Risk factors for advanced sporadic colorectal neoplasia in persons younger than age 50

Colorectal cancer (CRC) screening is recommended for average-risk adults beginning at age 50. However, 7% of CRC occurs in persons younger than age 50, a group for which risk factors are not well defined. We sought to determine whether a retrospective case-control study could identify risk factors for sporadic CRC and advanced adenomatous polyps (together known as sporadic colorectal neoplasia [CRN]).

Using the cancer registry, medical records, and endoscopy and pathology reports from six local hospitals, we identified potentially eligible persons with CRN (cases) or controls who had no neoplasia on colonoscopy between January 1, 2000 and December 31, 2002. Consenting subjects completed a survey encompassing medical and family history, physical measures, lifestyle habits, and diet.

Surveys were completed by 20 (15%) of 130 potentially eligible cases and by 54 (13%) of 408 potentially eligible controls. The following factors differed between cases and controls: living with a spouse/significant other (55% vs. 80%; P=0.034); prior pelvic irradiation (20% vs. 2%; P=0.019); having a first-degree relative with CRC (25% vs. 7%; P=0.05); having had a prior sigmoidoscopy, colonoscopy, or barium enema (15% vs. 41%; P=0.038); and lightest weight since age 21 (155lbs vs. 135lbs; gender-adjusted P=0.049).

The low recruitment rate of this retrospective case-control study precludes its use for a larger, more definitive study. Several potential risk factors for advanced sporadic CRN were identified. It remains to be determined whether these factors represent an artifact of selection bias or true risk factors that may be used to stratify risk and target screening in persons under age 50.