title: Mortality by stage for right- versus left-sided colon cancer: analysis of surveillance, epidemiology, and end results--Medicare data.
abstract: OBJECTIVE
  Recent studies have reported increased mortality for right-sided colon cancers but had limited adjustment for patient characteristics and conflicting results by stage. We examined the relationship between colon cancer location (right- v left-side) and 5-year mortality by stage.
  
  
  METHODS
  We identified Medicare beneficiaries from 1992 to 2005 with American Joint Commission on Cancer stages I to III primary adenocarcinoma of the colon who underwent surgery for curative intent through Surveillance, Epidemiology, and End Results (SEER) -Medicare data. Adjusted hazard ratios (HRs) and 95% CIs for predictors of all-cause 5-year mortality were obtained by using Cox proportional hazards regression.
  
  
  RESULTS
  Of 53,801 patients, 67% had right-sided colon cancer. Patients with right-sided cancer were more likely to be older, to be women, to be diagnosed with a more advanced stage, and to have more poorly differentiated tumors. Adjusted Cox regression showed no significant difference in mortality between right- and left-sided cancers for all stages combined (HR, 1.01; 95% CI, 0.98 to 1.04; P = .598) or for stage I cancers (HR, 0.95; 95% CI, 0.88 to 1.03; P = .211). Stage II right-sided cancers had lower mortality than left-sided cancers (HR, 0.92; 95% CI, 0.87 to 0.97; P = .001), and stage III right-sided cancers had higher mortality (HR, 1.12; 95% CI, 1.06 to 1.18; P < .001).
  
  
  CONCLUSIONS
  When analysis was adjusted for multiple patient, disease, comorbidity, and treatment variables, no overall difference in 5-year mortality was seen between right- and left-sided colon cancers. However, within stage II disease, right-sided cancers had lower mortality; within stage III, right-sided cancers had higher mortality.
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, WI, USA. jmw@medicine.wisc.edu
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Weiss
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Pfau
authors.forename: Erin S
authors.initials: ES
authors.lastname: O'Connor
authors.forename: Jonathan
authors.initials: J
authors.lastname: King
authors.forename: Noelle
authors.initials: N
authors.lastname: LoConte
authors.forename: Gregory
authors.initials: G
authors.lastname: Kennedy
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Smith
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000401:mortality* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D006278:Medicare; D009367:Neoplasm Staging; D018426:SEER Program; D014481:United States