title: Prevalence of colorectal cancer in relatives of Iranian patients diagnosed with colorectal cancer.
abstract: BACKGROUND
  A high rate of colorectal cancer occurrence is established in individuals with a positive family history of this type of cancer.
  
  
  OBJECTIVE
  The aim of this study was to investigate the prevalence of colorectal cancer in first degree and second degree relatives of colorectal cancer patients.
  
  
  METHODS
  Family medical histories of 489 first degree relatives of colorectal cancer patients were obtained by a questionnaire. 249 average risk patients with no family history of colorectal cancer were included as control patients.
  
  
  RESULTS
  In our study from a total of 489 case patients, 153 (31.3%) had at least one close relative affected by colon cancer. Case-control analysis showed an odd ratio of 3.1 (95% CI, 2.07 to 6.27) for one and 5.7 (CI, 2.39 to 13.56) for two affected relatives. Cases with a positive family history had a 3.006 times greater risk in developing colorectal cancer if a first degree relative was affected comparing with a 4.9 times greater risk if a second degree family member was diagnosed with colorectal cancer. Our study indicated a higher risk for developing colorectal cancer in male family relatives 50 years and older. Rectal area was found the most tumor side affected in case and control patients.
  
  
  CONCLUSIONS
  First-degree relatives of patients with colorectal cancer had an increased risk of developing this type of cancer. The risk was greater when diagnosis was in male, elderly patients and other first-degree relatives were affected.
authors.affiliation: Research Center for Gastroenterology and Liver Disease, Shahid Beheshti University of Medical Science, Tehran, Iran. Nedafat20@yahoo.com
authors.forename: Seyed Reza
authors.initials: SR
authors.lastname: Fatemi
authors.forename: Fatemeh Nemati
authors.initials: FN
authors.lastname: Malek
authors.forename: Sepideh
authors.initials: S
authors.lastname: Shivarani
authors.forename: Mohsen
authors.initials: M
authors.lastname: Vahedi
authors.forename: Shohreh
authors.initials: S
authors.lastname: Almasi
authors.forename: Elham
authors.initials: E
authors.lastname: Maserat
authors.forename: Marjan
authors.initials: M
authors.lastname: Ebrahimi
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zali
mesh_terms: D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000208:ethnology / Q000235:genetics*; D005190:Family / Q000208:ethnology*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007492:Iran; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D011795:Surveys and Questionnaires