VANCOUVER, B.C.—In patients with positive results on fecal immunochemical testing, adenoma detection rates have been reported, but less is known about the detection of sessile serrated lesions in the FIT-screened population. Two recent studies of large databases are informative, finding detection rates of approximately 5% to 6%.
The researchers say their data can be helpful in setting quality benchmarks in FIT-based screening programs.
“It’s estimated that approximately 20% to 30% of all colorectal cancers arise from serrated lesions via a pathway that’s distinct from the traditional adenoma carcinoma sequence,” said investigator Natalie Wilson, MD, an internal medicine resident at the University of Minnesota, in Minneapolis. “While the ADR in FIT-positive individuals has been estimated to be about 45% in men and 35% in women, the prevalence of SSLs in these individuals is not well studied.”
Study of VA Database
In a study that received the Lawlor Resident Award at the 2023 annual meeting of the American College of Gastroenterology, Dr. Wilson and her co-investigators examined a nationwide Veterans Affairs database of 51,526 individuals who underwent colonoscopy within 12 months of a positive FIT test (abstract 49). They found at least one clinically significant SSL during colonoscopy in 6.1% of patients overall, including 5.3% of females and 6.5% of males, Dr. Wilson reported.
Patients most likely to have SSLs in the multivariate analysis were individuals aged 70 to 79 years, those with a body mass index above 25 kg/m2 and those with a history of smoking. Black race was associated with lower detection of SSLs in FIT-positive individuals.
“Our rate of 6.1% is relatively similar to that of previous studies, whose rates were anywhere from 1.8% to 11.4%,” said Dr. Wilson, who noted that those studies varied in their exact definitions of serrated polyps.
Limitations of the new study include its lack of information on lesion size and location, number of endoscopists, and proportion of dedicated GI pathologists. The study population was also limited to the veteran population, which is mostly male, she acknowledged.
Systemic Review And Meta-Analysis
In another study aimed at determining the SSL detection rate in average-risk individuals with positive FIT tests, Fouad Jaber, MD, an internal medicine resident at the University of Missouri–Kansas City, and his co-investigators conducted a systematic review and meta-analysis that won a Presidential Poster Award at ACG 2023 (abstract P0326).
The researchers identified six relevant studies involving 252,455 FIT-positive individuals undergoing colonoscopy. Two studies used a FIT positivity threshold of 20 mcg/g of feces, while the remaining studies used a threshold of 10 mcg/g.
They found 14,026 people with at least one SSL, yielding a pooled SSL detection rate of 5.56% and a detection rate of 4.91% by a random-effects model. The pooled detection rate was 3.49% for proximal SSLs, based on three studies, and 2.05% for distal SSLs, also based on three studies.
“The findings reveal a significant and variable prevalence of SSLs in this population, with rates differing based on polyp location.”
Quality Benchmarks For SSL Rates
Drs. Jaber and Wilson suggested that SSL detection rates can be used as a quality benchmark in FIT-based population screening programs. “With the uptick in the use of noninvasive colorectal cancer screening strategies,” Dr. Wilson said, data from studies such as these “can help determine quality benchmarks for SSL detection rates moving forward.”
Commenting on the studies for Gastroenterology & Endoscopy News, Klaus MÖnkemÜller, MD, PhD, a professor of medicine at Virginia Tech Carilion School of Medicine, in Roanoke, said, “Both of these studies are important for several reasons. They provide epidemiological data on SSLs in U.S. patients, and their findings add information on the colonic distribution of these SSLs. The detection rate for SSLs, thus, appears to be a clinically relevant quality measure of colonoscopy.”
—Caroline Helwick
Drs. Jaber, MÖnkemÜller and Wilson reported no relevant financial disclosures.
This article is from the December 2023 print issue.