Effect of residence in nonmetropolitan counties on stage and tumor size at diagnosis in patients with breast cancer: A Surveillance, Epidemiology, and End Results analysis

Objective: The aim of this study was to assess the influence of residence in nonmetropolitan versus metropolitan counties on stage and tumor size at diagnosis in patients with breast cancer in the United States. Methods: Women with a primary diagnosis of breast cancer between 2010 and 2015 were selected from the Surveillance, Epidemiology, and End Results (SEER) database. Logistic regression was used to model the effect of residence in nonmetropolitan counties on cancer stage and tumor size, adjusted for age, marital status, and 2 county-level socioeconomic variables. Results: The final sample included 267,691 patients. More patients were diagnosed at advanced stages (III-IV vs I-II: 51.11% vs 50.21%) and with larger tumors (>2 cm vs < = 2 cm: 47.62% vs 46.77%) in nonmetropolitan counties. After adjustment, residence in nonmetro counties was not associated with advanced stage at diagnosis (OR = 0.987; 95% CI: 0.959-1.015) or tumor size >2 cm at diagnosis (OR = 0.997; 95% CI: 0.969-1.026). In stratified analysis by race/ethnicity, however, non-Hispanic White patients in nonmetropolitan counties were significantly more likely to have an advanced stage (OR = 1.035, 95% CI: 1.003-1.068) and tumor sizes >2 cm (OR = 1.051; 95% CI: 1.018-1.084) at diagnosis. Conclusions: Residence in nonmetropolitan counties in the United States was not associated with advanced stage or tumor size >2 cm at diagnosis in cases of breast cancer, compared to the residence in metropolitan counties. However, among non-Hispanic White females, residence in nonmetropolitan counties was associated with significantly higher odds of having an advanced stage and a tumor size >2 cm at diagnosis.