title: Microinvasive breast cancer: ER, PR, and HER-2/neu status and clinical outcomes after breast-conserving therapy or mastectomy.
abstract: BACKGROUND
  Contemporary clinical outcomes of microinvasive breast cancer (MIBC), defined as no focus >1 mm, are not well characterized. We document the immunophenotype, incidence of axillary metastases, and rate of recurrence in a well-defined case series.
  
  
  METHODS
  We reviewed 83 consecutive patients with MIBC from 1997 to 2005. Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2/neu) receptor status were assessed. The cumulative incidence of local recurrence (LR) and nodal/distant recurrence was calculated. Predictors of recurrence were identified and effect estimates determined.
  
  
  RESULTS
  Fifty-two patients (63%) underwent breast-conserving therapy (BCT) and 31 (37%) underwent mastectomy. Sixty-one percent had ER-positive disease and 49% had HER-2/neu-positive disease. Three (4%) of 68 patients with sentinel node mapping or axillary dissection had single node micrometastases, and none had macrometastases or multiple nodes involved. Median follow-up was 6.4 years, with 6 LRs, 2 regional nodal recurrences, and 2 concurrent local/distant recurrences. The 5-year cumulative incidence of recurrence (local, nodal, or distant) was 5.3% (95% confidence interval [CI] 2.0-13.4) for all patients, and among BCT patients, the 5-year cumulative incidence of LR was 4.2% (95% CI 0.7-12.7). HER-2/neu overexpression was not associated with recurrence (P = 0.46). Close/positive margins (≤2 mm) were significantly associated with an increased risk of LR after BCT or mastectomy (hazard ratio 8.8; 95% CI 1.6-48.8; P = 0.003).
  
  
  CONCLUSIONS
  MIBC has a favorable prognosis, and HER-2/neu overexpression, although highly prevalent, is not significantly associated with recurrence. Axillary metastases at diagnosis are small and infrequent. The cumulative incidence of LR after BCT is acceptable; however, our data confirm that negative margins (>2 mm) are required for optimal BCT outcomes.
authors.affiliation: Department of Radiation Oncology, Brigham & Women's Hospital/Dana-Farber Cancer Institute, Boston, MA, USA.
authors.forename: Danielle N
authors.initials: DN
authors.lastname: Margalit
authors.forename: Meera
authors.initials: M
authors.lastname: Sreedhara
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Chen
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Catalano
authors.forename: Paul L
authors.initials: PL
authors.lastname: Nguyen
authors.forename: Mehra
authors.initials: M
authors.lastname: Golshan
authors.forename: Beth A
authors.initials: BA
authors.lastname: Overmoyer
authors.forename: Jay R
authors.initials: JR
authors.lastname: Harris
authors.forename: Jane E
authors.initials: JE
authors.lastname: Brock
mesh_terms: D000328:Adult; D001365:Axilla; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008408:Mastectomy; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D009367:Neoplasm Staging; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D015996:Survival Rate
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone