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Women diagnosed with invasive breast cancer have a number of surgical options. They can have breast-conserving surgery (lumpectomy) with radiation, a unilateral (single) mastectomy to remove only the tissue from the cancerous breast, or a contralateral prophylactic mastectomy (CPM), which removes both breasts. A new study finds that more women are opting for CPM, yet overall survival for these patients is not increasing. (5/3/2016)
Whether invasive breast cancer patients who elect to have contralateral prophylactic mastectomy (risk-reducing removal of a woman’s healthy breast when her opposite breast has breast cancer) have increased survival compared to women who have breast-conserving surgery (lumpectomy) with radiation or mastectomy only in the treated breast.
Why is this study important? Contralateral prophylactic mastectomy is an invasive surgical procedure that puts women at risk for complications such as infection. After diagnosis, some women are at high risk for a second breast cancer due to an inherited mutation in BRCA or another gene that increases breast cancer risk. However, according to the study authors, “the majority of women undergoing CPM are at low risk for developing a contralateral breast cancer.” Study authors reasoned that women who already have a low risk for a second breast cancer are unlikely to see a survival benefit by removing their healthy breast.
This study suggests that more women with invasive breast cancer are currently opting for CPM, even though for them, this surgery does not improve survival. However, this result is specific to a very general population. Other research has shown that CPM does reduce the chance of a second breast cancer in women with BRCA, other cancer-causing mutations, or a strong family history of 2 or more first-degree relatives with breast or ovarian cancer. Additionally, in this study, researchers focused on survival, but women also choose CPM for other reasons. Women with invasive breast cancer should discuss with their health care provider which procedure is best for them.
Women with genetic mutations in BRCA and other genes associated with increased cancer risk, and women with a strong family history of breast or ovarian cancer benefit from contralateral prophylactic mastectomy (CPM) because they have a higher risk for a second breast cancer. However, these women represent less than one-third of women who choose CPM. Studies show that about 80%-98% of women who choose CPM do so because they want to prevent cancer in their other breast, yet the majority of women who choose CPM are at low risk of developing a second breast cancer.
In March 2016, Stephanie Wong and colleagues from the Harvard School of Public Health and other institutions published a study in Annals of Surgery that looked at the increasing rate of CPM, and assessed if it correlated to an improvement in survival.
Do increases in contralateral prophylactic mastectomy rates in women with invasive breast cancer result in longer survival for these patients?
This study used data from the SEER (Surveillance, Epidemiology, and End Results) database, including 494,488 women who had stages 1, 2 or 3 unilateral breast cancer and were diagnosed between 1998 and 2012.
This study used previously collected information from women through the SEER database—research using databases such as SEER is useful in designing controlled studies, which compare how different treatment options affect survival. Because the researchers did not collect the data themselves, they did not have all information about these women, such as their risk factors (genetic information, family history, other medical issues), socioeconomic status, or other potentially pertinent factors. The researchers also did not know the HER2 receptor status of these patients (positive or negative), procedure preference of their surgeons, or what treatments these women had.
This study suggests that in general, CPM provides no survival benefit in most women with invasive breast cancer. Additionally, a study done by Alison Kurian and colleagues from Stanford University and other institutions found similar results in Californian women, where “use of bilateral mastectomy increased significantly throughout California from 1998 through 2011, and was not associated with lower mortality than that achieved with breast-conserving surgery plus radiation.” However, they did find that women who underwent unilateral mastectomy had higher mortality than women who underwent bilateral mastectomy or breast-conserving surgery plus radiation.
It is important to remember that there are groups of women—carriers of BRCA or other mutations and women with a strong family history of breast cancer—who do see a survival benefit from CPM. Women have different reasons for choosing or not choosing CPM; survival is one reason but other reasons are equally valid. Ultimately, women should speak with their health care provider to make sure they understand the risks and benefits of CPM, and to determine what plan of action is most appropriate for them.
Posted May 3, 2016
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Giuliano AE, Boolbol S, Degnim A, et al. “Society of Surgical Oncology: position statement on prophylactic mastectomy. Approved by the Society of Surgical Oncology Executive.” Ann Surg Oncol. March 2007; 14: 2425-2427.
Kurian AW, Lichtensztajn DY, Keegan THM, et al. “Use of and mortality after bilateral mastectomy compared with other surgical treatments for breast cancer in California, 1998-2011.” JAMA. 2014; 212(9): 902-914.
Morrow M. “Prophylactic mastectomy of the contralateral breast.” Breast. 2011; 20 (suppl 2): S108-S110.
Wong SM, Freedman RA, Sagara Y, et al. “Growing Use of Contralateral Prophylactic Mastectomy Despite No Improvement in Long-term Survival for Invasive Breast Cancer.” Annals of Surgery. Published online first on March 8, 2016.
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