Colorectal cancer is the third most common type of cancer in the world and the second largest cause of cancer death. Based on this, colorectal cancer has always been one of the key goals of the population in the field of early cancer screening.

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Colorectal cancer is the third most common type of cancer in the world and the second largest cause of cancer death. Based on this, colorectal cancer has always been one of the key goals of the population in the field of early cancer screening. Currently, the most widely used methods in colorectal cancer screening include fecal occult blood test and endoscopic screening (sigmoidoscopy or colonoscopy ).

It should be pointed out that most colorectal cancers develop from benign polyps, which means they can be found and removed through endoscopy. In current research and clinical practice, colonoscopy is the gold standard for the widespread application of colorectal cancer screening. Currently, colorectal cancer screening guidelines/expert consensus is recommended for colonoscopy screening every 10 years by academic groups at home and abroad.

However, on October 9, 2022, the results of a large-scale, population-based randomized trial published by the New England Journal of Medicine (NEJM) pointed out that the role of colonoscopy screening in reducing the risk of colorectal cancer may be overestimated!

Screenshot Source: NEJM

The paper points out that there are currently many different methods for early screening for colorectal cancer, but which detection method is the best method for colorectal cancer screening is currently lacking high-quality evidence. The results of several randomized trials show that guaiacin fecal occult blood test screening can reduce the relative risk of colorectal cancer death in the population by about 15%. However, this screening method has little or little effect on the risk of colorectal cancer.

Many clinical experts believe that compared with fecal occult blood test , endoscopic screening may be more effective in preventing the occurrence of colorectal cancer. Compared with fecal occult blood tests, endoscopic screening may be more effective in preventing the occurrence of colorectal cancer. The results of a summary and analysis study (3 randomized clinical trials included) showed that after 10 to 12 years of follow-up, the incidence of colorectal cancer decreased by as much as 25%.

In addition, colonoscopy screening may be more effective than sigmoidoscopy, because the endoscopy doctor can fully view the entire colorectal condition under the colonoscopy visual lens. Therefore, sigmoidoscopy has been largely replaced by colonoscopy .

It should be pointed out that because colonoscopy screening lacks sufficient randomized trial evidence for benefits, it has not been widely carried out worldwide. Furthermore, population participation rates remain poor because colonoscopy is invasive and requires adequate intestinal preparation.

Image source: 123RF

NordICC trial is a large-scale, multi-center, randomized clinical trial aimed at evaluating the impact of population-based colonoscopy screening on the risk of colorectal cancer and the risk of colorectal cancer-related deaths after 10 years. The study included subjects (ages between 55 and 64 years old) from four different countries, namely Poland , Norway , Sweden , and Nunthern , and randomly assigned at a ratio of 1:2 to undergo a single-use colonoscopy screening (screening group) or not screening (regular group).

screening was conducted from June 8, 2009 to June 23, 2014. All lesions found during colonoscopy need to be removed if feasible; all tumor lesions require biopsy . The main endpoints of the study were the risk of colorectal cancer and the risk of colorectal cancer-related death after median follow-up of 10 to 15 years; the secondary endpoint was all-cause death.

This paper reported follow-up data of 84,585 subjects (28,220 and 56,365 subjects in the screening group and the conventional group, respectively), of which 50.1% were male; the median age of subjects at random was 59 years old. As of the current analysis, the median follow-up time of both subjects was 10.0 years.

analysis results show that the proportion of subjects screened in different countries (that is, those who were included in the screening group and actually received screening) varying from 33.0% to 60.7%. Overall, the proportion of men is higher than that of women and the proportion of elderly people is higher than that of young people.

62 subjects (0.5% of the screened subjects) were diagnosed with colorectal cancer at screening. In addition, 3634 subjects (30.7% of screened subjects) detected adenomas at screening and were removed. There were 15 subjects (0.13%) with polypectomy-related major bleeding (all bleeding cases were treated by endoscopy without further intervention). No subjects had perforation or screen-related deaths within 30 days after screening.

Overall, the risk of colorectal cancer in the screening group was 0.98% (259 cases), 1.20% (622 cases) in the conventional group, and the risk ratio (RR) of the subjects in the two groups was 0.82 (95% CI: 0.70-0.93). This shows that the number of newly confirmed cases of colorectal cancer in subjects who underwent colonoscopy screening was 18% reduced in .

analysis pointed out that there are 455 patients who need to use colonoscopy screening to prevent the occurrence of colorectal cancer within 10 years (95%CI: 270-1429). For subjects diagnosed with colorectal cancer and known disease stages: 0.38% and 0.44% of the subjects in the screening and routine group were diagnosed with early stage (stage A or B) colorectal cancer, respectively, and 0.40% and 0.50% of the subjects in the screening and routine group were diagnosed with advanced stage (stage C or D) colorectal cancer, respectively. After 10 years of follow-up of

, the risk of colorectal cancer-related death in the screening group was .28% (72 deaths), and .31% (157 deaths) in the conventional group (RR=0.90; 95%CI: 0.64-1.16). The paper pointed out that the mortality rate of colorectal cancer-related in both groups was low, which was related to the improvement of colorectal cancer treatment options in the past 10 years. In addition, did not experience a significant decrease in the mortality rate of compared with those not screened. In terms of all-cause death, during the 10-year follow-up period, 3036 subjects (11.03%) in the screening group died of any cause, while 6079 subjects (11.04%) in the conventional group died of any cause (RR=0.99; 95% CI: 0.96-1.04). The analysis results after correction of

showed that if all subjects randomly assigned to the screening group were actually screened, the risk of colorectal cancer will decrease from 1.22% to 0.84% ​​ in 10 years (RR=0.69; 95% CI: 0.55-0.83). In addition, the risk of death of colorectal cancer in subjects in the screening group was 0.15%, while that in the conventional group was 0.30% (RR=0.50; 95% CI: 0.27-0.77).

The authors of the paper emphasized that the current study is " the world's first randomized study to prevent colorectal cancer by using colonoscopy ", but unfortunately, based on the current analysis results, the preventive role of colonoscopy screening in the risk of colorectal cancer may not be significantly better than the fecal occult blood test. The analysis results suggest that colonoscopy may not be an effective weapon to prevent colorectal cancer.

In the future, researchers will continue to follow up these subjects to observe whether the screening effect will become more obvious over time.

Reference

[1] Michael Bretthauer et al, Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death, New England Journal of Medicine (2022). DOI: 10.1056/NEJMoa2208375

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