title: The association between biological subtype and isolated regional nodal failure after breast-conserving therapy.
abstract: OBJECTIVE
  To evaluate the risk of isolated regional nodal failure (RNF) among women with invasive breast cancer treated with breast-conserving surgery (BCS) and radiation therapy (RT) and to determine factors, including biological subtype, associated with RNF.
  
  
  METHODS
  We retrospectively studied 1,000 consecutive women with invasive breast cancer who received breast-conserving surgery and RT from 1997 through 2002. Ninety percent of patients received adjuvant systemic therapy; none received trastuzumab. Sentinel lymph node biopsy was done in 617 patients (62%). Of patients with one to three positive nodes, 34% received regional nodal irradiation (RNI). Biological subtype classification into luminal A, luminal B, HER-2, and basal subtypes was based on estrogen receptor status-, progesterone receptor status-, and HER-2-status of the primary tumor.
  
  
  RESULTS
  Median follow-up was 77 months. Isolated RNF occurred in 6 patients (0.6%). On univariate analysis, biological subtype (p = 0.0002), lymph node involvement (p = 0.008), lymphovascular invasion (p = 0.02), and Grade 3 histology (p = 0.01) were associated with significantly higher RNF rates. Compared with luminal A, the HER-2 (p = 0.01) and basal (p = 0.08) subtypes were associated with higher RNF rates. The 5-year RNF rate among patients with one to three positive nodes treated with tangents alone was 2.4%; we could not identify a subset of these patients with a substantial risk of RNF.
  
  
  CONCLUSIONS
  Isolated RNF is a rare occurrence after breast-conserving therapy. Patients with the HER-2 (not treated with trastuzumab) and basal subtypes appear to be at higher risk of developing RNF although this risk is not high enough to justify the addition of RNI. Low rates of RNF in patients with one to three positive nodes suggest that tangential RT without RNI is reasonable in most patients.
authors.affiliation: Harvard Radiation Oncology Program, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Jennifer Y
authors.initials: JY
authors.lastname: Wo
authors.forename: Alphonse G
authors.initials: AG
authors.lastname: Taghian
authors.forename: Paul L
authors.initials: PL
authors.lastname: Nguyen
authors.forename: Rita Abi
authors.initials: RA
authors.lastname: Raad
authors.forename: Meera
authors.initials: M
authors.lastname: Sreedhara
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Bellon
authors.forename: Julia S
authors.initials: JS
authors.lastname: Wong
authors.forename: Michele A
authors.initials: MA
authors.lastname: Gadd
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Smith
authors.forename: Jay R
authors.initials: JR
authors.lastname: Harris
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000737:chemistry / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D017024:Chemotherapy, Adjuvant; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology; D015182:Lymphatic Irradiation; D008207:Lymphatic Metastasis / Q000473:pathology* / Q000532:radiotherapy; D015412:Mastectomy, Segmental; D009361:Neoplasm Invasiveness; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012189:Retrospective Studies; D012306:Risk; D021701:Sentinel Lymph Node Biopsy / Q000706:statistics & numerical data
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone