Genetic Screening and Personalized Prevention in Colorectal Cancer.

Cancer per se is a genetic disease, either originating in germline mutations in cancer genes or in somatic mutations only present in the cancer cells. Therefore, personalized risk prediction, prevention, and treatment for cancer can be based on the results of genetic testing either in the germline or in the tumor. Surveillance regimens need to be based on appropriate risk assessment, which includes germline monogenic genetic testing - where appropriate - and in the future polygenic risk - possibly - for the general population. Treatment regimens should also include germline testing at least for cases suspicious of hereditary tumor diseases, followed by the analysis of somatic mutations within the tumor cell genome, raising a possible target for personalized therapy. Appropriate risk assessment is the key for suitable and, most importantly, individualized surveillance strategies especially in hereditary tumor syndromes. This concerns not only the patient but also the family members at risk. An overview about the different fields and aspects of genetic testing in colorectal cancer and its impact on personalized prevention will be given below.