title: Prognosis of metastatic breast cancer: are there differences between patients with de novo and recurrent metastatic breast cancer?
abstract: BACKGROUND
  We aimed to determine the prognostic impact of time between primary breast cancer and diagnosis of distant metastasis (metastatic-free interval, MFI) on the survival of metastatic breast cancer patients.
  
  
  METHODS
  Consecutive patients diagnosed with metastatic breast cancer in 2007-2009 in eight hospitals in the Southeast of the Netherlands were included and categorised based on MFI. Survival curves were estimated using the Kaplan-Meier method. Cox proportional hazards model was used to determine the prognostic impact of de novo metastatic breast cancer vs recurrent metastatic breast cancer (MFI ⩽24 months and >24 months), adjusted for age, hormone receptor and HER2 status, initial site of metastasis and use of prior (neo)adjuvant systemic therapy.
  
  
  RESULTS
  Eight hundred and fifteen patients were included and divided in three subgroups based on MFI; 154 patients with de novo metastatic breast cancer, 176 patients with MFI <24 months and 485 patients with MFI >24 months. Patients with de novo metastatic breast cancer had a prolonged survival compared with patients with recurrent metastatic breast cancer with MFI <24 months (median 29.4 vs 9.1 months, P<0.0001), but no difference in survival compared with patients with recurrent metastatic breast cancer with MFI >24 months (median, 29.4 vs 27.9 months, P=0.73). Adjusting for other prognostic factors, patients with MFI <24 months had increased mortality risk (hazard ratio 1.97, 95% CI 1.49-2.60, P<0.0001) compared with patients with de novo metastatic breast cancer. When comparing recurrent metastatic breast cancer with MFI >24 months with de novo metastatic breast cancer no significant difference in mortality risk was found. The association between MFI and survival was seen irrespective of use of (neo)adjuvant systemic therapy.
  
  
  CONCLUSIONS
  Patients with de novo metastatic breast cancer had a significantly better outcome when compared with patients with MFI <24 months, irrespective of the use of prior adjuvant systemic therapy in the latter group. However, compared with patients with MFI >24 months, patients with de novo metastatic breast cancer had similar outcome.
authors.affiliation: 1] GROW- School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands [2] Department of Internal Medicine, Máxima Medical Centre, Veldhoven, The Netherlands.
authors.forename: D J A
authors.initials: DJ
authors.lastname: Lobbezoo
authors.affiliation: GROW- School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: R J W
authors.initials: RJ
authors.lastname: van Kampen
authors.affiliation: 1] GROW- School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands [2] Department of Research, Comprehensive Cancer Centre, Eindhoven, The Netherlands.
authors.forename: A C
authors.initials: AC
authors.lastname: Voogd
authors.affiliation: Department of Internal Medicine, Máxima Medical Centre, Veldhoven, The Netherlands.
authors.forename: M W
authors.initials: MW
authors.lastname: Dercksen
authors.affiliation: Department of Internal Medicine, Atrium Medical Centre Parkstad, Heerlen, The Netherlands.
authors.forename: F
authors.initials: F
authors.lastname: van den Berkmortel
authors.affiliation: Department of Internal Medicine, Jeroen Bosch Hospital, Den Bosch, The Netherlands.
authors.forename: T J
authors.initials: TJ
authors.lastname: Smilde
authors.affiliation: Department of Internal Medicine, VieCuri Medical Centre, Venlo, The Netherlands.
authors.forename: A J
authors.initials: AJ
authors.lastname: van de Wouw
authors.affiliation: Department of Internal Medicine, Orbis Medical Centre, Sittard, The Netherlands.
authors.forename: F P J
authors.initials: FP
authors.lastname: Peters
authors.affiliation: Department of Internal Medicine, St Elisabeth Hospital, Tilburg, The Netherlands.
authors.forename: J M G H
authors.initials: JM
authors.lastname: van Riel
authors.affiliation: Department of Internal Medicine, St Jans Hospital, Weert, The Netherlands.
authors.forename: N A J B
authors.initials: NA
authors.lastname: Peters
authors.affiliation: GROW- School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: de Boer
authors.affiliation: Department for Health Evidence, Radboud university medical centre, Nijmegen, The Netherlands.
authors.forename: P G M
authors.initials: PG
authors.lastname: Peer
authors.affiliation: GROW- School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: V C G
authors.initials: VC
authors.lastname: Tjan-Heijnen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D009367:Neoplasm Staging; D011379:Prognosis; D015996:Survival Rate