15-05-2025
Lower FIT Cutoffs Could Cut Costs of CRC Screening
Multitarget stool DNA tests — which are becoming more popular in the United States — have shown increased sensitivity over fecal immunochemical tests (FITs) for early colorectal cancer (CRC) screening, however FITs can be more cost-effective, according to the results of a new study.
'Although our study is not and does not claim to be a comprehensive cost-effectiveness analysis, our results indicate there would be much to gain if the current trends of decreasing FIT use rates and increasing [multitarget stool DNA test] use rates in the United States could be reversed,' wrote Hermann Brenner, MD, of Heidelberg University, Heidelberg, Germany, and colleagues.
The main argument in favor of multitarget stool DNA test 'has been their higher sensitivity compared with FIT. However, as previously shown, essentially the same sensitivity and specificity could be achieved at no incremental cost by lowering the FIT positivity threshold,' the authors pointed out.
In the study, recently published in the Annals of Internal Medicine , researchers compared screening test performance characteristics of a current multitarget stool DNA test (Cologuard, Exact Sciences) and a next-generation multitarget stool DNA test (Cologuard Plus, Exact Sciences) with a current FIT, using data from close to 170 patients.
The sensitivity for CRC was 73.8% for FIT vs 92.3% for the current multitarget stool DNA test, and 67.3% vs 93.9% for FIT vs the next generation multitarget stool DNA test. The sensitivity for any advanced neoplasia was 27.7% vs 46.4% for FIT vs the current multitarget test, and 25.2% vs 45.6% for FIT vs the next generation multitarget test.
However, specificities for no advanced neoplasia were higher for FIT at 94.9% and 94.8% compared with 86.6% for the current multitarget test and 90.6% for the next generation test.
The researchers assumed a 60% uptake of colonoscopy after a positive result. Overall, the screening costs for each case of advanced neoplasia or early detected CRC were 7-9 times higher for the multitarget stool DNA tests than FIT-based screening tests, they reported.
The costs per each additional early CRC case were more than $700,000 for both multitarget tests compared with FIT costs, they noted.
The findings are limited by the observational design, but the results suggest value in the increased use of FIT if the positivity threshold was reduced, the researchers stated.
'The FIT cutoffs used in different countries vary widely, and the current practice in the United States that hinders use of quantitative information from FITs and flexibility in defining the positivity threshold should be reconsidered,' they concluded.
Follow-up Is Essential to FIT Success
The invasiveness of CRC screening tests remains a significant impediment to screening, said David A. Johnson, MD, professor of medicine and chief of Gastroenterology at Eastern Virginia School of Medicine, Norfolk, Virginia, in an interview.
Stool-based testing can be done at home 'without the encumberments related to colonoscopy,' said Johnson, who was not involved in the study. However, stool-based testing, in particular FIT, is much less effective in detection of precancerous type polyps, and more of a colon cancer detection test.
The goal of screening is cancer prevention rather than simply detection, but these tests are better than no screening, he added.
The current study findings were not surprising, as the cost effectiveness of FIT in particular has been previously reported, albeit for the detection of CRC rather than precancerous polyps, Johnson told Medscape Medical News .
As for the effectiveness, 'disparities for sensitivity trade off with specificity,' he said. This would mean earlier detection of lesions, as opposed to over-testing for lesions that are not really there.
'FIT testing has been extremely effective when done in well-directed programmatic and systematic testing,' Johnson told Medscape Medical News . 'Following up on noncompliance as well as colonoscopy for positive tests is critical to optimize outcomes for this approach or run the risks for adverse outcomes,' he said.
The current study was limited by the potential impact of age and comorbidities on sensitivity testing, he noted. 'The assumptions for this present study would be subject to real world testing, which also might be subject to the demographic locations and insurance related factors for systematic testing and comprehensive follow-up.'
