Study Finds Significant Increase in Bilateral Mastectomies Despite Lack of Survival Benefit
Results from a large population-based study of 189,734 women diagnosed with early-stage breast cancer in California show the percentage opting for a bilateral mastectomy has increased substantially over the past decade even though the procedure was not associated with a lower risk of death than breast-conserving surgery plus radiation.
Women who underwent bilateral mastectomy were more likely to be non-Hispanic white, privately insured, living in high-socioeconomic-status neighborhoods, treated in National Cancer Institute (NCI)-designated cancer centers, and younger than age 40. In contrast, women who underwent unilateral mastectomy were more likely to be Asian, Hispanic, or non-Hispanic American Indian; have public or Medicaid insurance; and less likely to live in high-socioeconomic-status neighborhoods or be treated in NCI-designated cancer centers. The study also found that compared with bilateral mastectomy and breast-conserving surgery, unilateral surgery was associated with a higher risk of death. The study by Kurian et al is published in JAMA.
Study Methodology
The researchers analyzed data of the use and outcomes of bilateral mastectomy compared with other surgical treatments from the California Cancer Registry (CCR), which is part of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program, and comprises about 99% of all breast cancer cases statewide. The women were diagnosed with stage 0 to III unilateral breast cancer in California from 1998 to 2011, with a median follow-up of 89.1 months.
Study Findings
The researchers found that the rate of bilateral mastectomy increased from 2.0% (95% confidence interval [CI] = 1.7%–2.2%) in 1998 to 12.3% (95% CI = 11.8%–12.9%) in 2011, an annual increase of 14.3% (95% CI = 13.1%–15.5%). Among women younger than 40, the rate increased from 3.6% (95% CI = 2.3%–5.0%) in 1998 to 33% (95% CI = 29.8%–36.5%) in 2011.
Compared with breast-conserving surgery with radiation (10-year mortality = 16.8%, 95% CI = 16.6%–17.1%), unilateral mastectomy was associated with higher all-cause mortality (hazard ratio [HR] = 1.35, 95% CI = 1.32–1.39, 10-year mortality = 20.1%, 95% CI = 19.9%–20.4%). There was no significant mortality difference compared with bilateral mastectomy (HR = 1.02, 95% CI = 0.94–1.11; 10-year mortality = 18.8%, 95% CI = 18.6%–19.0%). Propensity analysis showed similar results.
“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,” wrote the study authors. “These results may inform decision-making about the surgical treatment of breast cancer.”
Scarlett L. Gomez, PhD, of the Cancer Prevention Institute of California, is the corresponding author for the JAMA article.
The study was funded by Jan Weimer Junior Faculty Chair in Breast Oncology, the Suzanne Pride Bryan Fund for Breast Cancer Research at Stanford Cancer Institute, and the NCI SEER program grant awarded to the Cancer Prevention Institute of California.
Dr. Gomez and Christina A. Clarke, PhD, reported receiving grants from Genetech. The other study authors reported no conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
