Colorectal cancer (CRC) remains the third most common type of cancer diagnosed in men and women in the United States. Experts project that over 28.000 men and over 23,000 women will die from CRC in 2022.
The dire impact and high mortality associated with CRC suggest it could greatly benefit from effective screening techniques. Current screening options include fecal occult blood testing, which evaluates the presence of blood in the feces, and endoscopic imaging by sigmoidoscopy, which looks at the lower part of the colon, or colonoscopy, which looks at the entire colon.
A colonoscopy allows doctors to examine the inside of the colon by inserting a colonoscope, an instrument with a light and camera, into the rectum. This procedure enables doctors to look for signs of diseases, including CRC.
Despite the popularity of colonoscopy screening to detect CRC, no studies have substantiated the long-term effect on CRC mortality. To address this question, a team of researchers initiated a multi-center, randomized trial enrolling healthy volunteers from Poland, Norway, Sweden, and the Netherlands over five years. The study, called The Northern-European Initiative on Colorectal Cancer (NordICC), provided follow-up data on over 80,000 participants.
Last week, the research team published their findings in the New England Journal of Medicine. The researchers randomly assigned about 1/3 of the participants (28,220) to the “invited group,” where they received invitations to have a colonoscopy. Of those invited for colonoscopy, 42% underwent the procedure. The researchers classified the remaining 2/3 of the participants (56,365) as the “usual-care group,” and they received no invitation or screening.
The study followed the participants for an average of 10 years. During the follow-up period, the researchers found 259 cases of CRC among the invited group and 622 cases in the usual-care group. The analysis showed those in the invited group had a slightly lower risk of CRC than those in the usual-care group (0.98% versus 1.20%). However, the analysis revealed that the risk of death from CRC remained similar between the invited and usual-care groups (0.28% versus 0.31%).
The researchers also estimated the number of patients needed to invite for screening to prevent one case of CRC. The statistical analysis revealed that for every 455 patients invited for colonoscopy, they could avoid one case of CRC. The adverse effects on those receiving a colonoscopy proved minimal, and no perforations or screening-related deaths occurred.
The study concludes that the risk of CRC is lower in participants invited to have a colonoscopy. While this study indicates that colonoscopy does not prevent CRC-related mortality, a major limitation of the current research may bias this finding. Less than half of the participants in the invited group actually underwent a colonoscopy. When looking at just the patients who received a colonoscopy (11,843), the analysis showed about a 30% decrease in CRC risk.
To reiterate that colonoscopy remains the gold standard to detect and prevent CRC, the American Society for Gastrointestinal Endoscopy released a statement in response to the publication of the study.