title: Seven-Year Outcomes Following Accelerated Partial Breast Irradiation Stratified by ASTRO Consensus Groupings.
abstract: OBJECTIVE
  Limited long-term data exist regarding outcomes for patients treated with accelerated partial breast irradiation (APBI), particularly, when stratified by American Society for Radiation Oncology (ASTRO) Consensus Statement (CS) risk groups. The purpose of this analysis is to present 5- and 7-year outcomes following APBI based on CS groupings.
  
  
  METHODS
  A total of 690 patients with early-stage breast cancer underwent APBI from 1993 to 2012, receiving interstitial brachytherapy (n=195), balloon-based brachytherapy (n=290), or 3-dimensional conformal radiotherapy (n=205) at a single institution. Patients were stratified into suitable, cautionary, and unsuitable groups with 5-year outcomes analyzed. Seven-year outcomes were analyzed for a subset with follow-up of ≥2 years (n=625).
  
  
  RESULTS
  Median follow-up was 6.7 years (range, 0.1 to 20.1 y). Patients assigned to cautionary and unsuitable categories were more likely to have high-grade tumors (21% to 25% vs. 9%, P=0.001), receive chemotherapy (15% to 38% vs. 6%, P<0.001), and have close/positive margins (9% to 11% vs. 0%, P<0.001). There was no difference in ipsilateral breast tumor recurrence at 5 or 7 years: 2.2%, 1.2%, 2.8% at 5 years (P=0.57), and 2.2%, 1.9%, 4.6% at 7 years (P=0.58) in the suitable, cautionary, and unsuitable groups, respectively. As compared with the suitable group, increased rates of distant metastases were noted for the unsuitable and cautionary groups at 5 years (P=0.04).
  
  
  CONCLUSIONS
  No differences in rates of ipsilateral breast tumor recurrence were seen at 5 or 7 years when stratified by ASTRO CS groupings. Modest increases in distant recurrence were noted in the cautionary and unsuitable groups. These findings suggest that the ASTRO CS groupings stratify more for systemic recurrence and may not appropriately select patients for whole versus partial breast irradiation.
authors.affiliation: *Department of Radiation Oncology, Oakland University William Beaumont School of Medicine, Royal Oak, MI †Department of Radiation Oncology, Summa Cancer Institute, Summa Health System, Akron, OH ‡Department of Radiation Oncology, Willis-Knighton Health System/LSU Health Science Center, Shreveport, LA.
authors.forename: Maha S
authors.initials: MS
authors.lastname: Jawad
authors.forename: Chirag
authors.initials: C
authors.lastname: Shah
authors.forename: J Ben
authors.initials: JB
authors.lastname: Wilkinson
authors.forename: Michelle
authors.initials: M
authors.lastname: Wallace
authors.forename: Christina K
authors.initials: CK
authors.lastname: Mitchell
authors.forename: Jessica
authors.initials: J
authors.lastname: Wobb
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Gustafson
authors.forename: Donald S
authors.initials: DS
authors.lastname: Brabbins
authors.forename: Inga S
authors.initials: IS
authors.lastname: Grills
authors.forename: Peter Y
authors.initials: PY
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D001943:Breast Neoplasms / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy*; D032921:Consensus; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D020266:Radiotherapy, Conformal / Q000379:methods*; D016019:Survival Analysis; D016896:Treatment Outcome