title: Risk of cancer following primary total hip replacement or primary resurfacing arthroplasty of the hip: a retrospective cohort study in Scotland.
abstract: BACKGROUND
  Release and dispersion of particles arising from corrosion and wear of total hip arthroplasty (THA) components has raised concerns about a possible increased risk of cancer. Concerns have been heightened by a recent revival in the use of metal-on-metal (MoM) hip prostheses.
  
  
  METHODS
  From a linked database of hospital discharge, cancer registration, and mortality records, we selected a cohort of patients who underwent primary THA (1990-2009) or primary resurfacing arthroplasty (mainly 2000-2009) in Scotland, with follow-up to the end of 2010. Available operation codes did not enable us to distinguish MoM THAs. Indirectly standardised incidence ratios (SIRs) were calculated for selected cancers with standardisation for age, sex, deprivation, and calendar period.
  
  
  RESULTS
  The study cohort included 71 990 patients yielding 547 001 person-years at risk (PYAR) and 13 946 cancers diagnosed during follow-up. For the total period of observation combined, the risks of all cancers (SIR: 1.05; 95% CI: confidence interval 1.04-1.07), prostate cancer (SIR: 1.07; 95% CI: 1.01-1.14), and multiple myeloma (SIR: 1.22; 95% CI: 1.06-1.41) were increased. These modest increases in risk emerged in the context of effectively multiple tests of statistical significance, and may reflect inadequate adjustment for confounding factors. For 1317 patients undergoing primary resurfacing arthroplasty between 2000 and 2009 (PYAR=5698), the SIR for all cancers (n=39) was 1.23 (95% CI: 0.87-1.68).
  
  
  CONCLUSIONS
  In the context of previous research, these results do not suggest a major cause for concern. However, the duration of follow-up of patients receiving recently introduced, new-generation MoM prostheses is too short to rule out a genuinely increased risk of cancer entirely.
authors.affiliation: Information Services Division, NHS National Services Scotland, Gyle Square, 1 South Gyle Crescent, Edinburgh EH12 9EB, UK. David.Brewster@nhs.net
authors.forename: D H
authors.initials: DH
authors.lastname: Brewster
authors.forename: D L
authors.initials: DL
authors.lastname: Stockton
authors.forename: A
authors.initials: A
authors.lastname: Reekie
authors.forename: G P
authors.initials: GP
authors.lastname: Ashcroft
authors.forename: C R
authors.initials: CR
authors.lastname: Howie
authors.forename: D E
authors.initials: DE
authors.lastname: Porter
authors.forename: R J
authors.initials: RJ
authors.lastname: Black
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008670:Metals / Q000009:adverse effects*; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D012189:Retrospective Studies; D012306:Risk; D012606:Scotland / Q000453:epidemiology
chemical_list: D008670:Metals
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