September 22, 2014
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Use of bilateral mastectomy increased significantly despite lack of mortality benefit

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The use of bilateral mastectomy among women with early-stage breast cancer increased significantly since the late 1990s, but the procedure did reduce mortality compared with breast-conserving surgery plus radiation, according to results of an observational cohort study.

Women who underwent unilateral mastectomy demonstrated higher mortality risks than those who underwent bilateral mastectomy, as well as those who underwent breast-conserving surgery plus radiation, results showed.

Despite the potential medical and psychosocial complications associated with bilateral mastectomy, the procedure has become increasingly common among patients who have unilateral breast cancer, according to background information in the study.

Allison W. Kurian, MD, MSc, of the department of medicine at Stanford University School of Medicine, and colleagues sought to compare the use of bilateral mastectomy, unilateral mastectomy, and breast-conserving therapy with radiation. They also assessed post-treatment mortality for each treatment option.

The analysis included 189,734 women in the California Cancer Registry. All women were diagnosed with stage 0 to stage III unilateral breast cancer between 1998 and 2011.

Median follow-up was 89.1 months.

Usage of bilateral mastectomy increased from 2% (95% CI, 1.7-2.2) in 1998 to 12.3% (95% CI, 11.8-12.9) in 2011. This corresponded to an annual increase of 14.3% (95% CI, 13.1-15.5).

Researchers observed a particularly dramatic increase among women aged younger than 40 years. In that population, usage of bilateral mastectomy increased from 3.65% (95% CI, 2.3-5) in 1998 to 33% (95% CI, 29.8-36.5) in 2011.

Women who had private insurance and those who were non-Hispanic white more often elected to undergo bilateral mastectomy. Women who received care at an NCI-designated cancer center were more likely to undergo bilateral mastectomy than those who sought care at non-NCI cancer centers (OR=1.13; 95% CI, 1.04-1.22).

Women who were Filipina (OR=2; 95% CI, 1.9-2.11) or Hispanic (OR=1.16; 95% CI, 1.13-1.2) were more likely than non-Hispanic whites to undergo unilateral mastectomy. Those with Medicaid or public insurance also were more likely than those with private insurance to opt for unilateral mastectomy (OR=1.08; 95% CI, 1.05-1.11).

Researchers determined unilateral mastectomy was associated with higher all-cause mortality (HR=1.35; 95% CI, 1.32-1.39) than breast-conserving surgery plus radiation. Ten-year mortality rates also were higher among women who elected to undergo unilateral mastectomy than breast-conserving surgery plus radiation (20.1% vs. 16.8%).

Researchers observed no significant difference in all-cause mortality between women who underwent bilateral mastectomy and those who underwent breast-conserving surgery plus radiation (HR=1.02; 95% CI, 0.94-1.11). They also observed no significant difference in 10-year mortality between those groups (16.8% vs. 18.8%).

“Among all women diagnosed with early-stage breast cancer in California, the percentage undergoing bilateral mastectomy increased substantially between 1998 and 2011, despite a lack of evidence supporting this approach,” Kurian and colleagues wrote. “These results may inform decision-making about the surgical treatment of breast cancer … In a time of increasing concern about overtreatment, the risk–benefit ratio of bilateral mastectomy warrants careful consideration and raises the larger question of how physicians and society should respond to a patient’s preference for a morbid, costly intervention of dubious effectiveness.”

Disclosure: The researchers report receipt of grants from Genentech outside the submitted work.