title: Time to diagnosis and mortality in colorectal cancer: a cohort study in primary care.
abstract: BACKGROUND
  The relationship between the diagnostic interval and mortality from colorectal cancer (CRC) is unclear. This association was examined by taking account of important confounding factors at the time of first presentation of symptoms in primary care.
  
  
  METHODS
  A total of 268 patients with CRC were included in a prospective, population-based study in a Danish county. The diagnostic interval was defined as the time from first presentation of symptoms until diagnosis. We analysed patients separately according to the general practitioner's interpretation of symptoms. Logistic regression was used to estimate 3-year mortality odds ratios as a function of the diagnostic interval using restricted cubic splines and adjusting for tumour site, comorbidity, age, and sex.
  
  
  RESULTS
  In patients presenting with symptoms suggestive of cancer or any other serious illness, the risk of dying within 3 years decreased with diagnostic intervals up to 5 weeks and then increased (P=0.002). In patients presenting with vague symptoms, the association was reverse, although not statistically significant.
  
  
  CONCLUSIONS
  Detecting cancer in primary care is two sided: aimed at expediting ill patients while preventing healthy people from going to hospital. This likely explains the counterintuitive findings; but it does not explain the increasing mortality with longer diagnostic intervals. Thus, this study provides evidence for the hypothesis that the length of the diagnostic interval affects mortality in CRC patients.
authors.affiliation: The Research Unit for General Practice, Research Centre for Cancer Diagnosis in Primary Care, School of Public Health, Aarhus University, Bartholin Allé 2, DK-8000 Aarhus C, Denmark. mlt@alm.au.dk
authors.forename: M L
authors.initials: ML
authors.lastname: Tørring
authors.forename: M
authors.initials: M
authors.lastname: Frydenberg
authors.forename: R P
authors.initials: RP
authors.lastname: Hansen
authors.forename: F
authors.initials: F
authors.lastname: Olesen
authors.forename: W
authors.initials: W
authors.lastname: Hamilton
authors.forename: P
authors.initials: P
authors.lastname: Vedsted
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002277:Carcinoma / Q000175:diagnosis* / Q000453:epidemiology / Q000401:mortality*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care / Q000706:statistics & numerical data*; D012042:Registries; D016019:Survival Analysis; D013997:Time Factors; D055815:Young Adult