title: Blurry boundaries: do epithelial borderline lesions of the breast and ductal carcinoma in situ have similar rates of subsequent invasive cancer?
abstract: BACKGROUND
  The histology of epithelial "borderline lesions" of the breast, which have features in between atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS), is well described, but the clinical behavior is not. This study reports subsequent ipsilateral breast events (IBE) in patients with borderline lesions compared with those with DCIS.
  
  
  METHODS
  Patients undergoing breast-conserving surgery for borderline lesions or DCIS from 1997 to 2010 were identified from a prospective database. IBE was defined as the diagnosis of subsequent ipsilateral DCIS or invasive ductal carcinoma.
  
  
  RESULTS
  A total of 143 borderline-lesion patients and 2,328 DCIS patients were identified. Median follow-up was 2.9 and 4.4 years, respectively. 7 borderline-lesion and 172 DCIS patients experienced an IBE. 5 year IBE rates were 7.7 % for borderline lesions and 7.2 % for DCIS (p = .80). 5 year invasive IBE rates were 6.5 and 2.8 %, respectively (p = .25). Similarly, when analyses were restricted to patients who did not receive radiotherapy, or endocrine therapy, or both, borderline-lesion and DCIS patients did not demonstrate statistically significant differences in rates of IBE or invasive IBE.
  
  
  CONCLUSIONS
  When compared with DCIS, borderline lesions do not demonstrate lower rates of IBE or invasive IBE. Despite "borderline" histology, a 5 year IBE rate of 7.7 % and an invasive IBE rate of 6.5 % suggest that the risk of future carcinoma is significant and similar to that of DCIS.
authors.affiliation: Breast Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Daniel X
authors.initials: DX
authors.lastname: Choi
authors.forename: Anne A
authors.initials: AA
authors.lastname: Eaton
authors.forename: Cristina
authors.initials: C
authors.lastname: Olcese
authors.forename: Sujata
authors.initials: S
authors.lastname: Patil
authors.forename: Monica
authors.initials: M
authors.lastname: Morrow
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Van Zee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D018270:Carcinoma, Ductal, Breast / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D018275:Carcinoma, Lobular / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006965:Hyperplasia / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D015996:Survival Rate; D055815:Young Adult