah T. Hawley, an associate professor of general medicine at the University of Michigan in Ann Arbor, explored this exact question. She found that 90 percent of women with early stage breast cancer underwent the surgery because they were “very worried” about recurrence.

Some of these women may have been very worried because their risk of recurrence was not explained clearly. A woman’s prognosis is determined by the original cancer—its molecular type and its likelihood to spread to another organs—and how it is treated. Getting a second cancer in the other breast is unlikely to change this outcome. It’s also likely that after their first experience some of these women didn’t want to continue to  have mammograms and MRI’s and preferred to have their healthy breast removed.  In addition, plastic surgeons prefer doing a bilateral mastectomy because it makes it easier to do reconstruction, so that could have played into their decision.

I would never argue with any women about her personal choice. However, I do think it is important for us to realize that it is not what occurs in the breast that causes women to die of breast cancer but rather what happens when the cancer cells spread to other parts of the body. And from that perspective, it’s the systemic therapy, such as chemotherapy, hormone therapy, and Herceptin, that has been found to improve survival—much more than having the other breast removed.

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