EFFECT OF RURALITY ON STAGE AT DIAGNOSIS, TUMOR SIZE AT DIAGNOSIS, AND RECEIPT OF CANCER-DIRECTED SURGERY IN PATIENTS WITH BREAST CANCER: A SURVEILLANCE, EPIDEMIOLOGY, AND END RESULTS (SEER) ANALYSIS
Open Access
- Author:
- Benavides Vasquez, Jorge
- Graduate Program:
- Clinical Research
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 19, 2021
- Committee Members:
- Li Wang, Thesis Advisor/Co-Advisor
Alicia Mcdonald, Committee Member
Chan Shen, Committee Member
Li Wang, Program Head/Chair - Keywords:
- rural
urban
rurality
urbanicity
breast cancer
stage
tumor size
surgery
SEER
female
race
ethnicity - Abstract:
- Background Few studies have analyzed the influence of rural/urban disparities on the risks of advanced stage and large tumor size of breast cancer at diagnosis in the United States using a large population sample from national cancer registry data. The aim of the present study was to assess the influence of rural/urban residence as a risk factor for advanced-stage at diagnosis, tumor size larger than 2 cm at diagnosis, and receipt of cancer-directed surgery in females with primary breast cancer in the United States. Methods A selected sample of female patients with a primary diagnosis of breast cancer between 2010-2015 was obtained from the National Cancer Institute (NCI)’s Surveillance, Epidemiology, and End Results (SEER) database. Outcome variables were: Probability of advanced stage (AJCC stages II-IV) at diagnosis, probability of tumor size >2 cm at diagnosis, and receipt of cancer-directed surgery (surgery aimed at treating the main tumor). The primary independent variable was county-level rural/urban residence. Logistic regression was used to measure the association between the main independent and the main outcome variables, adjusted for age, grade, immunohistochemical subtype, marital status, county percentage of families below poverty level, and county percentage of individuals with at least bachelor’s degree. Statistical analysis was stratified by race/ethnicity. Results The final sample included 272,448 female breast cancer cases, of which 42.53% were older than 75 years, 68.26% were non-Hispanic Whites, and 90.36% lived in metropolitan counties. Cases in non-metropolitan counties were diagnosed at more advanced stages (III and IV), had more tumors larger than 2 cm at diagnosis, and had more aggressive immunohistochemical breast cancer subtypes (HR-/HER2+, TNBC) at diagnosis. A lower percentage of women living in metropolitan counties (95.9%) received cancer-directed surgery than those living in rural/adjacent counties (97.32%). Adjusted multivariate logistic regression analysis showed that non-Hispanic White patients living in urban/not adjacent counties were significantly more likely to be diagnosed with advanced breast cancer than those in metro counties (OR=1.055; 95%CI, 1.005-1.107), and those living in urban/not adjacent (OR=1.065; 95%CI, 1.014-1.117) or urban/adjacent counties (OR=1.172; 95%CI, 1.045-1.314) were more likely to have a breast tumor larger than 2 cm at diagnosis than those living in metro counties. These differences were not significant for other urban/rural residence and race/ethnicity categories. Conclusion Urban/rural residence was found to be significantly associated with advanced stage and a tumor larger than 2 cm at diagnosis in non-Hispanic White female breast cancer cases in the United States. However, statistically significant associations were not observed among non-Hispanic Black, non-Hispanic Asian/Pacific Islander, and Hispanic patients. Future research efforts will need to further investigate the complex association between rurality and cancer outcomes across different race/ethnicity categories.