Genetica van darmkanker. II. Erfelijke achtergrond van sporadische en familiaire darmkanker

- About 15 of patients with colorectal cancer have a positive family history: 5 have hereditary colorectal cancer (hereditary non-polyposis colorectal carcinoma (HNPCC), familial adenomatous polyposis (FAP) or some other hereditary syndrome), while in 10 no clear hereditary pattern can be recognized (‘familial colorectal cancer’).

- In sporadic and in familial intestinal cancer, a demonstrable hereditary predisposition may undoubtedly exist.

- HNPCC is often characterized by microsatellite instability, i.e. an increased number of short DNA sequences in the DNA indicating a disorder in DNA repair and a mutation in a DNA ‘mismatch repair’ (MMR) gene.

- Indicative of hereditary bowel cancer on the basis of such an MMR gene mutation are: (a) presence of bowel cancer in ≥ 3 relatives, (b) early age at the time of the diagnosis of ‘bowel cancer’, (c) multiple primary bowel tumours, (d) uterine cancer in the family and (e) bowel and uterine cancer in a woman.

- Recent data demand a new subdivision of hereditary bowel cancer, based upon both the clinical picture and the results of DNA-tests.

- The genetic alterations in colonic adenomas and carcinomas are known to a large extent. In future these insights may be important in clinical practice, such as a more individual determination of the patient's prognosis and accordingly, of the treatment and follow-up.