Evaluation and individualization of population-based colorectal cancer screening

Screening for colorectal cancer (CRC) has in RCTs been demonstrated to decrease disease-specific mortality by 16%, but there is a lack of evaluations of the effectiveness of the population-based screening programs implemented around the World.

The Swedish screening program in Stockholm-Gotland started in 2008 to invite birth cohorts 60-69-years to biennial stool test for occult blood (Hemoccult® test) with a follow-up colonoscopy after a positive test.

In 2015, the program changed to an immunological test (FIT) which quantitatively measures human blood, with different cut-off levels for a positive test in men and women (80 and 40 µg Hb/g feces, respectively).We aim to evaluate the effectiveness of the screening program regarding CRC mortality and incidence, to start-up biobanking of feces and mucosal biopsies from participants, to perform microbiome analyses of the biopsies to estimate association of bacterial organisms and lesions found, and to build a risk prediction model for CRC to be used in screening practice to indivudalize follow-up within the screening program or surveillance of adenomas.The screening program has a large population with evaluation based on over 1,300 CRC deaths.

Furthermore, a random successive inclusion was used to enable a non-invited control group for comparison.

The results of the microbiome analyses and risk modeling will provide evidence to reduce unnecessary screening follow-up while preserving the benefit of cancer risk reduction.