Abstract B122: Spatial analysis of ductal carcinoma in situ, locoregional, and distant metastatic breast cancer in North Carolina: Evidence for rural-urban disparities
Authors: Gearhart-Serna Larisa M , Hoffman Kate , Devi Gayathri R 
Published: September 2020

Introduction: A projected 8870 women will be diagnosed with breast cancer in North Carolina (NC) in 2019, with 1390 estimated deaths. However, breast cancer is a heterogenous disease, and investigating total incidence may hide differences in how sociodemographic factors impact the development of different subtypes of breast cancer, in particular early vs late stage aggressive phenotypes. The objective of this study was to investigate geographical variation of breast cancer in NC by stage, and to determine stage-specific associations with race and urbanicity. Methods: Breast cancer patient data were obtained from the NC Central Cancer Registry (NC CCR 2009-14) and stratified by stage and comprised of patients diagnosed with ductal carcinoma in situ (7975; DCIS), locoregional (38,200; combined localized, regional, and regional with direct extensions), or distant metastatic breast cancer (2073) based on derived summary staging defined by the Surveillance, Epidemiology, and End Results (SEER) program. Spatial distribution maps were generated in ArcMap 10.5.1 software for age-standardized incidence ratios (SIRs) by county using the NCCCR patient dataset described and age distributions from 2014 U.S. Census population estimates. Additionally, we stratified patients by rural-urban continuum code (RUCC), condensed for our purposes into three rural-urban categories: metropolitan urbanized, non-metro urbanized, and less populated. Results: DCIS, locoregional, and distant metastatic breast cancers all exhibited patterns of significantly different SIRs than expected based on state incidence rates in the northeastern region of NC, while DCIS and total breast cancer also had significantly different SIRs in the western region. Approximately 70% of patients inhabited metropolitan urbanized areas regardless of breast cancer stage, however, the highest incidence rates for all stages were consistently observed in less populated counties. Mean age at diagnosis for all stages was slightly higher in less populated areas, for example 61.4yrs DCIS and 62.8yrs distant metastatic breast cancer, than metropolitan areas, at 60.0yrs DCIS and 60.1yrs distant metastatic breast cancer. A higher percentage of distant metastatic breast cancer patients (29%) versus locoregional or DCIS patients (both 20%) in the dataset self-identified as Black, a pattern consistent across rural-urban categories. The percentage of current smokers was also higher for distant metastatic breast cancer cases (10%) than locoregional (6%) or DCIS cases (5%) across all rural-urban categories. Conclusions: Our results indicate that breast cancer incidence in NC varies geospatially by stage with incidence often higher in less populated areas. There were also age, race, and smoking status disparities across rural-urban stratifications and in patients with late stage breast cancer, which have the potential to contribute to poor survival outcomes in high risk patients.

Citation Format: Larisa M Gearhart-Serna, Kate Hoffman, Gayathri R Devi. Spatial analysis of ductal carcinoma in situ, locoregional, and distant metastatic breast cancer in North Carolina: Evidence for rural-urban disparities [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B122.