| Risk Stratification |
Definition and Characteristic |
Recommendation |
| High-risk population |
High high-risk individuals: hereditary syndromes such as familial polyposis and Lynch syndrome associated with specific inherited gene mutations; lifetime risk for CRC is 100% familial polyposis and 40% women and 80% men in Lynch Syndromes; account for 4% of all CRC |
Identified through HRFQ; taking a careful family history followed by genetic testing; colonoscopy begins as early as possible, at least before age 40 years |
| Medium high-risk individuals: one or more family members having CRC without one of the hereditary syndromes; lifetime risk for CRC is 10-12% if one first-degree relative having CRC; account for 15-20% of all CRC |
Identified through HRFQ; taking a careful family history; colonoscopy begins at an age at least 10 years younger than the age at which the index family member had CRC or age 40 whichever comes first |
| Low high-risk individuals: personal history of chronic ulcerative colitis or Crohn colitis or Crohn colitis; account for 1% of all CRC in USA. |
Identified through HRFQ and iFOBT annual approach as primary screening; followed by full colonoscopy if either HRFQ or iFOBT positive; routine screening initiated before the onset of symptoms at age 50 years |
| Asymptomatic, average-risk (not low risk) population |
Low high-risk individuals: aged 40 - 80 years having one or more of the following: 1. Positive iFOBT; 2. A personal history of cancers or intestinal polyps; 3. Two or more of the following: (a) chronic diarrhea; (b) chronic constipation; (c) phlegmatically blood feces; (d) history of appendicitis or appendectomy; (e) history of chronic cholecystitis or cholecystectomy; (f) history of psychiatric trauma (e.g. divorce, death of relatives); 4. high-risk lifestyles: smoking, heavy alcohol consumption, obesity, physical inactivity, and diet high in animal fat and low in vegetables, fruit and fibers; lifetime risk for CRC is 5-6% in the West and Japan and China; sporadic CRC in such patients accounts for 75% of all CRC in the west. |
Identified through HRFQ and the iFOBT every 1-2 years approach as primary screening; followed by full colonoscopy if either HRFQ or iFOBT positive; routine screening (iFOBT every 1-2 years, FS every 5 years or combination of iFOBT every 1-2 years and FS every 5 years, Colonoscopy every 10 years) initiated before the onset of symptoms at age 50 years |
Note: CRC, colorectal cancer; iFOBT, immunochemical fecal occult blood test; FS, flexible sigmoidoscopy; HRFQ, high risk factor questionnaire.