Utilization of accelerated partial-breast irradiation (APBI) and guideline concordance: Analysis of the National Cancer Database.

Abstract

54 Background: ASTRO published a consensus statement on patient suitability for APBI treatment to guide physician practice. The purpose of this study was to examine utilization trends of APBI in the American College of Surgeons’ National Cancer Database and to assess changes in APBI use following publication of the ASTRO guidelines in 2009. Methods: A total of 337,910 women were identified who were diagnosed from 2004 to 2010 with non-metastatic invasive breast cancer or ductal carcinoma in situ who were treated with breast conserving surgery and radiation therapy (RT) to the breast. Patients were divided by the type of treatment received (whole breast irradiation (WBI) or APBI) and by suitability to receive APBI as defined by the ASTRO Consensus Statement. Logistic regression was applied to study APBI use overall and within consensus statement categorization. All p-values are two-sided. Results: For all patients, APBI usage increased as an alternative to WBI over time, from 3.8% in 2004 to 10.8% in 2008, with a subsequent decline to 9.9% in 2010, due to a decline in APBI use for “cautionary”/“unsuitable” patients (p<0.0001). Overall rates of APBI utilization were higher among “suitable” than “cautionary”/“unsuitable” patients (range 6.9% to 16.9% vs. 3.1% to 7.8%, p<0.0001). Among all patients, the most common modality of delivering APBI was brachytherapy (82%), followed by external beam RT (17%) and intraoperative RT (1.0%). For both “suitable” and “cautionary”/“unsuitable” patients, factors associated with treatment with APBI included treatment after 2004 (p<0.0001), well differentiated histology (p<.0001), and smaller tumor size (p<0.0001). For “cautionary”/“unsuitable” patients, those with grossly negative tumor margins were more likely to receive APBI, as were “suitable” patients treated at an academic or comprehensive community cancer program compared to a community cancer program (both p<0.0001). Conclusions: The highest absolute rate of use of APBI was seen in the group considered “suitable” by ASTRO guidelines. Although significant increases have also been seen among less suitable cohorts, these rates have declined since the publication of the ASTRO guidelines in 2009.