Population-based screening for colorectal cancer using an immunochemical faecal occult blood test: A comparison of two invitation strategies

Background: To date, there is no screening programme for colorectal cancer (CRC) in Flanders, Belgium. However, The European Code Against Cancer (2003) recommends a population-based approach for CRC screening. This study aimed to obtain information about potential participation rates for a population-based screening programme for CRC in Flanders, and to compare two invitation strategies. Methods: In 2009, a trial programme for CRC screening was set up in three Flemish areas for all average-risk people aged 50–74 years, using an immunochemical faecal occult blood test (iFOBT) with a cut-off value set at 75 ng/ml of haemoglobin. The faecal sampling set was sent at random by post (mail group) or provided by the general practitioner (GP group). Results: In total, 19,542 people were invited to participate. Of these, 8229 provided a faecal sample, resulting in an overall participation rate of 42.1%. Participation by mail and through the GP was 52.3% (95% CI, 51.3–53.2) and 27.7% (95% CI, 26.7–28.6), respectively. The difference of 24.6% was statistically significant (95% CI, 23.3–25.9, p < 0.001). Before the reminder letter was sent and the other invitation strategy was offered, the overall participation rate was 26.5% (n = 5176); 36.4% (95% CI, 35.5–37.4) for the mail group and 16.6% (95% CI, 15.8–17.3) for the GP group. The odds of participating in CRC screening was almost three times higher for people invited by mail as opposed to people invited through a GP (OR = 2.96, 95% CI, 2.78–3.14, p < 0.001). Women were more likely to participate in CRC screening than men (OR = 1.22, 95% CI, 1.15–1.30, p < 0.001). In addition, we found that inhabitants from residential (OR = 1.98, 95% CI, 1.85–2.11) and rural (OR = 2.90, 95% CI, 2.66–3.16) areas were more likely to participate than those in urban areas. Of the 8229 people who submitted a faecal sample, 435 (5.3%) had a positive iFOBT, and of those, CRC was diagnosed in 18 (5.7%) individuals. Compliance for follow-up colonoscopy was 72.9%, and did not differ between the mail (72.4%, 95% CI, 67.5–77.3) and GP groups (74.3, 95% CI, 66.2–82.5). Conclusion: Inviting people for CRC screening by means of a direct-mail invitation, and including a faecal sampling set (iFOBT), results in much higher participation rates than inviting people through the GP.