title: Colon and rectal cancer survival by tumor location and microsatellite instability: the Colon Cancer Family Registry.
abstract: BACKGROUND
  Cancers in the proximal colon, distal colon, and rectum are frequently studied together; however, there are biological differences in cancers across these sites, particularly in the prevalence of microsatellite instability.
  
  
  OBJECTIVE
  We assessed the differences in survival by colon or rectal cancer site, considering the contribution of microsatellite instability to such differences.
  
  
  METHODS
  This is a population-based prospective cohort study for cancer survival.
  
  
  METHODS
  This study was conducted within the Colon Cancer Family Registry, an international consortium. Participants were identified from population-based cancer registries in the United States, Canada, and Australia.
  
  
  METHODS
  Information on tumor site, microsatellite instability, and survival after diagnosis was available for 3284 men and women diagnosed with incident invasive colon or rectal cancer between 1997 and 2002, with ages at diagnosis ranging from 18 to 74.
  
  
  METHODS
  Cox regression was used to calculate hazard ratios for the association between all-cause mortality and tumor location, overall and by microsatellite instability status.
  
  
  RESULTS
  Distal colon (HR, 0.59; 95% CI, 0.49-0.71) and rectal cancers (HR, 0.68; 95% CI, 0.57-0.81) were associated with lower mortality than proximal colon cancer overall. Compared specifically with patients with proximal colon cancer exhibiting no/low microsatellite instability, patients with distal colon and rectal cancers experienced lower mortality, regardless of microsatellite instability status; patients with proximal colon cancer exhibiting high microsatellite instability had the lowest mortality.
  
  
  CONCLUSIONS
  Study limitations include the absence of stage at diagnosis and cause-of-death information for all but a subset of study participants. Some patient groups defined jointly by tumor site and microsatellite instability status are subject to small numbers.
  
  
  CONCLUSIONS
  Proximal colon cancer survival differs from survival for distal colon and rectal cancer in a manner apparently dependent on microsatellite instability status. These findings support the premise that proximal colon, distal colon, and rectal cancers are clinicopathologically distinct.
authors.affiliation: Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA. aphipps@fhcrc.org
authors.forename: Amanda I
authors.initials: AI
authors.lastname: Phipps
authors.forename: Noralane M
authors.initials: NM
authors.lastname: Lindor
authors.forename: Mark A
authors.initials: MA
authors.lastname: Jenkins
authors.forename: John A
authors.initials: JA
authors.lastname: Baron
authors.forename: Aung Ko
authors.initials: AK
authors.lastname: Win
authors.forename: Steven
authors.initials: S
authors.lastname: Gallinger
authors.forename: Robert
authors.initials: R
authors.lastname: Gryfe
authors.forename: Polly A
authors.initials: PA
authors.lastname: Newcomb
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D014408:Biomarkers, Tumor / Q000235:genetics*; D002170:Canada / Q000453:epidemiology; D003106:Colon / Q000473:pathology; D003110:Colonic Neoplasms / Q000235:genetics / Q000401:mortality*; D018899:CpG Islands; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D011446:Prospective Studies; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D012004:Rectal Neoplasms / Q000235:genetics / Q000401:mortality*; D012007:Rectum / Q000473:pathology; D012042:Registries; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D048493:Proto-Oncogene Proteins B-raf