title: Comparison of treatment and outcome information between a clinical trial and the National Cancer Data Repository.
abstract: BACKGROUND
  Clinical trials are important but many factors limit their success, including the costs of long-term follow-up and participants often not being representative of the general population. The National Cancer Data Repository (NCDR) contains data about patients with cancer in England that may help overcome some of these problems. This study compared treatment and outcome information between the Medical Research Council Conventional versus Laparoscopic-Assisted Surgery in Colorectal Cancer (CLASICC) trial and the NCDR.
  
  
  METHODS
  Participants in the CLASICC trial were identified in the NCDR, and management and outcome data were compared. Data on all surgically treated English patients with colorectal cancer were extracted from the NCDR and compared with those of CLASICC participants.
  
  
  RESULTS
  Survival and treatment data for those in the CLASICC trial were available in the NCDR for 98·9 and 95·8 per cent of patients respectively. There was agreement in operation type for 86·1 per cent of patients but surgical approach coding was poor, with only 58·4 per cent of laparoscopic procedures coded in the NCDR. There was no significant difference in survival calculated from either data set. Surgical information was available in the NCDR for 19 of 20 trial participants with missing data. The trial population was younger (P < 0·001), of better socioeconomic status (P = 0·001) and with earlier disease (P < 0·001) than the general surgically treated colorectal cancer population. Rectal cancer survival was similar, but 5-year survival after treatment of colonic cancer was significantly better in the trial than in the national data: 57·1 (95 per cent confidence interval 51·5 to 62·3) versus 49·8 (49·3 to 50·2) per cent respectively.
  
  
  CONCLUSIONS
  The National Cancer Data Repository demonstrates potential for informing clinical trials, but limitations prevent full intention-to-treat analyses.
authors.affiliation: Colorectal Cancer Epidemiology Group, Centre for Epidemiology and Biostatistics, University of Leeds, St James's University Hospital, Leeds, UK. eva.morris@nycris.leedsth.nhs.uk
authors.forename: E J A
authors.initials: EJ
authors.lastname: Morris
authors.forename: C
authors.initials: C
authors.lastname: Jordan
authors.forename: J D
authors.initials: JD
authors.lastname: Thomas
authors.forename: M
authors.initials: M
authors.lastname: Cooper
authors.forename: J M
authors.initials: JM
authors.lastname: Brown
authors.forename: H
authors.initials: H
authors.lastname: Thorpe
authors.forename: D
authors.initials: D
authors.lastname: Cameron
authors.forename: D
authors.initials: D
authors.lastname: Forman
authors.forename: D
authors.initials: D
authors.lastname: Jayne
authors.forename: P
authors.initials: P
authors.lastname: Quirke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002986:Clinical Trials as Topic; D003110:Colonic Neoplasms / Q000401:mortality / Q000601:surgery*; D005260:Female; D006801:Humans; D007223:Infant; D010535:Laparoscopy / Q000401:mortality / Q000706:statistics & numerical data; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000401:mortality / Q000601:surgery*; D012042:Registries; D012959:Socioeconomic Factors; D016896:Treatment Outcome; D006113:United Kingdom