Table 7.

Cascade concept

Level	Average risk	High risk
1	Colonoscopy in 10 years interval, from 50 years of age	Special procedure, for individual groups
2	Colonoscopy once in a lifetime, at 50 years of age	Special procedure, for individual groups
3	Flexible sigmoidoscopy in 5 years interval, from 50 years of age; colonoscopy to follow if positive	Special procedure, for individual groups
4	Flexible sigmoidoscopy once in a lifetime, at 50 years of age; colonoscopy to follow if positive	Special procedure, for individual groups
5	Flexible sigmoidoscopy once in a lifetime, at 50 years of age; colonoscopy to follow only if advanced adenoma is detected	Same as individuals with average risk, if resources are not available for colonoscopy
6	FOBT in annual interval after 50 years of age; if positively tested, colonoscopy or double contrast barium enema	Same as individuals with average risk, if resources are not available for colonoscopy

Adapted from: World Gastroenterology Organization/International Digestive Cancer Alliance. Practice Guidelines: Colorectal cancer screening. Available from: URL: http://www.worldgastroenterology.org/colorectal-cancer-screening.html. Last accessed on August 4, 2009.