The primary objective is to study the effect of communicating individual CRC risk score and screening recommendations on appropriate screening uptake at six months in individuals at low, moderate and high risk of developing CRC.

The secondary objectives:

• Assess the feasibility of a subsequent larger RCT designed to detect a change in clinical outcomes;
• Explore the impact of psychological factors (perceived susceptibility for CRC, perceived benefits from and barriers to screening) on appropriate screening uptake and participation rates.

The investigators will perform a pilot randomized controlled trial (RCT) of 880 residents from the canton Vaud (Switzerland) aged between 50 and 69 years. The QCancer calculator will be used to calculate the personalized risk score. The participants in the intervention group will receive a brochure with a personalized risk score and appropriate screening recommendations. The participants in the control group will receive the standard brochure of the Vaud CRC screening program, regardless of participants' risk level. Six months after the intervention, the investigators will measure the proportion of the participants who have undergone appropriate screening. Screening will be considered as appropriate if participants at high risk undertake colonoscopy and participants at low risk undertake FIT. Both tests are appropriate for participants at moderate-risk. The hypothesis is that in the intervention group, individuals will be more likely to undergo screening appropriate to a participant's individual risk level, whereas the choice of the screening test in the control group will not differ between risk levels.

This study should advance the field of risk-based screening. This may give insights about how to optimize CRC screening programs and offer to the population screening options with a better risk-benefit balance.

Colorectal cancer (CRC) can be effectively prevented by screening. Risk to develop CRC within 15 years is related to increasing age, sex, family history, and lifestyle and, thus, can vary from <1% to >15%.

Fecal immunochemical test (FIT) and colonoscopy are the most widely used screening tests. Colonoscopy is the most accurate test, but is related to risks of bleeding and perforation. Colonoscopy resources are limited, and high uptake of screening colonoscopy for low-risk individuals can cause long wait times for those with CRC symptoms or positive FIT. FIT is less costly can be done at home without preparation and, if done regularly, prevents most CRC mortality, especially in moderate and low-risk individuals. To offer the screening options with a reasonable risk-benefit balance, FIT should be recommended to individuals at low (<3% to develop CRC in 15 years) and moderate (3-6%) risk, and colonoscopy to those at high (>6%) risk.

The primary objective is to study the effect of communicating individual CRC risk score and screening recommendations on appropriate screening uptake at six months in individuals at low, moderate and high risk of developing CRC.

The secondary objectives:

• Assess the feasibility of a subsequent larger RCT designed to detect a change in clinical outcomes;
• Explore the impact of psychological factors (perceived susceptibility for CRC, perceived benefits from and barriers to screening) on appropriate screening uptake and participation rates.

The investigators will perform a pilot randomized controlled trial (RCT) of 880 residents from the canton Vaud (Switzerland) aged between 50 and 69 years. The QCancer calculator will be used to calculate the personalized risk score. The participants in the intervention group will receive a brochure with a personalized risk score and appropriate screening recommendations. The participants in the control group will receive the standard brochure of the Vaud CRC screening program, regardless of the participant's risk level. Six months after the intervention, the investigators will measure the proportion of the participants who have undergone appropriate screening. Screening will be considered as appropriate if participants at high risk undertake colonoscopy and participants at low risk undertake FIT. Both tests are appropriate for participants at moderate-risk. The hypothesis is that in the intervention group, individuals will be more likely to undergo screening appropriate to participant's individual risk level, whereas the choice of the screening test in the control group will not differ between risk levels.

This study should advance the field of risk-based screening. This may give insights about how to optimize CRC screening programs and offer to the population screening options with a better risk-benefit balance.

Inclusion Criteria:

• Aged between 50 and 69;
• Residents of the Canton of Vaud;
• Have signed an informed consent (paper or electronic).

Exclusion Criteria:

• Current CRC symptoms;
• Personal CRC history;
• In colonoscopy surveillance for follow-up of high-risk polyp(s);
• Inflammatory bowel disease;
• Having done a colonoscopy within 9 years or a FIT within 1,5 years;
• Planning to leave Switzerland definitively within the next six months.

Upon publication of the primary results, the data that support the findings of this study will be available from the corresponding author upon reasonable request.

Will become available upon publication of the primary results and remain available 5 years.

Reasonable request to the principal investigator