title: Is inflammatory bowel disease an important risk factor among older persons with colorectal cancer in the United States? A population-based case-control study.
abstract: BACKGROUND
  While ulcerative colitis (UC) and Crohn's disease (CD) are thought to predispose to colorectal cancer (CRC), the association has not been well studied in an older population.
  
  
  OBJECTIVE
  The objective of our study was to evaluate the association of ulcerative colitis and Crohn's disease and colorectal cancer in a population-based, case-control study. We also wished to estimate the incidence rates of colorectal cancer among older individuals with UC/CD.
  
  
  METHODS
  All cases of colorectal cancer in persons 67 and older in the SEER catchment area and in the Medicare claims database were compared with cancer-free controls residing in the same geographic area. We used multivariable logistic regression models adjusted for demographic and other factors.
  
  
  RESULTS
  We identified 47,543 cases of CRC and 142,273 controls. We found a modest association between UC and CRC (OR 1.93; 95% CI 1.54-2.49; P-value<0.001) and a significant, albeit modest, association between CD and CRC (OR 1.45; 95% CI 1.08-1.91; P-value 0.01). We found the incidence of CRC to be 8.2 per 10,000 person-years (95% CI 6.5-10.1/10,000 person-years) among those with UC/CD, and 6.1 per 10,000 person-years (95% CI 4.6-7.8/10,000 person-years) among those without UC/CD, resulting in an incidence rate ratio of 1.34.
  
  
  CONCLUSIONS
  Among older persons ulcerative colitis and Crohn's disease are modest risk factors for CRC, and the incidence rate ratio for CRC is modest, suggesting that risk of CRC in patients with IBD may be lower than previously thought.
authors.affiliation: Section of Gastroenterology, Department of Medicine, VA Medical Center and University of Minnesota, Gastroenterology Section 111-D, 1- Veterans Drive, Minneapolis, MN 55417, USA. shaukat@umn.edu
authors.forename: Aasma
authors.initials: A
authors.lastname: Shaukat
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Virnig
authors.forename: Nadim I
authors.initials: NI
authors.lastname: Salfiti
authors.forename: David H
authors.initials: DH
authors.lastname: Howard
authors.forename: Shanthi V
authors.initials: SV
authors.lastname: Sitaraman
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Liff
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000453:epidemiology*; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology