Selection criteria for accelerated partial-breast irradiation: impact on applicability

This study examines the potential applicability of accelerated partial-breast irradiation (APBI) based on clinical and pathologic selection criteria in patients with stage I/II breast cancer. The records of 535 patients treated with breast-conserving surgery and radiation were reviewed. The patient database was analyzed for the following factors: age, extensive intraductal carcinoma (EIC), lymphovascular invasion (LVI), margin status, histologic type, pathologic nodal status, and pathologic tumor size. Two hundred seventeen records were located. The minimal selection criteria for APBI were assumed to include patient age of >/= 45 years, nonlobular histology, negative margins (> 2 mm), absence of EIC, and node-negative status. The potential variations in selection criteria for age, tumor size, and LVI were investigated with regard to the proportion of patients who would be eligible for APBI. In addition, predictors for true versus diffuse recurrence were examined among 40 patients who had a local recurrence. Using variable patient age cutoffs and T2 tumors as well as LVI, 9%-47% of patients could have been considered for APBI in this study. Using an age cutoff of >/= 65 years, 9%-15% of patients could have been eligible for APBI. However, using an age cutoff of >/=45 years, 28%-47% might be eligible, with the consideration of LVI becoming important. Among 40 local recurrences, 12 occurred at the primary site; 15 occurred elsewhere, diffusely, or with dermal involvement; and the locations of 13 could not be determined. Extensive intraductal carcinoma was the only significant predictor for recurrence at the primary site (P = 0.01). The potential impact of APBI on breast radiation therapy practice needs to be further delineated, and appropriate selection criteria should be refined.