Use of surgery for de novo metastatic breast cancer (mBC).
Authors: Dickerson James , Tang Hao , Thompson Candice , Gomez Scarlett L. , Satoyoshi Mina , Kurian Allison W. , Caswell-Jin Jennifer Lee 
Published: May 2024

1590 Background: In the U.S., locoregional surgery for de novo mBC was common in the 1990s and 2000s, but subsequent prospective data did not show a survival advantage. Current guidelines recommend surgery only for symptom control. We investigated trends in the use of surgery (lumpectomy or mastectomy) for mBC from 2010 to 2019 using SEER and institutional data, aiming to identify factors that correlate with variability in surgery use. Methods: We included all de novo mBC diagnoses from SEER-17 from 2010-2019. The primary outcome was receipt of surgery, and we included year of diagnosis, demographic (race/ethnicity, age, marital status, median household income in the patient’s county, and urban/rural residence), and disease factors (estrogen receptor (ER) and HER2 status, tumor size, and presence of visceral metastases) in the multivariable logistic regression. We similarly identified all de novo mBC diagnoses from Oncoshare, which merges EMR and California Cancer Registry (CCR) data for patients treated in the Stanford Health Care Alliance. For Oncoshare inclusion a patient must have an encounter with Stanford and be in CCR; however, a patient does not have to receive all cancer care at Stanford. In this analysis, we included distance to the cancer center and insurance status. Results are presented as unadjusted percentages or odds ratios with 95% confidence intervals. Results: In SEER (n = 24,146), the use of surgery for mBC declined from 41% in 2010 to 22% in 2019, a trend also observed in the institutional data (n = 785). Surgery rates were highest in younger patients and declined with each decade of life (44% for those in their 30s vs 19% for those > 80). Surgery was more common in tumors > 2 cm, ER-negative disease, and in patients without visceral metastases. In SEER, patients from counties with median incomes < $50,000 were more likely to have surgery than those from counties with incomes > $75,000 (36% vs 27%; OR: 1.3 [1.2-1.5]). Rural patients were more likely to have surgery than urban patients (34% vs 30%; OR: 1.1 [1.0-1.3]). Unmarried persons had lower odds of surgery than married persons (OR: 0.8 [0.7-0.9]). The institutional data reproduced the findings of the SEER analysis, except that a relationship between surgery and marital status and income was not observed. In the institutional data, patients living farther from the Stanford Cancer Center ( > 100 km) were more likely to have surgery (40% vs 32%; OR 2.1 [1.2-3.8]). Conclusions: The use of surgery for de novomBC decreased dramatically in the 2010s from 41% to 22%. All demographics saw a reduction; however, younger, and married patients underwent surgery at higher rates. Patients from lower-income and rural counties—areas typically with less access to care—were also more likely to have surgery. The institutional analysis showed that a greater distance from an urban hospital network correlated with increased odds of surgery. These patterns suggest differential care provision in rural areas for patients with mBC.