Background and aims: A family history of colorectal cancer is considered an independent risk factor for advanced neoplasia at colonoscopy. The expected outcome for screening colonoscopy in patients with a family history is not well established in all populations.
Methods: We designed a large, prospective study of an unselected population in San Diego, California to assess the impact of a family history of colorectal cancer on the prevalence of advanced neoplasia on screening colonoscopy.
Results: We evaluated 6,905 consecutive patients referred for colonoscopy between January 2005 and December 2006. Of the 4,967 who met the inclusion criteria, the mean age was 58.8 and consisted of 58.6% women. Overall 930 (18.7%) had neoplasia and 249 (5%) had advanced neoplasia, eight (0.16%) of which were cancer. The 4,967 patients were divided into 643 with and 4,324 without a family history of colorectal cancer. Of the 643 patients with a family history, 38 (5.9%) had advanced neoplasia, one of which was cancer. Of the 4,324 patients without a family history, 211 (4.9%) had advanced neoplasia including seven cancers. The relative risk for finding advanced neoplasia in patients with a single affected first degree relative was 1.21 (95% CI, 0.87-1.69; P = 0.31).
Conclusions: A family history of one first-degree relative with colorectal cancer did not predict a significantly higher prevalence of advanced neoplasia at screening colonoscopy in this Southwestern cohort.