O. Kantor1, E. Leiderbach2, C. Wang3, D. J. Winchester2, C. E. Pesce2, K. Yao2 1University Of Chicago,Department Of Surgery,Chicago, IL, USA 2NorthShore University Health System,Department Of Surgery,Evanston, IL, USA 3Northshore University Health Systems,Center For Biomedical Research Informatics,Evanstol, IL, USA
Introduction:
Several randomized controlled trials in 2004 have examined the efficacy of radiation in elderly women with early stage breast cancer without demonstrating a survival benefit to radiation. Omission of radiation for this cohort has been incorporated into National Comprehensive Cancer Network guidelines for patients meeting criteria. We examined trends in radiation utilization for elderly patients since publication of these trials.
Methods:
Using the National Cancer Data Base (NCDB), radiation therapy utilization was determined for patients with early stage, estrogen receptor positive (ER+), clinically node negative invasive cancer treated with breast conserving surgery and hormone therapy from 2004 to 2011. Chi square tests and logistic regression models were used for analysis.
Results:
Adjuvant radiation therapy after breast conserving surgery decreased from 83.8% to 76.0% among those ≥70yo with ER+ tumors ≤2cm. For patients who did not receive hormonal therapy, radiation utilization significantly decreased from 60.7% to 52.4% over the study period. Among those patients who did not undergo radiation therapy, the rate of hormone therapy significantly increased from 36.9% to 52.7%. There is variation in the use of radiation according to patient and tumor factors; 95.3% of 60-69 year olds, 81.6% of 70-79 year olds, and only 59.1% of 80-90 year olds received radiation therapy in 2011. 83.2% of grade 3 tumors received radiation in 2011, compared to 73.3% of grade 1 tumors. Patients without lymph node staging were much less likely to receive radiation therapy compared to those that did (45.7% versus 77.8%).
The rate of external beam radiation has significantly decreased from 69.9% to 46.2%, while alternate forms of radiation have increased twofold from 14.2% to 29.8% (Figure 1). Brachytherapy has increased from 5% in 2004 to 11.7% in 2011. Independent predictors of receiving alternate forms of radiation include being treated at a community cancer center (OR 1.43, CI: 1.32-1.54), living >50 miles from the hospital (OR 1.50, CI:1.28-1.76), and living in the Mid-Atlantic (OR 2.42, CI: 2.16-2.71) or South Atlantic (OR 2.14, CI: 1.91-2.39) regions. Caucasian women, those with private insurance, grade 1 tumors, T1a tumors, and PR positive tumors were also more likely to receive alternate forms of radiation.
Conclusion:
Time trends in the NCDB reflect a gradual acceptance of evidence from randomized clinical trials supporting the omission of radiation therapy for women 70 and older with ER+ early stage breast cancer. However, the majority still receive radiation, influenced by tumor size and grade, and many are receiving alternate forms of radiation, particularly brachytherapy.
