title: South African National Cancer Registry: Effect of withheld data from private health systems on cancer incidence estimates.
abstract: BACKGROUND
  The National Cancer Registry (NCR) was established as a pathology-based cancer reporting system. From 2005 to 2007, private health laboratories withheld cancer reports owing to concerns regarding voluntary sharing of patient data.
  
  
  OBJECTIVE
  To estimate the impact of under-reported cancer data from private health laboratories.
  
  
  METHODS
  A linear regression analysis was conducted to project expected cancer cases for 2005-2007. Differences between actual and projected figures were calculated to estimate percentage under-reporting.
  
  
  RESULTS
  The projected NCR case total varied from 53,407 (3.8% net increase from actual cases reported) in 2005 to 54,823 (3.7% net increase) in 2007. The projected number of reported cases from private laboratories in 2005 was 26,359 (19.7% net increase from actual cases reported), 27,012 (18.8% net increase) in 2006 and 27,666 (28.4% net increase) in 2007.
  
  
  CONCLUSIONS
  While private healthcare reporting decreased by 28% from 2005 to 2007, this represented a minimal impact on overall cancer reporting (net decrease of <4%).
authors.affiliation: Cancer Epidemiology Research Group, National Cancer Registry, National Health Laboratory Service, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. elvira.singh@nioh.nhls.ac.za.
authors.forename: E
authors.initials: E
authors.lastname: Singh
authors.forename: J M
authors.initials: JM
authors.lastname: Underwood
authors.forename: C
authors.initials: C
authors.lastname: Nattey
authors.forename: C
authors.initials: C
authors.lastname: Babb
authors.forename: M
authors.initials: M
authors.lastname: Sengayi
authors.forename: P
authors.initials: P
authors.lastname: Kellett
mesh_terms: D000368:Aged; D057286:Electronic Health Records / Q000458:organization & administration*; D006801:Humans; D015994:Incidence; D009369:Neoplasms / Q000453:epidemiology*; D012042:Registries / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D013019:South Africa / Q000453:epidemiology