Recent research published in the Journal of the National Cancer Institute, titled “Survival Outcomes After Contralateral Prophylactic Mastectomy: A Decision Analysis”, has demonstrated that, even though the incidences of contralateral prophylactic mastectomies (CPM) in women suffering from breast cancer in only one breast has increased in the U.S., it only adds a marginal life expectancy benefit, depending on the type and stage of cancer.
CPM consists of a double mastectomy in which the healthy breast is removed alongside the cancerous one, to reduce the risk of recurrence. As such, breast cancer patients report that the main reason they choose CPM is out of concern they will develop contralateral breast cancer.
Using data from the Surveillance, Epidemiology, and End Results (SEER) registry, lead author Pamela R. Portschy, of the Department of Surgery, University of Minnesota, Minneapolis, and colleagues, designed a model simulating survival outcomes for women with stage I or II breast cancer receiving or not CPM.
Survival benefit estimates were created for women according to age, breast cancer stage and estrogen receptor status. Importantly, women who carried BRCA mutations were excluded from the analysis, since this type of breast cancer has an increased risk for the development of contralateral breast cancer.
The results demonstrated that undergoing CPM resulted in an average gain in life expectancy of 0.13 to 0.59 years for women with stage I breast cancer and from 0.08 to 0.29 years for women with stage II breast cancer.
Furthermore, younger women and those with stage I and Estrogen Receptor (ER)-negative breast cancer had a greater benefit when undergoing CPM.
The authors also found that the 20-year disease-free survival benefit oscillated between 4.25% to 7.20% for women with stage I breast cancer and between 2.73% to 4.62% for women with stage II breast cancer, with values depending on the patient’s age and ER status of the tumor.
The authors conclude in their study that “Survival is only one potential benefit of a cancer risk-reduction strategy; effects on cancer-related anxiety, cosmesis, and self-image are also important in decision-making processes. Survival estimates derived from our model may be useful for physicians and breast cancer patients to arrive at evidence-based informed decisions regarding CPM. The balance between harm and benefit depends on the patient’s preferences and highlights the importance of capturing the patient’s values and expectations before considering CPM”.