Purpose: We investigated whether lower density of radiation treatment facilities was associated with lower by-county rates of radiation therapy (RT) after breast conserving surgery (BCS or lumpectomy) in the state of Maryland, and describe regional differences in RT uptake after BCS. Geographic and health system factors such as facility location, driving distance, and specialty shortages have been shown to influence RT use after BCS, a treatment regimen shown to be effective in preventing breast cancer recurrence. Differential uptake of RT after BCS may impact recurrence and survival, and contribute to racial and socioeconomic disparities in breast cancer mortality.

Methods: Secondary data analysis was conducted using Maryland Cancer Registry data, for the years 2000 to 2006, to examine the location of RT facilities and receipt of RT after BCS among African American (AA) and Caucasian (Cau) early stage breast cancer patients. Locations of RT facilities licensed by the Maryland Department of the Environment were geo-coded and mapped. Associations of by-county RT rates and density of radiation facilities (number of facilities per 100 square miles) were examined using linear regression models. Region-specific risk ratios of RT, adjusting for demographic, tumor, and health system variables, were estimated using generalized regression modeling.

Results: Initiation of RT was significantly associated with density of radiation facilities with an estimated 4.3% increase in RT for each additional facility per 100 square miles (p=0.03). In general, lower initiation of RT after BCS was observed in rural areas of Maryland where there were fewer RT facilities, and in Baltimore City, an urban area with a large number of RT facilities and a high concentration of AA and low income persons. In risk ratio modeling, lack of RT was associated with AA race (unadjusted RR 0.89; 95% CI 0.86-0.92), low income status (RR 0.91; 0.89-0.94), and lack of private insurance (RR 0.88; 0.86-0.90). In regional analysis with adjustment for diagnosis year, age group, race, low income status, insurance status, stage, grade, and tumor size, compared to patients residing in the National Metropolitan area, those residing in Southern Maryland, the Eastern Shore, the Baltimore Metropolitan area or in Baltimore City were less likely to initiate RT (Southern: RR 0.90; 95% CI 0.84-0.97; Eastern Shore: 0.89; 0.84-0.94; Baltimore Metro: 0.93; 0.91-0.96; Baltimore City: 0.87; 0.83-0.92).

Conclusions: Racial, socioeconomic, and geographic disparities in initiation of RT after BCS were documented in Maryland Cancer Registry data for 2000 through 2006. Intervention efforts to increase RT after BCS should target rural areas and socioeconomically disadvantaged urban populations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3721. doi:10.1158/1538-7445.AM2011-3721