Some women diagnosed with early-stage breast cancer in one breast choose to have both breasts removed. Removing the healthy breast is called "contralateral prophylactic mastectomy." In most cases, the healthy breast is removed because a woman has many risk factors for breast cancer or understandable fears that a new, second breast cancer might develop in the healthy breast.
The large study reviewed here found that women diagnosed with early-stage breast cancer who chose to have contralateral prophylactic mastectomy were 16% less likely to die from breast cancer in the 4 years after diagnosis than women who didn't have the healthy breast removed. Still, it's unclear if removing the healthy breast is the reason for the better survival.
Women diagnosed with early-stage breast cancer in one breast have a higher-than-average risk of developing a new, second cancer in the other breast. This risk is very high for some women and only a little higher than average for other women. Factors that can increase this risk are being diagnosed with hormone-receptor-negative breast cancer and testing positive for the BRCA1 or BRCA2 genes.
If the risk of a new cancer in the opposite breast is very high, doctors may recommend contralateral prophylactic mastectomy. Even if their doctor doesn't recommend removing the opposite breast, some women choose contralateral prophylactic mastectomy because they're understandably afraid of developing another breast cancer. Some women also may ask for contralateral prophylactic mastectomy to have more balanced cosmetic results after reconstructive surgery on both breasts.
This study looked at the outcomes of more than 107,000 women diagnosed with early-stage breast cancer who had mastectomy as part of their treatment. About 8,900 of those women also chose to have contralateral prophylactic mastectomy. All of the women were followed for about 4 years so the researchers could compare the outcomes of the women who had contralateral prophylactic mastectomy to women who didn't.
Overall, women who had contralateral prophylactic mastectomy were 16% less likely to have died from breast cancer, compared women who didn't have the opposite breast removed:
It's important to know that most of the women were alive 4 years after surgery, whether or not they had contralateral prophylactic mastectomy.
The researchers aren't sure whether the link between contralateral prophylactic mastectomy and better survival is related to removing the healthy breast or to other health/breast cancer factors or treatment choices -- such as getting chemotherapy after surgery.
Other doctors who looked at the study results noticed that women younger than 50 diagnosed with hormone-receptor-negative breast cancer were a large portion of the group that chose to have contralateral prophylactic mastectomy and had better survival. These doctors said that removing the opposite breast might not have the same benefits for older women diagnosed with hormone-receptor-positive breast cancer.
Women younger than 50 diagnosed with hormone-receptor-negative breast cancer have a higher risk of the cancer coming back (recurrence) and of developing a new cancer in the future compared to older women diagnosed with hormone-receptor-positive breast cancer. So it makes sense that contralateral prophylactic mastectomy might improve survival in some younger women diagnosed with early-stage, hormone-receptor-negative breast cancer.
In January 2009, Breastcancer.org reviewed an earlier study looking at the benefits of contralateral prophylactic mastectomy. That study found that women with a specific breast cancer risk profile and/or one of three specific breast cancer characteristics got the most benefit from removing the opposite breast:Women with one of these three factors were more than 3 times more likely than women who had none of the factors to develop breast cancer in the opposite breast. So the results suggested that contralateral prophylactic mastectomy makes the most sense for women with any of the factors.
If you've been diagnosed with early-stage breast cancer, ask your doctor about ALL your treatment and risk reduction options. Prophylactic mastectomy is only one of these options and it's a very aggressive step. It may be the right decision for you, but do talk to your doctor to make sure that your decisions are based on your actual risk and not only fear. Ask about your Gail score and how the information in your pathology report may affect your future risk. If you're not completely sure about removing the opposite breast, waiting to decide until after your breast cancer treatment plan is complete could be a good idea. Together, you and your doctor can make the decisions that are best for you and your unique situation.
Women with breast cancer had better overall survival if they underwent contralateral prophylactic mastectomy (CPM), although whether the procedure was responsible is unclear, researchers said.
