March's paper of the month looks at the comparison between immunochemical testing for fecal blood (FIT) and Flexible Sigmoidoscopy (FS) as tools for colorectal cancer screening in a Norwegian population.
Kristin R Randel, Anna L Schult, Edoardo Botteri, Geir Hoff, Michael Bretthauer, Giske Ursin, Erik Natvig, Paula Berstad, Anita Jørgensen, Per Kristian Sandvei, Marie Ek Olsen, Svein Oskar Frigstad, Ole Darre-Næss, Espen R Norvard, Nils Bolstad, Hartwig Kørner, Arne Wibe, Knut-Arne Wensaas, Thomas de Lange, Øyvind Holme.
Gastroenterology 2021;160:1085–1096.
What is known about the subject?
Screening with sigmoidoscopy or guaiac based fecal occult blood tests reduce colorectal cancer mortality in randomized controlled trials. The comparative effectiveness of sigmoidoscopy vs immunochemical testing for fecal blood (FIT) is unknown. It is very important to have data on this effect when designing and implementing a colorectal cancer screening program.
What the study adds?
The south-east Norwegian population was called for colorectal cancer screening and was randomized to flexible sigmoidoscopy only once vs FIT testing once every second year between 2012 and 2019. Of 154,743 individuals randomized, 15,452 (10%) were excluded before the first invitation, leaving 139,291 individuals for the intention-to-treat analysis. Of these, 69,195 were invited to sigmoidoscopy and 70,096 to FIT. The participation rate was 52% for sigmoidoscopy, 58% in the first FIT round, and 68% for 3 cumulative FIT rounds. Baseline results from this randomized effectiveness trial show that more colorectal cancers (0.49% vs 0.27%; OR, 1.87; 95% CI, 1.54–2.27) and advanced adenomas (2.7% vs 2.4%; OR, 1.14; 95% CI, 1.05–1.23) were detected after three cumulative rounds of FIT compared to sigmoidoscopy screening. The risk of perforation and significant bleeding was comparable between the two screening modalities (FS: 0.05% vs FIT: 0.07%, p=0.13).
Implications for colorectal practice
Experience gained so far provides valuable information for health policy decision makers in implementing and improving organized CRC screening programs. FIT seems to be more effective than sigmoidoscopy not only in the actual screening outcomes but also in the participation rates which are probably the most important element of a successful screening program.
