Study: More patients with invasive breast cancer opting for double mastectomies

IN DEPTH REVIEW OF RESEARCH

Study background:

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.

Researchers of this study wanted to know:  

Do increases in contralateral prophylactic mastectomy rates in women with invasive breast cancer result in longer survival for these patients?

Population(s) looked at in the study:

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.

Study Findings:

1. The number of women with invasive breast cancer who chose contralateral prophylactic mastectomy (CPM) between 2002 and 2012 significantly increased, from about 4% in 2002 to about 13% in 2012.
2. The increase in breast reconstruction after CPM also increased, from about 35% in 2002 and to about 55% in 2012.
3. No significant improvement in estimated breast cancer-specific survival or overall survival was identified between women who had CPM compared to women who had breast-conservation (lumpectomy) with radiation.
4. Even when HR (hormone receptor) status (positive or negative) and age were factored in, the researchers still did not see any benefit in breast cancer-specific survival or overall survival.

Limitations:

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.

Conclusions:  

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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