Lifetime Risk for Colorectal Carcinoma According to Houlston et al

Houston et al reported the lifetime risk for colorectal carcinoma in a person based on family history using the data of Lovett.

History	Lifetime Risk
autosomal dominant pedigree	1 in 2 (50%)
2 first degree relatives affected	1 in 6 (17%)
1 first degree relative affected with onset < 45 years of age	1 in 10 (10%)
1 first degree relative and 1 second degree relative affected	1 in 12 (8%)
1 first degree relative affected, any age	1 in 17 (6%)
population at large	1 in 50 (2%)

after Table I, page 367 (Houlston, 1990)

The screening policy used in their clinic depended on the lifetime risk:

(1) For persons with a lifetime risk < 10%: fecal occult blood test

(2) For a person with a lifetime risk >= 10% with no polyps: colonoscopy every 5 years

(3) For a person with a lifetime risk >= 10% with polyps: colonoscopy every 3 years

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