Introduction
Different screening options for average-risk and higher-risk men and women aged 50 and over are reviewed here. The options take account of the availability of colonoscopy, flexible sigmoidoscopy, fecal occult blood test (FOBT), and barium enema. When screening resources are severely limited, the most realistic option would be fecal occult blood testing every year or two for average-risk men and women, starting at the age of 50.
The type of slide test used depends on screening resources and the dietary habits of the population.
Lower test positivity with Hemoccult II will tax colonoscopy resources less than more sensitive slide tests such as Hemoccult SENSA. Immunochemical tests are optimal, in that they require only two rather than three days of testing and require no dietary restrictions, but they cost more, which is a consideration when financial resources are low.
The diagnostic work-up can be with either colonoscopy, if available, or barium enema if colonoscopy is not readily available. Thus, the decision to identify separately people who are at increased risk depends on the colonoscopy resources available. If these are very limited, then people who are at increased risk can be screened along with average-risk people.
Screening Cascade
The colorectal cancer (CRC) screening cascade consists of a set of recommendations. The recommendations apply to different resource levels, beginning with 1 (highest resources) and ending with 6 (minimal resources available).
Cascade Level 1
The recommendations below are appropriate for countries with a relatively high level of resources (financial, professional, facilities) where the colorectal cancer incidence and mortality is high (International Agency for Research on Cancer [IARC] data) and is an important concern relative to other public health priorities.
Recommendations for Screening People at Average Risk
Colonoscopy for average-risk men and women, starting at the age of 50 and every 10 years in the absence of factors that would place them at increased risk
Recommendations for Screening People at Increased Risk
- People with a family history of colorectal cancer or adenomatous polyps.
- People with a first-degree relative (parent, sibling, or child) with colon cancer or adenomatous polyps diagnosed under the age of 60, or with two first-degree relatives diagnosed with colorectal cancer at any age, should be advised to have screening colonoscopy starting at the age of 40, or 10 years younger than the earliest diagnosis in their family, whichever comes first, and repeated every 5 years.
- People with a first-degree relative with a colon cancer or adenomatous polyp diagnosed when he or she was over the age of 60, or with two second-degree relatives with colorectal cancer, should be advised to be screened as average-risk persons, but starting at the age of 40.
- People with one second-degree relative (grandparent, aunt, or uncle) or third-degree relative (great-grandparent or cousin) with colorectal cancer should be advised to be screened as average-risk persons.
- Familial adenomatous polyposis (FAP). People who have a genetic diagnosis of FAP, or who are at risk of having FAP but in whom genetic testing has not been performed or is not feasible, should have an annual sigmoidoscopy, beginning at age 10 to 12, to determine whether they are expressing the genetic abnormality. Genetic testing should be considered in patients with FAP who have relatives at risk. Genetic counseling should guide genetic testing and consideration of colostomy.
- Hereditary nonpolyposis colorectal cancer (HNPCC). People with a genetic or clinical diagnosis of HNPCC, or who are at increased risk for HNPCC, should have colonoscopy every 1 to 2 years, starting at the age of 20 to 25 or 10 years earlier than the youngest age of colon cancer diagnosis in the family, whichever comes first. Genetic testing for HNPCC should be offered to first-degree relatives of persons with a known inherited mismatch repair (MMR) gene mutation. It should also be offered when the family mutation is not already known, but one of the first three of the modified Bethesda criteria is met.
- People with a history of inflammatory bowel disease or a history of adenomatous polyps or colorectal cancer are candidates for follow-up surveillance, rather than screening. Guidelines have been published for the surveillance of these individuals.
Cascade Level 2
The recommendations are the same as for level 1, but they apply when colonoscopy resources are more limited.
Recommendations for Screening People at Average Risk
Colonoscopy for average-risk men and women at age 50 once in a lifetime, in the absence of factors that would place them at increased risk.
Recommendations for Screening People at Increased Risk
Recommendations for screening people who are at increased risk are the same as for cascade 1.
Cascade Level 3
The recommendations are the same as for level 1, but they apply when the colonoscopy resources are more limited and flexible sigmoidoscopy resources are available.
Recommendations for Screening People at Average Risk
Flexible sigmoidoscopy for average-risk men and women, starting at the age of 50, every 5 years, in the absence of factors that would place them at increased risk. Diagnostic work-up with colonoscopy for positive sigmoidoscopy.
Recommendations for Screening People at Increased Risk
Recommendations for screening people at increased risk are the same as for level 1.
Cascade Level 4
The recommendations are the same as for level 3, but they apply when the flexible sigmoidoscopy and colonoscopy resources are more limited.
Recommendations for Screening People at Average Risk
Flexible sigmoidoscopy for average-risk men and women once in a lifetime at the age of 50, in the absence of factors that would place them at increased risk. Diagnostic colonoscopy work-up for positive sigmoidoscopy or advanced neoplasia, depending on the available colonoscopy resources.
Recommendations for Screening People at Increased Risk
Recommendations for screening people at increased risk are the same as for level 1.
Cascade Level 5
The recommendations are the same as for resource level 4, but they apply when diagnostic colonoscopy is severely limited.
Recommendations for Screening People at Average Risk
Flexible sigmoidoscopy for average-risk men and women once in a lifetime at the age of 50. Diagnostic colonoscopy only if advanced neoplasia is detected.
Recommendations for Screening People at Increased Risk
The recommendations for screening people at increased risk depend on the colonoscopic resources available.
Cascade Level 6
The recommendations are the same as for level 1, but they apply when colonoscopy and flexible sigmoidoscopy resources are severely limited.
Recommendations for Screening People at Average Risk
Fecal blood testing every year for average-risk men and women starting at the age of 50, in the absence of factors that would place them at increased risk. The type of test used depends on colonoscopy resources and the dietary habits of the population. Diagnostic work-up can be either with colonoscopy, if available, or barium enema if colonoscopy is not readily available.
Recommendations for Screening People at Increased Risk
The decision to separately identify these people for special screening (see level 1) depends on the available colonoscopy resources. If not available, these people can be screened along with average-risk individuals.
New Tests
Computed tomographic colonoscopy (CTC) and fecal DNA testing are available only in a few high-resource countries and are generally not applicable globally. However, where available, they can be offered to average-risk men and women, starting at the age of 50, who do not wish to be screened by other more standard methods, in order to increase the low number of people currently being screened in these countries.
