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Fecal immunochemical tests may be suboptimal for preventing right-sided colon cancers
Screening for colorectal cancer with fecal immunochemical tests effectively detected advanced neoplasia in the distal colon and rectum, but had suboptimal performance in the proximal colon, according to findings published in Annals of Internal Medicine.
“Several studies have shown that screening for colon and rectal cancer with the fecal immunochemical test (FIT) reduces the number of deaths due to this disease,” Manuel Zorzi, MD, MSc, from Veneto Tumour Registry, Azienda Zero, Padova, Italy, told Healio Internal Medicine. “Previous studies also suggest that the sensitivity of the FIT is greater for colorectal cancer and its precursors (ie, advanced adenomas) when they are located in the distal colon and rectum than for those in the proximal colon.”
“However, previous studies followed people for short periods after only one or two FIT screenings, or they studied too few subjects to obtain certain data on the long-lasting performance of repeated FIT in the different colonic sites,” he added.
Zorzi and colleagues conducted a retrospective study of 123,347 adults from Italy aged 50 to 69 years who completed as many as six FIT screenings over 12 years of follow-up to determine the long-term detection rates for advanced adenoma and colorectal cancer based on site-specific anatomical location (proximal colon, distal colon, or rectum). There were a total of 441,647 FIT screenings across all participants.
The researchers found 1,704 cases of advanced adenomas in the proximal colon, 3,703 in the distal colon and 1,220 in the rectum, and 200 cases of colorectal cancer in the proximal colon, 324 in the distal colon and 209 in the rectum.
There was a decrease in the detection rate for proximal colon cancer only from the first to the second screening round (0.63 to 0.36 per 1,000 screenees). However, the rate declined steadily across all six rounds for distal colon cancer (from 1.65 in the first round to 0.17 in the sixth), as well as rectal (from 0.82 in the first round to 0.17 in the sixth). Similarly, detection rates for advanced adenoma in the proximal colon decreased from 5.32 in the first round to 4.22 in the sixth and the rates in the distal colon declined from 15.2 in the first round to 5.02 in the sixth.
There were 150 cases of interval cancer diagnosed. The proximal colon (25.2%; 95% CI, 19.9-31.5) demonstrated a higher proportional interval cancer rate than the distal colon (6%; 95% CI, 3.9-8.9) or rectum (9.9%; 95% CI, 6.9-13.7).
“The study found that repeated FITs achieve a profound reduction in the detection rate of advanced neoplasia in the distal colon and rectum, indirectly supporting its efficacy in preventing colorectal cancer incidence and mortality in these locations,” Zorzi said. “On the other hand, only a marginal reduction was achieved in the proximal colon, indicating a suboptimal performance in preventing the age-related shift of colorectal cancer.”
“Future studies may address potential integration with primary colonoscopy screening to achieve more effective long-term prevention of the right-side shifting of colorectal cancer,” he added.
In an accompanying editorial, Chyke A. Doubeni, MD, MPH, from the University of Pennsylvania, and Theodore R. Levin, MD, from Kaiser Permanente Medical Center, and colleagues noted that it is a public health priority to increase the uptake of colorectal cancer screening.
“To be effective, the screening test must be acceptable to patients so they will complete it, and if the result is positive, it must be followed by prompt diagnostic testing and treatment,” they wrote. “Because it can be performed at home without a face-to-face office visit, FIT has many advantages for screening delivery efforts, ranging from one-on-one encounters to large population-based programs.” – by Alaina Tedesco
Disclosures: Doubeni reports being a member of the USPSTF. Levin and Zorzi report no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.