Benefit of Adjuvant Radiotherapy After Breast-Conserving Therapy Among Elderly Women With T1-T2N0 Estrogen Receptor-Negative Breast Cancer

• Type of Material: Article
• Authors: Bree Eaton, Emory University; Renjian Jiang, Emory University; Mylin Torres, Emory University; Shannon Kahn, Emory University; Karen Godette, Emory University; Timothy Lash, Emory University; Kevin Ward, Emory University
• Language: English
• Date: 2016-09-20
• Publisher: Wiley
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016 American Cancer Society.
• Final Published Version (URL): http://dx.doi.org/10.1002/cncr.30142
• Title of Journal or Parent Work: Cancer
• ISSN: 0008-543X
• Volume: 122
• Issue: 19
• Start Page: 3059
• End Page: 3068
• Grant/Funding Information: Supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under award number UL1TR000454.
• Keywords: IRRADIATION; SURGERY; RADIATION; Oncology; estrogen receptor; RANDOMIZED-TRIAL; SUBTYPE; aged; mastectomy; OLDER; Life Sciences & Biomedicine; RECURRENCE; radiotherapy; Science & Technology; breast neoplasms
• Research Categories: Health Sciences, Oncology; Health Sciences, Public Health; Health Sciences, Epidemiology

Abstract

BACKGROUND: The purpose of the current study was to evaluate the impact of radiotherapy (RT) among women aged≥70 years with T1-2N0 estrogen receptor (ER)-negative breast cancer using Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked data. METHODS: The study included 3432 women, 2850 of whom received and 582 of whom did not receive RT after breast-conserving surgery. Outcomes were estimated by the cumulative incidence method and compared with the Gray test. The Fine and Gray subdistribution hazard regression models were used to assess the impact of RT and other variables. RESULTS: Women who received RT were more commonly aged < 75 years (42% vs 16%), had T1 tumors (78% vs 65%), ductal carcinoma histology (91% vs 88%), a Charlson-Deyo Comorbidity Index of 0 (41% vs 25%), and had received chemotherapy (29% vs 12%). The 5-year cumulative incidence of mastectomy and breast cancer-specific death for patients who received versus those did not receive adjuvant RT was 4.9% and 8.3% versus 10.8% and 24.1%, respectively (P < .001). On multivariable analysis, the omission of RT was found to be an independent predictor of an increased risk of mastectomy (hazard ratio, 2.33; 95% confidence interval, 1.56-3.49). Among women aged≥80 years or with T1N0 tumors, the mastectomy incidence with or without receipt of RT was 3.4% vs. 6.9%, and 5.3% vs 7.7%, respectively. CONCLUSIONS: The use of adjuvant RT after breast-conserving surgery in older women with T1-2N0 estrogen receptor-negative breast cancer is associated with a reduced incidence of future mastectomy and breast cancer death. The magnitude of benefit may be small for women aged ≥80 years or those with T1 tumors.