In an observational cohort study reported in JAMA, Allison W. Kurian, MD, MSc, Assistant Professor of Medicine and of Health Research and Policy at Stanford University School of Medicine, and colleagues assessed use of and mortality after bilateral mastectomy, breast-conserving surgery plus radiation, and unilateral mastectomy between 1998 and 2011 in California women with unilateral stage 0 to III breast cancer.¹

Use of bilateral mastectomy has increased markedly, particularly among younger women. All-cause and breast cancer–specific mortality were similar with bilateral mastectomy and breast-conserving surgery plus radiation and lower with these two treatments vs unilateral mastectomy.

The study involved data from 189,734 patients in the population-based California Cancer Registry. Median follow-up was 89.1 months.

Use of Bilateral Mastectomy

Use of bilateral mastectomy increased from 2.0% in 1998 to 12.3% in 2011, an annual increase of 14.3%. Among women aged < 40 years, use increased from 3.6% to 33%.

Use of breast-conserving surgery plus radiation remained fairly stable, increasing from 51.7% in 1998 to 54.2% in 2011. Use of unilateral mastectomy decreased from 46.3% in 1998 to 33.4% in 2011.

Compared with breast-conserving surgery plus radiation, bilateral mastectomy was more often used by non-Hispanic white women (eg, multiple regression odds ratios [ORs] = 0.41 for Chinese, 0.61 for Filipina, 0.63 for Hispanic, and 0.53 for black women), those with private insurance (eg, OR = 0.66 for public insurance or Medicaid), and those who received care at a National Cancer Institute (NCI)-designated cancer center (OR = 1.13).

Other characteristics significantly associated with increased use of bilateral mastectomy were younger age (eg, ORs = 2.00 for 40–49 years and 3.81 for < 40 years vs 50–64 years), larger tumors (OR = 1.36 per cm), involved lymph nodes (OR = 1.66), lobular vs ductal histology (OR = 2.19), higher tumor grade (ORs = 1.17 for II vs I and 1.30 for III vs I), hormone receptor–negative status (OR = 1.12 vs positive), no receipt of adjuvant therapy (OR = 0.91 for receipt), higher neighborhood socioeconomic quintile (eg, ORs = 1.41 for quintile 5 and 1.22 for 4 vs 1), unmarried status (OR = 0.95 for married), treatment at a hospital with > 50% of patients in lower socioeconomic status quintiles (eg, OR = 1.12 for 1 and 2 vs 4 and 5), and diagnosis in 2005 to 2011 vs 1998 to 2004 (OR = 2.73).

Use of Unilateral Mastectomy

Compared with breast-conserving surgery plus radiation, unilateral mastectomy was more often used by racial/ethnic minorities (eg, ORs = 2.00 for Filipina and 1.16 for Hispanic vs non-Hispanic white women) and patients with public/Medicaid insurance (eg, OR = 1.08 vs private insurance).

Other factors significantly associated with increased use of unilateral mastectomy were age (ORs = 1.15 for 40–49 years, 1.31 for < 40 years, and 1.34 for ≥ 65 years vs 50–64 years), larger tumor size (OR = 1.61 per cm), lymph node involvement (OR = 2.16), lobular vs ductal histology (OR = 1.36), higher tumor grade (ORs = 1.18 for II vs I and 1.24 for III vs I), hormone receptor–negative status (OR = 1.17 vs positive), lower neighborhood socioeconomic quintile (eg, ORs = 0.91 for 2, 0.85 for 3, and 0.73 for 5 vs 1), married status (OR = 1.07), treatment at a hospital with >50% of patients in lower socioeconomic status quintiles (eg, OR = 1.49 for 1 and 2 vs 4 and 5), receipt of care at a non–NCI-designated cancer center (OR = 0.81 for care at NCI-designated center), and diagnosis in 1998 to 2004 vs 2005 to 2011 (OR = 0.84 for 2005–2011).

Overall and Breast Cancer–Specific Mortality

On multiple regression analysis, unilateral mastectomy was associated with significantly greater risk of 10-year all-cause mortality (20.1% vs 16.8%, hazard ratio [HR] = 1.35, 95% confidence interval [CI] = 1.32–1.38) and breast cancer–specific mortality (HR = 1.29, 95% CI = 1.23–1.35) vs breast-conserving surgery plus radiation.

There was no significant difference between bilateral mastectomy (18.8%) and breast-conserving surgery in 10-year overall mortality (HR = 1.02, 95% CI = 0.94–1.11) or cancer-specific mortality (HR = 1.09, 95% CI = 0.98–1.21). Compared with unilateral mastectomy, bilateral mastectomy was associated with significantly lower risk of 10-year overall mortality (HR = 0.75, 95% CI = 0.70–0.82) and breast cancer–specific mortality (HR = 0.85, 95% CI = 0.76–0.94).

Other factors associated with increased risk of overall mortality on multiple regression analysis included non-Hispanic white race vs all other race/ethnicity groups except black race, age < 40 or ≥ 65 at diagnosis, increased tumor size, lymph node involvement, ductal histology, higher tumor grade, hormone receptor–negative status, no receipt of adjuvant therapy, residence in lower socioeconomic status quintiles, and unmarried status.

The investigators concluded:

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. Bilateral mastectomy was not associated with lower mortality than breast-conserving surgery plus radiation, but unilateral mastectomy was associated with higher mortality than the other options. These results may inform decision-making about the surgical treatment of breast cancer.

Scarlett L. Gomez, PhD, of Stanford University School of Medicine, is the corresponding author for the JAMA article. ■

Disclosure: The study was supported by the JanWeimer Junior Faculty Chair in Breast Oncology, Suzanne Pride Bryan Fund for Breast Cancer Research at Stanford Cancer Institute, and the NCI. For full disclosures of the study authors, visit jama.jamanetwork.com.

Reference

1. Kurian AW, Lichtensztajn DY, Keegan THM, et al: Use of and mortality after bilateral mastectomy compared with other surgical treatments for breast cancer in California, 1998-2011. JAMA 312:902-914, 2014.