BACKGROUND: First-degree relatives of patients with colorectal cancer are at increased risk for colorectal cancer as well. Nevertheless, participation in the German national screening program stagnates at 2-3 percent per year even in this high-risk population.

AIM: The study is aimed to increase the portion of the first-degree relatives on 50% which take up a preventive colonoscopy.

METHODS: Cluster-randomized controlled multi-center trial. Study sites (clusters) are mainly certified cancer centers and office-based gastroenterologists from all over Germany. Index-patients with colorectal cancer of different stages are asked to hand over the study material to their relatives, consisting of an invitation to a nurse-led counseling on preventive colonoscopy and an one-to-one appointment with a clinical expert of one of the study sites next.

Inclusion Criteria:

• aged 18 and over
• being first-degree relatives of patients with diagnosed colorectal cancer
• able to understand German

Exclusion Criteria:

• Familial Adenomatous Polyposis
• utilization of diagnostic colonoscopy within the past 5 years
• being ever treated for colorectal cancer
• actual inflammatory bowl disease
• comorbidities associated with reduced further life expectancy (ECOG performance status >3