title: Can calcium chemoprevention of adenoma recurrence substitute or serve as an adjunct for colonoscopic surveillance?
abstract: OBJECTIVE
  The aim of this study was to examine the potential cost-effectiveness of calcium chemoprevention post-polypectomy as a substitute or adjunct for surveillance.
  
  
  METHODS
  We constructed a Markov model of post-polypectomy adenoma recurrence and colorectal cancer (CRC) development, calibrated to data from prospective chemoprevention trials of fiber, calcium, antioxidants, and aspirin. We modeled four scenarios for 50-year-old patients immediately after polypectomy: (i) natural history with no further intervention; (ii) elemental calcium 1,200 mg/day from age 50-80; (iii) surveillance colonoscopy from age 50-80 every 5 years, or 3 years for large adenoma; (iv) calcium + surveillance. Patients were followed up until age 100 or death.
  
  
  RESULTS
  Calcium was cost-effective compared to natural history ($49,900/life-year gained). However, surveillance was significantly more effective than calcium (18.729 versus 18.654 life-years/patient; 76 percent versus 14 percent reduction in CRC incidence) at an incremental cost of $15,900/life-year gained. Calcium + surveillance yielded a very small benefit (0.0003 incremental life-years/patient) compared with surveillance alone, at a substantial incremental cost of $3,090,000/life-year gained.
  
  
  CONCLUSIONS
  Post-polypectomy calcium chemoprevention is unlikely to be a reasonable substitute for surveillance. It may be cost-effective in patients unwilling or unable to undergo surveillance.
authors.affiliation: Department of Medicine, Division of Gastroenterology, University of Minnesota, 406 Harvard Street SE, MMC 36, Minneapolis, Minnesota 55455, USA. shaukat@umn.edu
authors.forename: Aasma
authors.initials: A
authors.lastname: Shaukat
authors.forename: Murtaza
authors.initials: M
authors.lastname: Parekh
authors.forename: Joseph
authors.initials: J
authors.lastname: Lipscomb
authors.forename: Uri
authors.initials: U
authors.lastname: Ladabaum