Prevention and screening of colorectal cancer.

Code

Quality of Evidence

Definition

High

Further research is very unlikely to change our confidence in the estimate of effect.

Several high-quality studies with consistent results
In special cases: one large, high-quality multi-centre trial

Moderate

Further research is likely to have an important impact on confidence in the estimate of effect and may change the estimate.

One high-quality study
Several studies with some limitations

Low

Further research is very likely to have an important impact on confidence in the estimate of effect and is likely to change the estimate.

One or more studies with severe limitations

Very Low

Any estimate of effect is very uncertain.

Expert opinion
No direct research evidence
One or more studies with very severe limitations

The levels of evidence [A-D] supporting the recommendations are defined at the end of the "Major Recommendations" field.

In General

Prevention of colorectal cancer by screening will probably prove cost-effective. This is based on the facts that colorectal cancer is common (among the three most common cancers in the industrialized world), there is an operable benign precursor lesion (adenoma) and methods suitable for screening of colorectal tumours are available. Research is ongoing on the applicability of different methods both to population-based screening and to screening of risk groups.

Detection and Removal of Adenomata

Removing adenomatous colorectal polyps from symptomless persons reduces the incidence of and mortality from colorectal cancer. However, all adenomata do not turn malignant during a person's lifetime.
If a polyp is detected the whole colon should be examined and all polyps removed. Polyp removal may be considered unnecessary if the patient is of high age (>75 years) and the polyp can be deemed benign on the basis of its small size (<5 mm in diameter).

Follow-up of Patients with Colorectal Adenomata

A patient with a diagnosed colorectal adenoma or carcinoma has an increased risk of developing a new colorectal neoplasm. Follow-up is worthwhile in patients in whom the possible new colorectal neoplasm is considered to pose a greater health risk than other diseases during the next 10 years.
For recommendations for follow-up of patients with adenomata, see the Finnish Medical Society Duodecim guideline "Long-term Follow-up of Patients at Risk of Colorectal Cancer".

Asymptomatic Persons

Screening of asymptomatic persons is indicated in cases with marked familial susceptibility to cancer.
- If a person belongs to a family with dominant inheritance of colorectal cancer, appropriate investigations of the family members should be arranged because it may be possible to detect the genetic predisposition by gene testing and thus verify the need of screening tests.
- If a person's two close relatives have had colorectal neoplasm, testing of faecal blood is recommended at 1- to 2-year intervals starting at an age that is 5 years lower than the age of the youngest affected relative at the time of his/her diagnosis.
- If one close relative of a person has developed colorectal cancer before the age of 55, the person is considered to belong to the same risk group as general population.
- All the three randomized long-term screening trials carried out in general population (50- to 75-year-olds) using Hemoccult II guaiac testing showed a decrease in the incidence of and morbidity from colorectal cancer in the screened group (Hewitson et al., 2007) [A].
- The cost of colorectal cancer screening per life-year gained is lower than with cervical cancer screening and in the same range with breast cancer screening.
- Population-based screening based on faecal occult blood testing (FOBT) requires, however, an increase in colonoscopy capacity.
- In some countries, yearly FOBT and sigmoidoscopy every 5 years is recommended for 50- to 75-year-olds, but true general screening covering the whole population has not been arranged.
- The effect of fiberoptic sigmoidoscopy combined with removal of adenomata, performed once at the age of 50 to 60 years, on the incidence of colorectal cancer is under research as an optional strategy.

Examining a Symptomatic Patient

The most common symptom of a malignant colorectal tumour is the development of anaemia. Significant haemorrhagic anaemia always warrants the examination of the whole large intestine (colonoscopy).
Other symptoms suggesting colorectal cancer include pain, macroscopic blood in the stools, and a palpable abdominal mass. However, the majority of patients with colorectal cancer are symptomless.
There is a view that the colon of a patient with intestinal symptoms should be examined at least once (colonoscopy or colography with sigmoidoscopy). According to another view, the primary investigation of intestinal symptoms (pain, functional disturbances of the bowel, macroscopic blood in the stools) is sigmoidoscopy. If the symptoms are not explained by this, the next step would be testing of occult faecal blood if the only goal is to exclude a symptomatic neoplasm of the proximal bowel.

Related Resources

Refer to the original guideline document for related evidence, including Cochrane reviews and other evidence summaries.

Definitions:

Classification of the Quality of Evidence

Code	Quality of Evidence	Definition
A	High	Further research is very unlikely to change our confidence in the estimate of effect. Several high-quality studies with consistent results In special cases: one large, high-quality multi-centre trial
B	Moderate	Further research is likely to have an important impact on confidence in the estimate of effect and may change the estimate. One high-quality study Several studies with some limitations
C	Low	Further research is very likely to have an important impact on confidence in the estimate of effect and is likely to change the estimate. One or more studies with severe limitations
D	Very Low	Any estimate of effect is very uncertain. Expert opinion No direct research evidence One or more studies with very severe limitations

GRADE (Grading of Recommendations Assessment, Development and Evaluation) Working Group 2007 (modified by the EBM Guidelines Editorial Team).

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