title: Patterns of care and survival after a cancer of unknown primary (CUP) diagnosis: A population-based nested cohort study in Australian Government Department of Veterans' Affairs clients.
abstract: BACKGROUND
  Little is known about patterns of care after a cancer of unknown primary (CUP) diagnosis.
  
  
  METHODS
  We performed a retrospective cohort study to describe and compare the treatment, health service use and survival of patients with CUP and metastatic cancer of known primary among 143,956 Australian Government Department of Veterans' Affairs clients, 2004-2007. We randomly matched clients with CUP (C809; n=252) with clients with a first diagnosis of metastatic solid cancer of known primary (n=980). We ascertained health services from the month of diagnosis up to 2 months post-diagnosis for consultations, hospitalizations and emergency department visits, and up to 1 year for treatment. We compared cancer treatments using conditional logistic regression; consultation rates using negative binomial regression; and survival using stratified Cox regression.
  
  
  RESULTS
  30% of CUP patients and 70% of patients with known primary received cancer treatment and the median survival was 37 days and 310 days respectively. CUP patients received fewer cancer medicines (odds ratio (OR)=0.54, 95% confidence interval (CI) 0.33-0.89) and less cancer-related surgery (OR=0.25, 95% CI 0.15-0.41); males with CUP received more radiation therapy (OR=2.88, 95% CI 1.69-4.91). CUP patients had more primary care consultations (incidence rate ratio (IRR)=1.25, 95% CI 1.11-1.41), emergency department visits (IRR=1.86, 95% CI 1.50-2.31) and hospitalizations (IRR=1.18, 95% CI 1.03-1.35), and a higher risk of death within 30 days (hazard ratio=3.30, 95% CI 1.69-6.44).
  
  
  CONCLUSIONS
  Patients with CUP receive less treatment but use more health services, which may reflect underlying patient and disease characteristics.
authors.affiliation: Faculty of Pharmacy, University of Sydney, NSW, Australia.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Schaffer
authors.affiliation: Faculty of Pharmacy, University of Sydney, NSW, Australia; School of Public Health, University of Sydney, NSW, Australia.
authors.forename: Sallie-Anne
authors.initials: SA
authors.lastname: Pearson
authors.affiliation: National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australia; Cancer Epidemiology and Services Research, Sydney School of Public Health, Sydney Medical School, University of Sydney, NSW, Australia.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Dobbins
authors.affiliation: Adult Cancer Program, Prince of Wales Clinical School, University of New South Wales, NSW 2052, Australia.
authors.forename: Chuang C
authors.initials: CC
authors.lastname: Er
authors.affiliation: Adult Cancer Program, Prince of Wales Clinical School, University of New South Wales, NSW 2052, Australia.
authors.forename: Robyn L
authors.initials: RL
authors.lastname: Ward
authors.affiliation: Adult Cancer Program, Prince of Wales Clinical School, University of New South Wales, NSW 2052, Australia. Electronic address: claire.vajdic@unsw.edu.au.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Vajdic
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001315:Australia; D015331:Cohort Studies; D005260:Female; D006076:Government; D006296:Health Services / Q000706:statistics & numerical data; D006801:Humans; D016015:Logistic Models; D008297:Male; D009382:Neoplasms, Unknown Primary / Q000401:mortality / Q000628:therapy*; D016017:Odds Ratio; D012189:Retrospective Studies; D014728:Veterans
keywords: Cancer of unknown primary; Cohort; Epidemiology; Health services; Treatment