Surveillance Options
No known cancer gene
In some families, gene testing will have been possible but will not have resulted in the discovery of a faulty gene. In other families, genetic testing may not have been possible. In both cases, the Genetics Department advises on the frequency of screening.
HNPCC
Colonoscopies every two years from the age of 25yrs. With surveillance there is a mortality reduction of 65%.
FAP
Lower GI screening from the age of 10yrs and upper GI screening from the age of 30yrs. Following prophylactic colectomy, annual sigmoidoscopies are carried out on the residual rectal area.
Genetic testing
Currently genetic testing is only available for the small number of individuals who may carry the HNPCC gene, the FAP gene or one of the rarer colorectal cancer syndromes, such as Peutz-Jeghers or MYH associated polyposis.
In order to test for one of these faulty genes, a relative affected by the condition needs to be available to provide blood for testing.
- If a faulty gene is identified in the relative, the test can be offered to other members of the family.
- If the same faulty gene mutation is found in the unaffected relative, they are at high risk of developing bowel cancer, or a related cancer.
- If the same faulty mutation is not identified in the unaffected relative, then their risk, and risk to offspring, will be that of the population.
- If no faulty gene is identified in the relative with bowel cancer, no further genetic testing can be done.
If Lynch syndrome is the suspected diagnosis, it may be possible to undertake some preliminary analysis on archival tumour tissue.
Risk reducing surgery
This is usually by way of colectomy in selected patients.
