Radiation Therapy for Positive Surgical Margins in Women ≥70 Years with Stage I, Estrogen Receptor-positive Breast Cancer

Background/Aim: A re-excision for positive margin(s) following a lumpectomy for invasive breast cancer is a standard recommendation. However, for elderly women with stage I estrogen receptor-positive (ER+) tumors, who may be at higher surgical risk, whether radiation therapy without re-excision will be adequate is not known. Patients and Methods: We evaluated a cohort of 53,950 women aged >= 70 years with Stage I, ER+ breast cancer who had lumpectomy and anti-hormone therapy diagnosed between 2004 and 2011 in the National Cancer Data Base. Patients were divided into four groups: 1) negative margins without radiation (XRT), 2) negative margins with XRT, 3) positive margins without XRT, and 4) positive margins with XRT. Clinicopathological and sociodemo graphic variables were compared among these groups. Univariable and multivariable analysis were employed. Results: The 5-year overall survival (OS) rates for the groups were as follows: 1) negative margins without radiation (XRT); 77.1%, 2) negative margins with XRT; 90.0%, 3) positive margins without XRT; 62.9%, and 4) positive margins with XRT; 86.8% (p<0.0001). Significant predictors (p<0.01) of OS include treatment groups, age, income status, facility type, facility location, tumor size, tumor grade, and comorbidities. Conclusion: Radiation therapy for positive surgical margins without re-excision may be a viable option for elderly women with stage I, ER+ tumor treated with lumpectomy and hormonal therapy.