Study Details
The cross-sectional observational study included individuals aged 50-75 years who provided stool samples for the DNA test and two FITs. Test accuracy was calculated for all surveillance indications.
For the post-polypectomy indication only, which is the most common and associated with a relatively low CRC risk, the long-term impact of stool-based surveillance was evaluated with the Adenoma and Serrated Pathway to Colorectal Cancer model. Stool-based strategies were simulated to tune each test’s positivity threshold to obtain strategies that are at least as effective as colonoscopy surveillance.
A total of 3453 individuals had results for all stool tests and colonoscopy; among them, 2226 had previously undergone polypectomy, 1003 had a history of CRC, and 224 had a familial risk.
Areas under the receiver operating characteristic curve for advanced neoplasia were as follows:
- 0.72 (95% CI, 0.69-0.75) for the multitarget stool DNA test
- 0.61 (95% CI, 0.58-0.64) for the FIT OC-SENSOR
- 0.59 (95% CI, 0.56-0.61) for the FIT FOB-Gold
Stool-based surveillance was estimated to be at least as effective as colonoscopy surveillance and required 5.6 to 9.5 stool tests over a person’s lifetime. DNA-based surveillance was more costly than colonoscopy surveillance, whereas FIT-based surveillance saved costs.
“These findings provide a basis to embark on a prospective intervention study to assess the clinical utility of FIT as an alternative to colonoscopy surveillance in a post-polypectomy CRC surveillance population,” the authors wrote.
In the United States, Ladabaum said, it would likely be possible to find FIT-based strategies that closely approximate or match surveillance colonoscopy — “if we could deploy FIT with the required flexibility, for example, by adjusting the threshold and if the reference surveillance standard were somewhat relaxed compared with current guidelines.”
He worries, however, that if FIT for screening and FIT for surveillance were optimized at different hemoglobin detection thresholds, “there could be confusion and room for error in real-world clinical implementation.”
The authors called for research to increase understanding of the mechanisms underlying progression from adenomas to malignancy over time, which may yield better biomarkers to improve stool test accuracy.
This study was funded by the Alpe d’HuZes charity and the Dutch Cancer Society. Exact Sciences provided test equipment and performed multitarget stool DNA test analysis. Sentinel Diagnostics provided equipment and reagents.
Carvalho and Veerle M. H. Coupé, PhD, disclosed several patents pending and/or issued. Other coauthors disclosed multiple financial relationships with private companies, including Exact Sciences and Sentinel, for research support, travel, board membership, advisory or speaker fees, consulting, employment, stock ownership, or patents.
Ladabaum disclosed no competing interests relevant to his comments.
A version of this article appeared on Medscape.com.
