Limitations of the American Society of Therapeutic Radiology and Oncology (ASTRO) Consensus Panel Guidelines on the Use of Accelerated Partial Breast Irradiation

Abstract

We applied the American Society of Therapeutic Radiology and Oncology (ASTRO) Consensus Panel (CP) guidelines for the use of accelerated partial breast irradiation (APBI) to patients treated with this technique to determine their ability to differentiate patients with significantly different clinical outcomes. One hundred ninety-nine patients treated with APBI and 199 with whole breast irradiation (WBI) (matched for tumor size, nodal status, age, margins, receptor status, and tamoxifen use) were stratified into the three ASTRO CP levels of suitability (suitable [S], cautionary [C], and unsuitable [U]) to assess rates of ipsilateral breast tumor recurrence (IBTR), regional nodal failure (RNF), distant metastases (DM), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS) based upon CP category. Median follow-up was 11.1 years. Analysis of the APBI and WBI patient groups, either separate or together (n = 398), did not demonstrate statistically significant differences in 10-year actuarial rates of IBTR when stratified by the three ASTRO groups. Regional nodal failure and DM were generally progressively worse when comparing the S to C to U CP groups. However, when analyzing multiple clinical, pathologic or treatment related variables, only patient age was associated with IBTR using WBI (p = 0.002). The ASTRO CP suitable group predicted for a low risk of IBTR; however, the C and U groups had an equally low risk of IBTR supporting the need for continued refinement of patient selection criteria as additional outcome data become available and for the continued accrual of patients to phase III trials.