title: Brain-only metastatic breast cancer is a distinct clinical entity characterised by favourable median overall survival time and a high rate of long-term survivors.
abstract: BACKGROUND
  The clinical course of breast cancer patients with brain metastases (BM) as only metastatic site (brain-only metastatic breast cancer (BO-MBC)) has been insufficiently explored.
  
  
  METHODS
  All breast cancer patients with BM treated at our institution between 1990 and 2011 were identified. For each patient, full information on follow-up and administered therapies was mandatory for inclusion. Oestrogen receptor, progesterone receptor and Her2 status were determined according to standard protocols. Statistical analyses including computation of survival probabilities was performed.
  
  
  RESULTS
  In total, 222 female patients (26% luminal; 47% Her2; 27% triple negative) with BM of MBC were included in this study. In all, 38/222 (17%) BM patients did not develop extracranial metastases (ECM) during their disease course and were classified as BO-MBC. Brain-only-MBC was not associated with breast cancer subtype or number of BM. The median overall survival of BO-MBC patients was 11 months (range 0-69) and was significantly longer than in patients with BM and ECM (6 months, range 0-104; P=0.007). In all, 7/38 (18%) BO-MBC patients had long-term survival of >3 years after diagnosis of BM and long-term survival was significantly more common in BO-MBC patients as compared with BM patients with ECM (P<0.001).
  
  
  CONCLUSIONS
  Brain-only metastatic behaviour occurs in around 17% of breast cancer with BM and is not associated with breast cancer subtype. Exploitation of all multimodal treatment options is warranted in BO-MBC patients, as these patients have favourable prognosis and long-term survival is not uncommon.
authors.affiliation: Institute of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: A S
authors.initials: AS
authors.lastname: Berghoff
authors.forename: Z
authors.initials: Z
authors.lastname: Bago-Horvath
authors.forename: A
authors.initials: A
authors.lastname: Ilhan-Mutlu
authors.forename: M
authors.initials: M
authors.lastname: Magerle
authors.forename: K
authors.initials: K
authors.lastname: Dieckmann
authors.forename: C
authors.initials: C
authors.lastname: Marosi
authors.forename: P
authors.initials: P
authors.lastname: Birner
authors.forename: G
authors.initials: G
authors.lastname: Widhalm
authors.forename: G G
authors.initials: GG
authors.lastname: Steger
authors.forename: C C
authors.initials: CC
authors.lastname: Zielinski
authors.forename: R
authors.initials: R
authors.lastname: Bartsch
authors.forename: M
authors.initials: M
authors.lastname: Preusser
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000556:secondary*; D001943:Breast Neoplasms / Q000473:pathology*; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011379:Prognosis; D015996:Survival Rate; D017741:Survivors