SAN ANTONIO – The worldwide upsurge in bilateral mastectomy for unilateral breast cancer in the last decade came under withering fire from prominent breast surgeons at the San Antonio Breast Cancer Symposium.
“It seems crazy, doesn’t it, that we’re spending all this time trying to conserve the breast, yet we’re facing a tsunami of requests for bilateral mastectomy,” observed Dr. Fiona MacNeill, chairman of the education and training committee of the Royal College of Surgeons of England.
“A contralateral risk–reducing prophylactic mastectomy undoubtedly will reduce the risk of contralateral breast cancer, since you’re removing the breast, but this is overtreatment for the vast majority of women who request it. At 20 years we haven’t been able to demonstrate that it offers a significant survival advantage. I think a lot of what’s driving bilateral mastectomy is fear and ignorance, a failure to understand risk by patients and often by health professionals,” said Dr. MacNeill, a breast surgeon at Royal Marsden Hospital in London.
In an invited special lecture titled, “Less is more: minimizing breast cancer surgery,” Dr. MacNeill began by observing, “Only a surgeon could give this talk, because only a surgeon can tell you why we’re doing too much surgery.”
She stressed three main points: surgery is, as she put it, “a medieval treatment in a molecular era.” Overwhelming evidence shows that breast cancer outcomes are determined by disease biology, burden, and response to systemic therapy and not by the extent of surgery. And since there is no survival benefit for more aggressive surgery, the surgeon’s goal must be to optimize breast and axillary conservation.
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Dr. Ismail Jatoi
In a separate presentation, Dr. Ismail Jatoi, professor and chief of surgical oncology at the University of Texas, San Antonio, outlined trends in surgical treatment of early-stage breast cancer as documented in a recent major retrospective study conducted in Tennessee of 1.2 million women treated at accredited U.S. breast cancer centers during 1998-2011.
The Tennessee investigators’ analysis points to a polarization in surgical therapy: The rate of unilateral mastectomy without reconstruction has dropped steadily since the beginning of the study period in 1998 among women eligible for breast-conserving surgery (BCS), while starting around 2006 the rate of bilateral mastectomy with reconstruction has surged. This increase in bilateral mastectomies with reconstruction resulted in an adjusted 34% jump in the overall mastectomy rate during 2004-2011 as compared with 1998-2003. As a result, in 2011 nearly 40% of women with early breast cancer underwent mastectomy. Meanwhile, the rate of BCS has been waning since 2006 (JAMA Surg. 2015 Jan;150[1]:9-16).
These disturbing trends have been fueled in part by at least eight published observational studies reporting improved survival with contralateral prophylactic mastectomy (CPM) as compared with unilateral mastectomy or BCS. But these were all observational studies and hence likely compromised by unmeasured confounders, according to Dr. Jatoi.
He presented highlights of his study of National Cancer Institute Surveillance, Epidemiology, and End Results data to support his recommendation that these observational studies be taken with a grain of salt.
His study included nearly 26,000 women who underwent CPM and more than 400,000 who did not. In a multivariate regression analysis adjusted for age, race, tumor stage, hormone receptor status, and histologic grade, CPM was associated with a statistically significant and impressive-sounding 16% reduction in the 5-year risk of breast cancer–specific mortality, a 17% reduction in overall mortality, and … a highly improbable 29% reduction in noncancer mortality (Breast Cancer Res Treat. 2014 Nov;148[2]:389-96).
“Obviously bilateral mastectomy is not going to reduce your risk of dying of heart attack or stroke or other noncancer causes. So even though we adjusted for everything possible in the SEER database, it suggests there were still unmeasured confounders. What this study shows is that it’s these unmeasured confounders that pose a threat to the validity of observational studies,” the surgeon said.
“Randomized data and observational studies consistently show that breast-conserving surgery is the optimal choice for most patients. It’s the safest choice, it’s cost effective, and it should remain in 2015 the optimal treatment for breast cancer,” he declared.
The cost-effectiveness of BCS was underscored during the symposium by means of a retrospective study presented by Dr. Benjamin D. Smith.
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Dr. Benjamin D. Smith
He and his coinvestigators analyzed costs and complication rates in the first 2 years following diagnosis of early-stage breast cancer in 44,344 patients under age 65 in the MarketScan database and almost 61,000 older women in the SEER-Medicare database.