title: Excess mortality after curative surgery for colorectal cancer changes over time and differs for patients with colon versus rectal cancer.
abstract: BACKGROUND
  Improved management of colorectal cancer patients has resulted in better five-year survival for rectal cancer compared with colon cancer. We compared excess mortality rates in various time intervals after surgery in patients with colon and rectal cancer.
  
  
  METHODS
  We analysed all patients with curative resection of colorectal cancers reported in the Cancer Registry of Norway before (1994-1996) and after (2001-2003) national treatment guidelines were introduced. Excess mortality was analysed in different postoperative time intervals within the five-year follow-up periods for patients treated in 1994-1996 vs. 2001-2003.
  
  
  RESULTS
  A total of 11 437 patients that underwent curative resection were included. For patients treated from 1994 to 1996, excess mortality was similar in colon and rectal cancer patients in all time intervals. For those treated from 2001 to 2003, excess mortality was significantly lower in rectal cancer patients than in colon cancer patients perioperatively (in the first 60 days: excess mortality ratio = 0.46, p = 0.007) and during the first two postoperative years (2-12 months: excess mortality ratio = 0.54, p = 0.010; 1-2 years: excess mortality ratio = 0.60, p = 0.009). Excess mortality in rectal cancer patients was significantly greater than in colon cancer patients 4-5 years postoperatively (excess mortality ratio = 2.18, p = 0.003).
  
  
  CONCLUSIONS
  Excess mortality for colon and rectal cancer changed substantially after the introduction of national treatment guidelines. Short-term excess mortality rates was higher in colon cancer compared to rectal cancer for patients treated in 2001-2003, while excess mortality rates for rectal cancer patients was significantly higher later in the follow-up period. This suggests that future research should focus on these differences of excess mortality in patients curatively treated for cancer of the colon and rectum.
authors.affiliation: Department of Surgery, Stavanger University Hospital, Stavanger, Norway. nedreboe@me.com
authors.forename: Bjørn Steinar
authors.initials: BS
authors.lastname: Nedrebø
authors.forename: Kjetil
authors.initials: K
authors.lastname: Søreide
authors.forename: Morten Tandberg
authors.initials: MT
authors.lastname: Eriksen
authors.forename: Jan Terje
authors.initials: JT
authors.lastname: Kvaløy
authors.forename: Jon Arne
authors.initials: JA
authors.lastname: Søreide
authors.forename: Hartwig
authors.initials: H
authors.lastname: Kørner
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality* / Q000601:surgery; D000368:Aged; D003110:Colonic Neoplasms / Q000401:mortality* / Q000601:surgery; D015179:Colorectal Neoplasms / Q000401:mortality / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D009026:Mortality / Q000639:trends; D009664:Norway / Q000453:epidemiology; D017410:Practice Guidelines as Topic; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000401:mortality* / Q000601:surgery