Rurality and Income on Breast Cancer Outcomes: An Analysis of the SEER Database.

[INTRODUCTION] Disparate breast cancer outcomes have been reported in rural settings and for lower-income patients. There are limited data on the interaction between rurality and income in breast cancer outcomes, particularly at the national level.

[PATIENTS AND METHODS] The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program's 17 Registry was queried for new breast cancer diagnoses (2004-2020). Location was defined as rural or urban on the basis of SEER's Rural-Urban Continuum Codes. Annual income was defined as lower (≤ $55,000) or higher (> $55,000). Data were stratified by rurality and income level. Oncologic factors and outcomes were compared.

[RESULTS] Of 815,220 breast cancer cases identified, 57,063 were rural lower-income (RLI), 55,667 were urban lower-income (ULI), 29,762 were rural higher-income (RHI), and 672,728 were urban higher-income (UHI). RLI patients were more likely to be diagnosed with localized (breast only) disease (66.06% versus 65.34%, P = 0.01) and over age 75 (31.52% versus 28.58%, P < 0.001) compared with ULI patients. ULI patients had higher rates of estrogen receptor-negative (20.26% versus 18.97%, P < 0.001) and HER2-positive (10.74% versus 9.27%, P < 0.001) disease compared with RLI patients. ULI patients had higher lumpectomy rates compared with RLI patients (53.01% versus 51.26%, P < 0.001) and were more likely to undergo chemotherapy (43.69% versus 41.08%, P < 0.001) or radiation (52.65% versus 47.67%, P < 0.001).

[CONCLUSIONS] For patients with breast cancer, both income level and residential setting are associated with disparate clinical presentations and treatment patterns. This complex interaction between rurality and income merits additional study to understand the geospatial distribution of disparities and investigate potential interventions.