[Familial occurrence of colorectal cancer: prevention, aftercare and genetic counseling].

Introduction: Colorectal cancer (CRC) is the third most common type of cancer in Switzerland in terms of annual new cases and cancer deaths. Since most cantons have an organized screening program, more people are recorded with a positive family history of CRC. In the majority, the familial form of CRC is present, a hereditary form is much less common. Relatives of patients with CRC are a heterogeneous group whose CRC risk varies. A good assessment of disease risk can optimize the benefit-risk ratio for more intensive prevention. These recommendations («expert opinion statement») are intended to serve as a basis in clinical practice for planning preventative care, monitoring and human genetic counseling in the presence of a family history positive for CRC.