Evaluating the effects of a risk-adapted screening program for familial colorectal cancer in individuals between 25 and 50 years of age: study protocol for the prospective population-based intervention study FARKOR

BACKGROUND Colorectal cancer (CRC) is the second most common malignant disease and the second most common cause of cancer death in Germany. Official CRC screening starts at age 50. As there is evidence that individuals with a family history of CRC have an increased risk of developing CRC before age 50, there are recommendations to start screening for this group earlier. This study aims to evaluate the clinical and economic effects of a risk-adapted screening program for CRC in individuals between 25 and 50 years of age with potentially increased familial CRC risk. METHODS FARKOR (Familiäres Risiko für das Kolorektale Karzinom) is a population-based prospective intervention study. All members of cooperating statutory health insurance companies between 25 and 50 years of age living in a model region in Germany (federal state of Bavaria, 3.5 million inhabitants in this age group) can participate in the program between October 2018 and March 2020. Recruitment takes place through physicians and through a public campaign. Additionally, insurances contact recently diagnosed CRC patients in order to encourage their relatives to participate in the program. Physicians assess a participant's familial history of CRC using a short questionnaire. All participants with a family history of CRC are invited to a shared decision making process to decide on further screening options consisting of either undergoing an immunological test for fecal occult blood or colonoscopy. Comprehensive data collection based on self-reported lifestyle information, medical documentation and health administrative databases accompanies the screening program. Longterm benefits, harms and the cost-effectiveness of the risk-adapted CRC screening program will be assessed by decision analytic modeling. DISCUSSION The data collected in this study will add important pieces of information that are still missing in the evaluation of the effects and the cost-effectiveness of a risk-adapted CRC screening strategy for individuals under 50 years of age. TRIAL REGISTRATION German Clinical Trials Register, DRKS-IDDRKS00015097