Background: Accelerated partial breast irradiation using brachytherapy (APBIb) is an alternative to whole-breast irradiation (WBI) after breast-conserving surgery. We evaluated patterns of APBIb use with respect to 2009 American Society for Radiation Oncology consensus guidelines (ASTRO-G) in a population-based cohort.
Methods: From Surveillance, Epidemiology, and End Results data, we identified 138 815 American women with breast cancer diagnosed between January 1, 2000, and December 31, 2007, who underwent WBI or APBIb after breast-conserving surgery and classified them as suitable, cautionary, or unsuitable for APBIb according to ASTRO-G criteria. Logistic regression was applied to study APBIb use overall and within each guideline category. All P values are from two-sided tests.
Results: Overall, 2.6% of patients received APBIb, and 65.8% of them were classified as cautionary or unsuitable. APBIb was used by 5% of suitable, 3.4% of cautionary, and 1.6% of unsuitable patients by ASTRO-G criteria (P < .001). APBIb use increased from 0.4% in 2000 to 6.6% in 2007 and varied widely (0%-7%) between localities. Variables associated with APBIb use among suitable patients included other vs white race (odds ratio [OR] = 0.51, P < .001), region (OR = 2.60-8.62, P < .001), and more recent year (OR = 20.3, P < .001). Among cautionary patients, variables associated with APBIb use included black vs white race (OR = 0.76, P = .027), other vs white race (OR = 0.57, P < .001), Hispanic ethnicity (OR = 0.75, P = .036), region (OR = 3.10-10.2, P < .001), nonmetropolitan or rural location (OR = 0.53, P = .012), and more recent year (OR = 17.6, P < .001). Among unsuitable patients, black vs white race (OR = 0.77, P = .008), other vs white race (OR = 0.46, P < .001), region (OR = 3.33-21.6, P < .001), and more recent year (OR = 12.7, P < .001) were associated with APBIb use.
Conclusions: APBIb after breast-conserving surgery has been rapidly adopted in the United States. Use varied by race, ethnicity, and widely by region, especially among patients who may not be suitable for this radiation technique.