title: Venous thromboembolism in patients with colorectal cancer: incidence and effect on survival.
abstract: OBJECTIVE
  To describe the incidence and outcomes associated with venous thromboembolism (VTE) among patients with colorectal cancer.
  
  
  METHODS
  This was a retrospective analysis of all colorectal cancer patients diagnosed in California between 1993 and 1995 and 1997 to 1999. Principal outcomes were incident symptomatic VTE events and death. Associations between specific risk factors and principal outcomes were analyzed using Cox proportional hazards models.
  
  
  RESULTS
  Among 68,142 colorectal cancer patients, 50% were women, mean age was 70 +/- 15 years, and approximately 70% underwent a major operation. The 2-year cumulative incidence of VTE was 2,100 patients (3.1%), with an incidence rate that decreased significantly over time from 5.0% (events/100 patient-years) in months 0 to 6 to 1.4% during months 7 to 12 to 0.6% during the second year. Significant predictors of VTE included metastatic stage (hazard ratio [HR] = 3.2; 95% CI, 2.8 to 3.8) and three or more comorbid conditions (HR = 2.0; 95% CI, 1.7 to 2.3). The risk of VTE was significantly reduced among Asians/Pacific Islanders (HR = 0.4; 95% CI, 0.3 to 0.5.) and patients who underwent an abdominal operation (HR = 0.4; 95% CI, 0.3 to 0.4). In risk-adjusted models, VTE was a significant predictor of death within 1 year of cancer diagnosis among patients with local- (HR = 1.8; 95% CI, 1.4 to 2.3) or regional-stage disease (HR = 1.5; 95% CI, 1.3 to 1.8) but not among patients with metastatic disease (HR = 1.1; 95% CI, 1.0 to 1.2).
  
  
  CONCLUSIONS
  The incidence of VTE among colorectal cancer patients was highest in the first 6 months after diagnosis and decreased rapidly thereafter. Metastatic disease and the number of medical comorbidities were the strongest predictors of VTE. Incident VTE reduced survival among patients with local or regional disease, suggesting that, in these patients, VTE may reflect the presence of a biologically more aggressive cancer.
authors.affiliation: Division of Hematology and Oncology, Department of Internal Medicine, University of California, Davis, Sacramento, CA 95817, USA.
authors.forename: Allison
authors.initials: A
authors.lastname: Alcalay
authors.forename: Ted
authors.initials: T
authors.lastname: Wun
authors.forename: Vijay
authors.initials: V
authors.lastname: Khatri
authors.forename: Helen K
authors.initials: HK
authors.lastname: Chew
authors.forename: Danielle
authors.initials: D
authors.lastname: Harvey
authors.forename: Hong
authors.initials: H
authors.lastname: Zhou
authors.forename: Richard H
authors.initials: RH
authors.lastname: White
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002140:California / Q000453:epidemiology; D015179:Colorectal Neoplasms / Q000150:complications* / Q000401:mortality* / Q000628:therapy; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate; D013923:Thromboembolism / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D020246:Venous Thrombosis / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality