Editors

KaiKlintrup

Screening and Prevention of Colorectal Cancer

Screening aims at reducing mortality from bowel cancer by early diagnosis of the disease.
Faecal occult blood testing is only intended for the systematic screening of asymptomatic persons.
Screening policies vary from country to country. Find out about the national policy in your country.
Removing adenomatous colorectal polyps from symptomless individuals reduces the incidence of and mortality from colorectal cancer. However, all adenomas do not turn malignant during a person's lifetime.
Follow-up endoscopies in persons belonging to risk groups for bowel cancer are performed according to local guidelines.

Patients with colorectal cancer
Patients with adenomas
Patients with dominantly inherited predisposition to colorectal cancer
- Hereditary non-polyposis colorectal cancer (Lynch syndrome, HNPCC)
- Familial adenomatous polyposis (FAP)
Patients with ulcerative colitis Ulcerative Colitis
Persons with diagnosed colorectal cancer in close relatives. Remember to ask about family history in all patients with colorectal cancer or colorectal adenomas.

Screening of asymptomatic individuals is indicated in cases with marked familial susceptibility to cancer.
- All the three randomized long-term screening trials carried out in general population (50-75-year-olds) using Hemoccult II guaiac testing showed a decrease in the incidence of and mortality from colorectal cancer in the screened group Screening for Colorectal Cancer Using the Faecal Occult Blood Test, Hemoccult.
- 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 (see below).
- If a person's 1-2 close relative(s) has/have had colorectal cancer, it is warranted to consider performing a screening colonoscopy at an age that is 5 years lower than the age of the youngest affected relative at the time of his/her diagnosis.
- 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. Find out about locally available relevant disease registers (e.g. on Lynch, HNPCC, FAP).

The frequency of follow-up depends on the findings in the previous screening, e.g. the number, size and dysplasia grade of the adenomas.The chosen policy also varies between hospitals.
If adenomas were detected but the examination was incomplete or a polyp was only partially removed, colonoscopy is repeated after 1-6 months.
Follow-up should even be considered for hyperplastic polyps if they are large (> 1 cm), there are several of them or they are located in the proximal colon.

A patient with a diagnosed colorectal carcinoma or adenoma 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.
At 2-3-year intervals: patients with
- HNPCC
- a large adenoma (> 1 cm) or a villous or tubulovillous adenoma
- several adenomas
At 5-year intervals: patients with colorectal cancer (after the postoperative follow-up period)
At 5-10-year intervals: patients with 1-2 tubular adenomas less than 1 cm in diameter
Long-term follow-up is carried out on patients above 75 years of age with consideration to the patient's other illnesses and his/her situation in general.

Follow-up policies vary between hospitals and between individual patients according to risk factors (e.g. cancers in relatives). In principle, colonoscopy is performed at about 2-3-year intervals among patients who have had ulcerative colitis for more than 8 years.
Precancerous dysplasia is sought from mucosal biopsies. Detecting dysplasia from the histological specimens requires experience. If dysplasia is detected and confirmed, prophylactic colectomy is performed.
The diagnosis of carcinoma associated with colitis is difficult. The tumour usually does not grow in an exophytic or circular manner, instead it can be a benign-looking stricture or a poorly demarcated plaque.

Both conditions are carcinoma syndromes that are inherited dominantly. Persons who have inherited the disease have a notably high risk of colorectal cancer, which is why a regular endoscopy follow-up every 1-3 years is recommended. The patients usually become affected at a yonger age than average, unless it is prevented by adenoma removal or prophylactic colectomy.
In some countries there are national registers of these syndromes, where all affected families are noted. Find out about locally available registers and local policies concerning screening of persons at risk in these families.