▎ WuXi AppTec content team editor
Colorectal cancer is one of the major cancers that threaten human life and health, causing a serious social burden. According to the "2020 Global Cancer Statistics Report", the global colorectal incidence rate has jumped to the 3rd place after breast cancer and lung cancer, and the mortality rate has risen to 2nd. In China, the incidence of colorectal cancer jumped to 2nd place, ranking 5th among the leading causes of common cancer deaths.
Colorectal cancer screening and early diagnosis and treatment are effective measures to reduce colorectal cancer mortality in the population. A recent review published in NEJM Evidence-Based notes that to date, only the Guaiac Fecal Occult Blood Test (gFOBT) and sigmoidoscopy have been shown in randomized trials to reduce colorectal cancer incidence and associated mortality. However, the most commonly used screening methods are stool immunochemical testing (FIT) and colonoscopy. The Chinese Guidelines for Colorectal Cancer Screening and Early Diagnosis and Early Treatment regard colonoscopy as the gold standard for colorectal cancer screening. In addition, FIT has also replaced the traditional gFOBT as the main fecal occult blood detection technique because of its high sensitivity to the diagnosis of colorectal cancer.
To fill this gap, a team of researchers from Sweden conducted a randomized controlled trial called SCENESCO to evaluate the effectiveness of a one-time colonoscopy or two rounds of stool immunochemical testing (FIT) for colorectal cancer screening. It is also one of four large trials underway in the field, with preliminary findings recently published in The Lancet Gastroenterology & Hepatology. Different from the present
Preliminary results show similar detection rates and few adverse events for colorectal cancer between the two screening methods, and if longer-term data show a benefit for disease-specific mortality, only one colonoscopy and two rounds of fecal immunochemical testing can be applied to screening services for a wide range of people.
Screenshot source: The Lancet Gastroenterology & Hepatology
SCREESCO is a randomized controlled trial conducted in Sweden. The primary endpoints of the study were colorectal cancer incidence and mortality. Residents ≥ 60 years of age at the time of recruitment, subjects were assigned to three groups of only one colonoscopy, two rounds of fecal immunochemical testing (2 years apart) or control group (no intervention; standard diagnostic pathway), of which the ratio of colonoscopy to control group was 1:6, and the ratio of fecal immunochemical testing to control group was 1:2.
All individuals in the FIT screening group, with the exception of patients who need colonoscopy after adenoma resection or after diagnosis of colorectal cancer, provided the opportunity to repeat FIT screening after 2 years, regardless of whether they participated in the first round of FIT screening, regardless of whether the first round result was negative or positive.
The researchers reported initial participation rates, baseline results, and adverse events for subjects in both intervention groups from the completion of recruitment and screening until the completion of the second round of FIT screening.
The study showed that between 1 March 2014 and 31 December 2020, a total of 278,280 participants were included in the study. Among them, there were 31,140 cases in the colonoscopy group, 60,300 cases in the fecal immunochemical detection group (FIT group), and 186,840 cases in the control group.
Participants had high levels of adherence, similar detection rates, and low rates of adverse events
Of the 30,400 participants who received an invitation to colonoscopy, 10,679 (35.1%) were tested. Of the 60,137 participants who received FIT screening, 33,383 (55.5%) were tested.
In an intent screening analysis, the research team found:
Colorectal cancer was detected in 49 of the 31,140 cases in the colonoscopy group (0.16%), while colorectal cancer was detected in 121 out of 60,300 cases (0.20%) in the FIT group. There was no significant difference in the detection rate of colorectal cancer between the two screening modalities (relative risk [RR] 0.78, 95% CI 0.56–1.09).
Advanced adenomas were detected in 637 cases (2.05%) in the colonoscopy group and 968 (1.61%) in the FIT group, and colonoscopy had a 27% higher detection rate for precancerous lesions (RR: 1.27; 95% CI: 1.15–1.41).
Compared with the FIT group, the colonoscopy group found more non-advanced adenomamic disease (RR 2.82, 95% CI 2.63-3.02) and more right-sided lesions (i.e., non-advanced adenomas, advanced adenomas, and sessile serrated polyps).
In terms of safety, the incidence of adverse events was low, with 2 perforations and 15 cases of major bleeding in 16,555 cases of colonoscopy. There were no intervention-related fatalities.
Image credit: 123RF
In the intended screening population, analysis by sex stratification found that colonoscopy was more likely to detect advanced adenomas than FIT screening in both men and women (RR 1.27 for men, 1.12-1.45% for 95% CI; 1.27 for women, 95% CI 1.09-1.49 for women).
In addition, colonoscopy also detected more advanced sessile polyps on the right, and this difference was particularly pronounced in women (male RR/female RR=0.57, 95% CI 0.37-0.87; p=0.0090).
Preliminary findings suggest that the cancer findings in both groups were similar. However, the colonoscopy group made it easier to diagnose advanced adenomas than the FIT group.
Research highlights and future outlook
The paper notes that the new FIT screening method was used in this trial: it was only repeated once after 2 years. At present, most of the guidelines at home and abroad recommend that FIT screening be carried out once a year. The SCREESCO trial will provide new perspectives on the design of colorectal cancer screening protocols.
The study's randomized design, with control groups set up in populations that were not screened, without intervention, and a large sample size, made the study unique.
Screening engagement in the study means that the study will be able to answer the question of whether colonoscopy or FIT screening can reduce morbidity and mortality, which is important because a single screening can reduce the screening burden on individuals and healthcare settings. Moreover, the study covered a large number of certified endoscopists, as well as a diverse clinical site, which means that in the future, it is conditional to roll out routine screening practices in different regions to further reduce the occurrence of adverse events.
In addition, Sweden has a reliable national registration data system that can facilitate future follow-up visits. In the future, more detailed analysis and the accumulation of mortality data will promote the effectiveness of screening and more in-depth research.