The results of the study, which was designed to be truly population based and to mimick national colorectal cancer screening programs, provide an estimate of the effect of screening colonoscopy in the general population.
However, they add that"optimism related to the effects of screening on colorectal cancer–related death may be warranted in light of the 50% decrease observed in adjusted per-protocol analyses." Researchers recruited healthy men and women from registries in Poland, Norway, Sweden, and the Netherlands between 2009 and 2014. Most participants came from Poland , followed by Norway and Sweden . Data from the Netherlands could not be included owing to data protection law.
Referring to Bretthauer's point about attendance to screening, Dominitz and Robertson add that in the United States, colonoscopy is the predominant form of screening for colorectal cancer and that in countries where colonoscopy is less established, participation may be very different. Given the"modest effectiveness" of screening colonoscopy in the trial, they assert that"if the trial truly represents the real-world performance of population-based screening colonoscopy, it might be hard to justify the risk and expense of this form of screening when simpler, less-invasive strategies are available."