STANFORD, CALIFORNIA. A study just published in JAMA examined the important question of the comparative mortality associated with bilateral mastectomy compared with unilateral mastectomy or breast conserving surgery plus radiation, the latter commonly referred to as a lumpectomy with radiation. The study population consisted of all female California residents newly diagnosed with a first primary breast cancer from 1998 to 2011 and numbered almost 190,000.

When breast-conserving surgery with radiation was used as the reference, mortality over the study period of 15 years associated with bilateral mastectomy did not significantly differ from the reference treatment in a statistical analysis that corrected for a large number of confounding factors. The same comparison with unilateral mastectomy yielded evidence of enhanced risk for this traditional procedure.

According to the authors, this observational study is the first to compare the three surgical procedures side by side. The authors cited other studies that also found enhanced mortality of unilateral mastectomy compared to breast conserving surgery. However, there are no randomized trial data to inform concerning the question of whether or not the bilateral mastectomy improves survival, and the authors suggest it is unlikely that such a trial will ever be performed. Thus one must rely on observational data corrected for multiple confounders.

This study also examined the increase over time in the use of the bilateral mastectomy. Over the period in question, the rate increased from 2% to over 12%. They mention proposed explanations including the increased use of highly sensitive MRI imaging, increased anxiety driving the desire for preventive surgery, and the increase in genetic testing which facilitates the identification of high-risk patients. High profile celebrity endorsements, which increased general awareness of the bilateral procedure, occurred after the end of this study. The authors also remark that patient satisfaction after bilateral mastectomy is variable with noteworthy areas of concern over deleterious effects, reconstruction failures and infections.

Kurian AW, Lichtensztajn DY, Keegan TH, Nelson DO, Clarke CA, Gomez SL. Use of and mortality after bilateral mastectomy compared with other surgical treatments for breast cancer in California, 1998-2011. JAMA. 2014;312:902-914