Harms of FIT screening outweigh benefits for those with no history of fecal hemoglobin
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Key takeaways:
- The number needed to screen to detect at least one advanced adenoma was higher among those with no detectable fecal hemoglobin in previously negative FITs.
- Similar results were reported for CRC detection.
Individuals with no detectable hemoglobin in previously negative fecal immunochemical tests had a “significantly higher” harm-to-benefit ratio for screening, with researchers suggesting less intensive screening for this population.
“We recently examined the predictive power of [fecal hemoglobin (f-HB)] levels and showed that f-Hb levels measured on two consecutive negative FITs could accurately predict the subsequent CRC risk,” Esther Toes-Zoutendijk, PhD, assistant professor in the department of public health at Erasmus University Medical Center, and colleagues wrote in Clinical Gastroenterology and Hepatology. “Given the association between f-Hb and CRC, the harm-to-benefit ratio may differ between individuals depending on their f-Hb concentrations measured in a previous negative FIT.”
They continued: “It is unknown what the benefit of CRC screening is for individuals with consecutive negative FITs with no detectable f-Hb, and how this benefit still compares to the harms of screening.”
Using data from the Dutch CRC screening program, Toes-Zoutendijk and colleagues sought to determine the harm-to-benefit ratio of FIT-based screening by previous f-Hb concentrations via the number needed to screening (NNS) and number needed to scope (NNSc) to detect at least one CRC or advanced adenoma. They included individuals aged 55 to 75 years who participated in up to four FIT screenings between January 2014 and December 2020.
According to results, 2,428,883 participants (mean age, 64.3 years; 52.9% women) completed at least two consecutive rounds of FIT; 1,308,684 (mean age, 68.2 years; 53% women) completed three rounds; and 150,958 (mean age, 71.1 years, 52.3% women) completed four rounds. In addition, 86.5%, 79.1% and 72.6% of participants in each round, respectively, had no f-Hb detected in previously negative FITs.
Of 85,252 participants with a positive FIT who underwent colonoscopy in the second round, 4,475 were diagnosed with CRC and 31,400 had advanced adenoma. Similarly, of 46,546 and 5,657 individuals with a positive FIT in the second and third rounds, 2,600 and 332 had CRC and 16,060 and 2,007 had advanced adenoma, respectively.
In the second round, the NNS to detect at least one advanced adenoma was 77.4 (95% CI, 76.5-78.2), which “remained relatively stable” for both the third (81.5; 95% CI, 80.3-82.8) and fourth (75.2; 95% CI, 72.1-78.6) screening rounds. Among individuals without a history of detectable f-Hb, the NNS to detect at least one advanced adenoma was “almost nine times” higher (OR = 8.71; 95% CI, 8.51-8.92), with similar results for CRC detection (OR = 7.38; 95% CI, 6.94-7.84).
Although less pronounced, the NNSc to detect at least one advanced adenoma remained higher among individuals without a history of detectable f-Hb (OR = 2.7; 95% CI, 2.7-2.8), as did the NNSc for CRC (OR = 1.7; 95% CI, 1.6-1.8).
“The harm-to-benefit ratio of screening is significantly higher for individuals with no history of detectable f-Hb in previous screening rounds compared to individuals with some detected f-Hb,” Toes-Zoutendijk and colleagues wrote. “These findings suggest that, although low-risk individuals benefit from CRC screening, a better balance between the harms and benefits may be achieved through less intensive screening in these low-risk individuals.”
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