Background: The question whether persons at familial or hereditary risk differ in terms of absolute, relative, or cumulative risk for colorectal cancer or not is of importance for the estimation of the potential of early detection of colorectal cancer in persons with familial or hereditary risks.
Methods: Based on the results of a systematic literature search on absolute, relative, and cumulative risks of familial and hereditary disposition for colorectal cancer as well as actual German tumour incidence data, projections were conducted.
Results: The absolute risk for colorectal cancer in familial risk persons identified by means of a questionnaire is increased by a factor of 2 - 4 depending on the age at questioning, the age of the family member at cancer diagnosis and number of family members with colorectal cancer. Their absolute colorectal cancer risk equals that of persons without this risk who are 10 to 15 years older. Persons with hereditary risk show an increase in risk by a factor of 8 - 80.
Conclusion: Persons aged 40 to 45 years with a familial risk constellation show a risk for colorectal cancer that equals the risk of 55- to 59-year-old persons from the general population. Therefore, the legal right for screening colonoscopy should be extended to the persons at risk aged 40 to 45 years. Persons suspected for hereditary risk should have a genetic counselling and, in case of germ mutation, a colonoscopic surveillance according to the actual guidelines.
Copyright Georg Thieme Verlag KG Stuttgart . New York.