title: Long-term colorectal-cancer mortality after adenoma removal.
abstract: BACKGROUND
  Although colonoscopic surveillance of patients after removal of adenomas is widely promoted, little is known about colorectal-cancer mortality among these patients.
  
  
  METHODS
  Using the linkage of the Cancer Registry and the Cause of Death Registry of Norway, we estimated colorectal-cancer mortality among patients who had undergone removal of colorectal adenomas during the period from 1993 through 2007. Patients were followed through 2011. We calculated standardized incidence-based mortality ratios (SMRs) using rates for the Norwegian population at large for comparison. Norwegian guidelines recommended colonoscopy after 10 years for patients with high-risk adenomas (adenomas with high-grade dysplasia, a villous component, or a size ≥10 mm) and after 5 years for patients with three or more adenomas; no surveillance was recommended for patients with low-risk adenomas. Polyp size and exact number were not available in the registry. We defined high-risk adenomas as multiple adenomas and adenomas with a villous component or high-grade dysplasia.
  
  
  RESULTS
  We identified 40,826 patients who had had colorectal adenomas removed. During a median follow-up of 7.7 years (maximum, 19.0), 1273 patients were given a diagnosis of colorectal cancer. A total of 398 deaths from colorectal cancer were expected and 383 were observed, for an SMR of 0.96 (95% confidence interval [CI], 0.87 to 1.06) among patients who had had adenomas removed. Colorectal-cancer mortality was increased among patients with high-risk adenomas (expected deaths, 209; observed deaths, 242; SMR, 1.16; 95% CI, 1.02 to 1.31), but it was reduced among patients with low-risk adenomas (expected deaths, 189; observed deaths, 141; SMR, 0.75; 95% CI, 0.63 to 0.88).
  
  
  CONCLUSIONS
  After a median of 7.7 years of follow-up, colorectal-cancer mortality was lower among patients who had had low-risk adenomas removed and moderately higher among those who had had high-risk adenomas removed, as compared with the general population. (Funded by the Norwegian Cancer Society and others.).
authors.affiliation: From the Department of Health Management and Health Economics, University of Oslo, Oslo (M.L., M.K., G.H., H.-O.A., M.B.), Department of Transplantation Medicine, Oslo University Hospital, Oslo (M.L., M.B.), Cancer Registry of Norway, Oslo (G.H.), Department of Research and Development, Telemark Hospital, Skien (M.K., G.H.), and Department of Medicine, Sørlandet Hospital Kristiansand, Kristiansand (Ø.H., M.B.) - all in Norway; the Department of Epidemiology, Harvard School of Public Health, Boston (M.L., M.K., Ø.H., H.-O.A., M.B.); and the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm (H.-O.A.).
authors.forename: Magnus
authors.initials: M
authors.lastname: Løberg
authors.forename: Mette
authors.initials: M
authors.lastname: Kalager
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Holme
authors.forename: Geir
authors.initials: G
authors.lastname: Hoff
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Adami
authors.forename: Michael
authors.initials: M
authors.lastname: Bretthauer
mesh_terms: D000236:Adenoma / Q000401:mortality / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000517:prevention & control / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009664:Norway / Q000453:epidemiology; D012042:Registries; D012306:Risk