Prevalence of Colorectal Cancer in Relatives of Iranian Patients Diagnosed with Colorectal Cancer

Background: A high rate of colorectal cancer occurrence is established in individuals with a positive familyhistory of this type of cancer.
Objectives: The aim of this study was to investigate the prevalence of colorectalcancer in first degree and second degree relatives of colorectal cancer patients.
Methods: Family medical historiesof 489 first degree relatives of colorectal cancer patients were obtained by a questionnaire. 249 average riskpatients with no family history of colorectal cancer were included as control patients.
Results: In our study froma total of 489 case patients, 153 (31.3%) had at least one close relative affected by colon cancer. Case-controlanalysis 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 affectedrelatives. Cases with a positive family history had a 3.006 times greater risk in developing colorectal cancer if afirst degree relative was affected comparing with a 4.898 time greater risk if a second degree family memberwas diagnosed with colorectal cancer .Our study indicated a higher risk for developing colorectal cancer in malefamily relatives 50 years and older. Rectal area was found the most tumor side affected in case and controlpatients.
Conclusion: First-degree relatives of patients with colorectal cancer had an increased risk of developingthis type of cancer. The risk was greater when diagnosis was in male, elderly patients and other first-degreerelatives were affected.