Association between access to accelerated partial breast irradiation and use of adjuvant radiotherapy

BACKGROUNDThe current study was performed to determine whether access to facilities performing accelerated partial breast irradiation (APBI) is associated with differences in the use of adjuvant radiotherapy (RT). METHODSUsing the National Cancer Data Base, the authors performed a retrospective study of women aged 50 years who were diagnosed with early-stage breast cancer between 2004 and 2013 and treated with breast-conserving surgery (BCS). Facilities performing APBI in 10% of their eligible patients within a given year were defined as APBI facilities whereas those not performing APBI were defined as non-APBI facilities. All other facilities were excluded. The authors identified independent factors associated with RT use using multivariable logistic regression with clustering in the overall sample as well as in subsets of patients with standard-risk invasive cancer, low-risk invasive cancer, and ductal carcinoma in situ. RESULTSAmong 222,544 patients, 76.6% underwent BCS plus RT and 23.4% underwent BCS alone. The likelihood of RT receipt in the overall sample did not appear to differ significantly between APBI and non-APBI facilities (adjusted odds ratio [AOR], 1.02; P=.61). Subgroup multivariable analysis demonstrated that among patients with standard-risk invasive cancer, there was no association between evaluation at an APBI facility and receipt of RT (AOR, 0.98; P=.69). However, patients with low-risk invasive cancer were found to be significantly more likely to receive RT (54.4% vs 59.5%; AOR, 1.22 [P<.001]), whereas patients with ductal carcinoma in situ were less likely to receive RT (56.9% vs 55.3%; AOR, 0.89 [P=.04]) at APBI facilities. CONCLUSIONSPatients who were eligible for observation were more likely to receive RT in APBI facilities but no difference was observed among patients with standard-risk invasive cancer who would most benefit from RT. Cancer 2017;123:502-511. (c) 2016 American Cancer Society. Facilities that offer partial breast irradiation are more likely to administer radiotherapy to women eligible for its omission. The availability of partial breast irradiation does not appear to improve compliance with radiation after lumpectomy.