Background: The overall aim of the present work was to estimate the potential of early detection of colorectal cancer in persons with familial or hereditary risk. In this paper we present projections on how many persons in the age groups 30 - 49 and 30 - 54 years, respectively, would be classified as being at familial or hereditary risk when a questionnaire distributed by the "Netzwerk gegen Darmkrebs e. V." (network against colon cancer) is used for identification.
Methods: Based on the results of a systematic literature search on the validity of questionnaires, the estimated prevalence of familial and hereditary disposition for colorectal cancer as well as actual German tumour incidence data projections were calculated.
Results: Given a 10 % prevalence of persons with a familial risk in the German general population and a maximum knowledge of all tumour cases in kindred, a total of 5.7 % of all Germans in the age group 30 - 49 years would be classified as familial risk persons (7.2 % in the age group 30 - 54 years). Taking familial and hereditary risks into account 6.7 % (8.2 %) will have a positive questionnaire result.
Conclusion: If the questionnaire is used on a population-based level and the participation rate is 35 %, approximately 542 000 persons in the age group 30 - 49 years (816 000 in the age group 30 - 54 years) will be classified as having a familial or hereditary risk for colorectal cancer.