title: Time-dependent risk of developing distant metastasis in breast cancer patients according to treatment, age and tumour characteristics.
abstract: BACKGROUND
  Metastatic breast cancer is a severe condition without curative treatment. How relative and absolute risk of distant metastasis varies over time since diagnosis, as a function of treatment, age and tumour characteristics, has not been studied in detail.
  
  
  METHODS
  A total of 9514 women under the age of 75 when diagnosed with breast cancer in Stockholm and Gotland regions during 1990-2006 were followed up for metastasis (mean follow-up=5.7 years). Time-dependent development of distant metastasis was analysed using flexible parametric survival models and presented as hazard ratio (HR) and cumulative risk.
  
  
  RESULTS
  A total of 995 (10.4%) patients developed distant metastasis; the most common sites were skeleton (32.5%) and multiple sites (28.3%). Women younger than 50 years at diagnosis, with lymph node-positive, oestrogen receptor (ER)-negative, >20 mm tumours and treated only locally, had the highest risk of distant metastasis (0-5 years' cumulative risk =0.55; 95% confidence interval (CI): 0.47-0.64). Women older than 50 years at diagnosis, with ER-positive, lymph node-negative and ≤20-mm tumours, had the same and lowest cumulative risk of developing metastasis 0-5 and 5-10 years (cumulative risk=0.03; 95% CI: 0.02-0.04). In the period of 5-10 years after diagnosis, women with ER-positive, lymph node-positive and >20-mm tumours were at highest risk of distant recurrence. Women with ER-negative tumours showed a decline in risk during this period.
  
  
  CONCLUSIONS
  Our data show no support for discontinuation at 5 years of clinical follow-up in breast cancer patients and suggest further investigation on differential clinical follow-up for different subgroups of patients.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Colzani
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: A L V
authors.initials: AL
authors.lastname: Johansson
authors.affiliation: Department of Oncology, Radiumhemmet, Karolinska University Hospital, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Liljegren
authors.affiliation: Department of Oncology, Radiumhemmet, Karolinska University Hospital, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Foukakis
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Clements
authors.affiliation: Department of Clinical Science, Intervention and Technology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Adolfsson
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Hall
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Czene
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000473:pathology*; D012306:Risk; D013548:Sweden; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents