A recent retrospective analysis of patients with above-average risk of colorectal cancer, found that multiple negative faecal immunohistochemical tests (FITs) were associated with a lower risk of advanced neoplasia, which ultimately, could slash the bottleneck of colonoscopies, say the researchers.
The findings suggest that multiple negative FITs could potentially identify individuals in high-risk surveillance who are not truly high risk, and free resources for truly high-risk individuals, reports Medscape.
The study, which was conducted in Australia by a team from Flinders University and published online in Clinical Gastroenterology and Hepatology, included patients who completed at least two FIT exams between surveillance colonoscopies and had no neoplasia or non-advanced adenoma at prior colonoscopy. Above-average risk was defined as a family history or by findings at surveillance colonoscopy.
The researchers analysed data from 4 021 surveillance intervals and 3 369 participants. A total of 1 436 had no neoplasia at the prior colonoscopy, 1 704 had non-advanced adenoma, and 880 had advanced adenoma.
Participants completed no or one to four FIT tests between colonoscopies, with the final colonoscopy performed within two years of FIT tests. The median age was 63.9 years; 53.6% were female; 71.1% had a prior adenoma; and 28.9% had a family history of colorectal cancer. A total of 29.4% of participants had one negative FIT; 6.9% had four negative FITs during the interval period; and 31.0% did not complete any FIT tests.
Of follow-up colonoscopies, 9.9% revealed advanced adenomas. Among the patients with no prior neoplasia, those with one negative FIT had a cumulative index function for advanced neoplasia at five years of 8.5% (95% confidence interval, 4.9%-13.3%). This was higher than for those with three negative FITs (4.5%; 95% CI, 2.0%-8.6%) or four negative FITs (1.9%; 95% CI, 0.5%-5.0%). The association held for individuals with prior non-advanced adenoma but not those with advanced adenoma.
Over the five-year interval, three or more negative FIT tests were associated with a 50%-70% reduction in advanced neoplasia risk at follow-up colonoscopy (P < .001). There was no significant association over a three-year interval.
The study has some limitations. It is a retrospective analysis between the years 2008 and 2019, and colonoscopy guidelines in the United States have since changed, with a recommendation of surveillance colonoscopy at 7-10 years after one-two adenomas discovered at surveillance colonoscopy, and the current study includes follow-up colonoscopy at five years.
“These data are informative for patients up to five years, but they’re not really informative afterwards. They just don’t have those data yet,” said Dr Reed Ness, associate professor of medicine at Vanderbilt University Medical Centre, Nashville, who was asked to comment on the study.
The authors also don’t describe what they mean by a family history of colorectal cancer risk, he added. “My take was that it’s an interesting result which would seem to support the possibility of returning some patients with a family history or adenoma history to a non-colonoscopy screening regimen after a negative surveillance colonoscopy. We’ll need to see where the data lead us in the future.
“We’re letting people go ten years now, and some people are uncomfortable with that. So you could think of a scenario where you use FIT to try to find people who might have higher-risk lesions that need to come back for colonoscopy within that decade,” he added.
That issue is particularly relevant, given the wide range of adenoma detection rates among gastroenterologists, because FIT could detect a polyp that was missed during a colonoscopy.
The study included two groups with increased risk – those with a family history of colon cancer, and those with previously detected adenomas. The family history cohort may be useful for clinical practice, according to Dr Priyanka Kanth, who was also asked to comment on the study.
“Some people may not need [a colonoscopy] at five years if they have no polyps found and negative FIT,” said Kanth, who is an associate professor of gastroenterology at Georgetown University, Washington.
She feels less certain about the group with previously detected adenomas, given the change in US guidelines. “We have already changed that, so I don’t think we need to really do FIT intervals for that cohort. I think this is a good study that has a lot of information and also reassures us that we don’t need such frequent colonoscopy surveillance.”
In October last year, MedicalBrief reported that results from a randomised clinical trial in Norway cast doubts on the commonly held belief that if everyone had a colonoscopy screening just once a decade, it could practically make colorectal cancer extinct.
In the landmark study, Michael Bretthauer, a gastroenterologist and researcher from the University of Oslo and Oslo University Hospital, who led the trial, said primary analysis found colonoscopy cut colon cancer risk only by roughly a fifth, far below past estimates of the test’s efficacy, and didn’t provide any significant reduction in colon cancer mortality.
“This is the first randomised trial showing outcomes of exposing people to colonoscopy screening versus no colonoscopy,” said Samir Gupta, a gastroenterologist at the University of California, San Diego and the VA who didn’t work on the trial, who added that it raised an uncomfortable question for doctors. “Maybe colonoscopy isn’t as good as we always thought it is.”
Colonoscopies are still a good test, he said, but it might be time to re-evaluate their standing as the gold standard of colon cancer screens. “This study provides clear data that it’s not as simple as saying ‘colonoscopy is the most sensitive test, and therefore it is the best’. It still prevented cancers.”
Previously, in early 2021, another article in MedicalBrief reported that FIT was as reliable as the traditional screening, according to health experts, and “more agreeable”.
“If your doctor tells you a colonoscopy is better, thatʼs not accurate,” Dr Alex Krist, chair of the US Preventive Services Task Force, an independent expert panel that reviews evidence and issues recommendations, had said. “The data show the tests are equally effective at saving lives.”
Study details
Multiple negative faecal immunochemical tests reduce risk of advanced neoplasia in a colonoscopy surveillance program
Molla Wassie, Graeme Young, Jean Winter, Charles Cock, Peter Bampton, Mahadya Rahman, Richard Heddle, Robert Fraser, Rosie Meng, Erin Symonds.
Published in Clinical Gastroenterology and Hepatology on 4 January 2022.
Abstract
Background & aims
In above-average risk individuals undergoing colonoscopy-based surveillance for colorectal cancer (CRC), screening with faecal immunochemical tests (FIT) between colonoscopies might facilitate personalisation of surveillance intervals. Since a negative FIT is associated with a reduced risk for CRC, we examined the relationship between number of rounds of negative FIT and risk for advanced neoplasia in individuals undergoing surveillance colonoscopy.
Methods
We conducted a retrospective cohort study on 4021 surveillance intervals in 3369 individuals (50-74y), who had completed a 2-sample FIT between colonoscopies, from one to four rounds at one-two yearly intervals, each with a negative result (<20μg haemoglobin/g faeces). Incidence of advanced neoplasia (CRC or advanced adenoma) was determined at the follow-up colonoscopy. Competing-risk regression was used to assess the association between multiple negative FIT results and the risk of advanced neoplasia within 2y.
Results
The incidence of advanced neoplasia in the cohort was 9.9% and decreased with increasing numbers of rounds of negative FIT results: 11.1% after one negative FIT to 5.7% after four negative FIT. The risk of advanced neoplasia was significantly lower in participants with three (Subdistribution Hazard Ratio (SHR), 0.50; 95% CI 0.24-0.97), and four (SHR, 0.33; 95% CI, 0.15-0.73) rounds of negative FIT compared with only one negative FIT.
Conclusions
There was a low risk of advanced neoplasia after multiple rounds of negative FIT in above average-risk people undergoing surveillance with no neoplasia or non-advanced adenoma at prior colonoscopy. This supports the use of interval FIT to personalise surveillance by lengthening colonoscopy intervals following multiple negative FIT results.
See more from MedicalBrief archives:
Colonoscopy may not be gold standard of colon cancer screening – large randomised trial
A FIT alternative to colonoscopy comes home in the US
Annual non-invasive test effective for colon cancer screening