In a multivariate analysis, controlling for tumor stage and grade and other risk factors, CPM was associated with a hazard ratio for death of 0.84 (95% CI 0.76 to 0.92) among more than 107,000 women undergoing therapeutic mastectomy in the Surveillance, Epidemiology and End Results database, according to an online report in the Journal of the National Cancer Institute.
The survival gain in the analysis, which had a median follow-up of 47 months after surgery, was most pronounced for younger women with early-stage, estrogen receptor-negative breast tumors, according to Isabelle Bedrosian, MD, of M.D. Anderson Cancer Center in Houston, and colleagues.
However, the nature of the study prevented the researchers from concluding for sure that the procedure itself was responsible for the survival gain.
They wrote that they had accounted "for as many potential influences on outcomes as possible within the available data, and the results are internally consistent across a number of different approaches to the data, which suggest robustness of our findings. However, despite these efforts, a causal relationship between survival and CPM cannot be proved, that is only possible in a randomized controlled trial, unlikely to be completed in the foreseeable future."
Other oncologists contacted by MedPage Today and ABC News were divided as to whether the prophylactic procedure is likely to improve survival, or is really a proxy for some other factor associated with better outcomes.
George Sledge Jr., MD, of Indiana University in Indianapolis, told MedPage Today in an e-mail that selection bias was probably responsible for the finding. He noted that contralateral prophylactic mastectomy was also associated with lower noncancer mortality for some patient groups in the study.
"The simplest explanation is what happened with similar retrospective analyses of estrogen replacement therapy in postmenopausal women: the women getting postmenopausal estrogens as a group had better general health practices, were more upper-income, had more interactions with the medical system, etc.," according to Sledge.
Lisa Carey, MD, of the University of North Carolina in Chapel Hill, questioned whether a survival benefit attributable to CPM could be detected with median follow-up of less than four years.
"[It] suggests that the investigators are measuring another prognostic variable related to the existing cancer that also varied between CPM yes/no decision-making," she wrote in an e-mail. "In that sense, the CPM is a proxy for a prognostic factor that differs in the two groups, but is not causal."
But Victor Vogel, MD, national vice president for research at the American Cancer Society, said the benefit is probably real for women under 50 with ER-negative disease.
"My fear is that clinicians would now begin to recommend contralateral mastectomy to the majority of breast cancer patients (those older than 60 years) when there is very little advantage to those women," he added in an e-mail. "In my opinion, any women requesting a contralateral prophylactic mastectomy should wait one year before having the procedure done. Many women who do it immediately express regret a year or two after the procedure."
The analysis by Bedrosian and colleagues covered SEER data available in 2008 for women undergoing total or modified radical mastectomy for unilateral breast cancer from 1998 to 2003, a total of 107,106 patients.
The findings extend an earlier analysis of SEER data by the same researchers that also found improved survival with CPM, primarily in younger patients with less advanced, ER-negative disease.
Univariate statistics in the new study showed disease-specific survival was 37% lower in patients undergoing CPM at or near the time of therapeutic mastectomy (HR 0.63, 95% CI 0.57 to 0.69).
A risk-stratified analysis indicated that most of this association was attributable to reduced breast cancer-specific mortality in women under 50 with ER-negative tumors at stages I or II (HR 0.68, 95% CI 0.53 to 0.88).
Five-year adjusted breast cancer survival rates for these women was improved by just under five percentage points (88.5% versus 83.7%), Bedrosian and colleagues found.
The study was subject to some important limitations, including the lack of SEER data on potential confounding factors such as BRCA mutation status, family history, and chemotherapy, which might affect the risk of metastatic or recurrent cancer as well as decisions to seek CPM.
Also, the researchers excluded some 165,000 breast cancer patients in the SEER database because they had undergone mastectomies or other procedures other than total or modified radical procedures.
The study was supported by the American Society of Clinical Oncology.
No potential conflicts of interest were reported.
This article was developed in collaboration with ABC News.Primary source: Journal of the National Cancer Institute Source reference: Bedrosian I, et al "Population-based study of contralateral prophylactic mastectomy and survival outcomes of breast cancer patients" J Natl Cancer Inst 2010; DOI: 10.1093/jnci/djq018.
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