COLORECTAL CANCER INCIDENCE AND MORTALITY IN SUBJECTS WITH POSITIVE FAECAL IMMUNOCHEMICAL BLOOD TEST WHO DO NOT ATTEND SCREENING COLONOSCOPY

Aims In the colorectal cancer screening programmes of the Veneto region, compliance with colonoscopy among subjects with a positive faecal immunochemical test (FIT) is firmly less than 90%. We compared the incidence of colorectal cancer (CCR) and cause-specific mortality in subjects with a positive who complied or did not comply with colonoscopy.

Methods We selected all the positive FITs occurred from January 1st, 2003 to December 31st, 2017, distinguishing between compliers and non-compliers with colonoscopy. These two cohorts were linked with the archives of the Veneto Cancer Registry and the Regional Mortality Registry in order to identify CCR diagnoses and deaths due to CCR, from the date of the screening test until to December 31st, 2018. We

calculated the cumulative incidence and cumulative mortality at 15 years, using the Kaplan-Meier estimator, and compared the two cohorts using the Cox model, adjusting by gender and five-year age class.

Results At 15 years from the screening test, the cumulative incidence of CCR was 48.1 ‰ (95% CI 45.6-50.7) among colonoscopy compliers and 61.1 ‰ (95% CI 52.9-70.6) in non-compliers, while cumulative mortality for CCR was 9.3 ‰ (95% CI 7.1-12.1) among compliers and 22.1 ‰ (95% CI 17.6-27.8) in non-compliers. The risk of dying by CCR among non-compliers was 120% higher than among compliers (Hazard Ratio 2.20, 95% CI 1.84-2.63).

Conclusions The excess of risk of cause-specific death among non-participants requires that screening programs adopt effective solutions to increase compliance with colonoscopy among subjects with a positive faecal occult blood test.