P1-11-05: Investigation of Epidemiological Factors as Barriers to Indicated Radiation Therapy in Post-Mastectomy Breast Cancer Patients in South Carolina.
Authors: Rhome RM , Wahlquist A , Garrett-Mayer E , Harper J 
Published: June 2012

Abstract
Purpose: Post-mastectomy radiation therapy (PMRT) has been shown to provide improved locoregional control and overall survival in intermediate and high-risk breast cancer patients1,2. To investigate the frequency of utilization and potential barriers to receipt of adjuvant PMRT in South Carolina, an analysis of the S.C. Cancer Registry (SCCR) database was undertaken.
Methods: Epidemiological factors such as age, race, and geographic distance from a radiation therapy facility were analyzed as potential predictors of whether patients received the indicated radiotherapy. Post-mastectomy breast cancer patients (n=1080) recorded in the SCCR from 2006–2008 were stratified as low (Tis/T1, N0) (43%), intermediate (T1/T2, N1) (27%), or high (T3/T4, N2/N3) (30%) risk. Logistic regression models were used to predict receipt of adjuvant radiotherapy based on factors such as race, age, and geographical distance from radiation treatment facility.
Results: Adjuvant PMRT was received in 4% (19/469) of low risk patients, 23% (67/288) of intermediate risk patients, and 44% (141/323) of high risk patients. In both intermediate and high risk groups, older patients were less likely to receive PMRT. The odds of receiving PMRT decreased by 3% (OR= 1.03; 95% CI: 1.01−1.05; p=0.01) and 2% (OR=1.02; 95% CI: 1.002−1.035; p=0.03) per year in the intermediate and high risk groups, respectively. Race and distance from treatment facility were not predictive of receipt of PMRT in high risk patients.
Conclusion: Utilization of adjuvant PMRT in intermediate and high risk breast cancer patients in South Carolina is low, despite the evidence that it confers a survival benefit in both premenopausal and postmenopausal women. Of the patient-related factors analyzed, only age predicted lower odds of receiving radiotherapy in both the intermediate and high risk group. In high risk patients of advanced age (&gt;70), breast cancer continues to be a major cause of mortality which can be improved by radiotherapy3. Future educational efforts should focus on addressing patient and physician bias against radiotherapy based on patient age. Further study is needed to identify socio-economic-, physician- and health system- related factors that maybe impacting the underutilization of PMRT in South Carolina.
References:
1. Overgaard, M, PS Hansen, et al. 1997. Postoperative radiotherapy in high-risk premenopausal women with breast cancer who receive adjuvant chemotherapy. NEJM, 337:14, pg 949–955.
2. Overgaard M, Jensen M-J, Overgaard J, et al. 1999. Postoperative radiotherapy in high-risk postmenopausal breast-cancer patients given adjuvant tamoxifen: Danish Breast Cancer Cooperative Group DBCG 82c randomised trial. Lancet. 353: 1641–1648.
3. Smith, BD, BG Haffty, A Hurria, DH Galusha, and CP Gross. 2006. Postmastectomy radiation and survival in older women with breast cancer. JCO, 24:30, pg 4901–4907.
Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-11-05.