FIT Screening Found to Be Unsatisfactory in 10% of Submitted Tests

Colorectal cancer (CRC) screening using the fecal immunochemical test (FIT) stool sample was found to be unsatisfactory and could not be processed in more than 10% of the samples submitted, according to a study published in Cancer Epidemiology, Biomarkers & Prevention.

FIT has been used as an effective way to screen for CRC. The test includes collecting a stool specimen that looks for hidden blood. The test is recommended by the US Preventive Services Task Force for screening in adults aged 45 to 75 years. FIT can be cheaper and more accessible than a colonoscopy but there is little knowledge on the reasons and prevalence of unsatisfactory FIT. This study aimed to evaluate the prevalence of unsatisfactory FIT as well as how many of those with an unsatisfactory FIT complete follow-up testing.

Large and small intestine | Image credit: Tom - stock.adobe.com

The study¹ included patients aged 50 to 74 years who had an average risk of CRC. It focused on those who completed an index FIT between 2010 and 2019 in a large, safety-net health system that gives health care to patients who are uninsured, lower-income, and racial/ethnic minorities. A multivariable logistic regression model was used to find associations with an unsatisfactory FIT and any follow-up testing after the unsatisfactory FIT was submitted.

There were 56,980 patients who completed an index FIT and were included in this study. A total of 10.2% of samples from the FIT were unsatisfactory, with 51% having an inadequate specimen, 27% having incomplete labeling, 13% being an old specimen, and 8% having a broken or leaking container.

Patients who were male (OR, 1.10; 95% CI, 1.03-1.16), Black (OR, 1.46; 95% CI, 1.33-1.61), Spanish-speaking (OR, 1.12; 95% CI, 1.01-1.24), were on Medicaid (OR, 1.42; 95% CI, 1.28-1.58), and received their FIT by mail (OR, 2.66; 95% CI, 2.35-3.01) had a higher association with having an unsatisfactory FIT test compared with other groups.

Although unsatisfactory tests occurred with some frequency, only 41% of patients with an unsatisfactory test took another test within 15 months, with it taking a median of 4.4 months for those who did complete a subsequent test. Patients who were aged 50 to 54 years (OR, 1.16; 95% CI, 1.01-1.39) and who received FIT by mail (OR, 1.92; 95% CI, 1.49-2.09) had a higher likelihood of completing a test after an unsatisfactory initial test.

“The fact that, in most instances, unsatisfactory FIT was not followed by a timely subsequent test highlights the need for systems to have a better, more comprehensive approach to tagging and following up unsatisfactory FIT,” co-author Po-Hong Liu, MD, a gastroenterology fellow at UT Southwestern Medical Center, said in a news release.²

There were some limitations to this study. The results may have limited applicability to safety-net systems. The study relied on notes from the laboratory on why the test was unsatisfactory, which were often brief. It is also possible that patients received follow-up care outside of the Parkland Health system. The window for follow-up testing being more than a year could have led to the capturing of annual tests rather than follow-up tests.

The researchers concluded that screening programs could help alleviate the breakdowns in specimen collection in patients using FIT. The patient-related reasons for FIT specimens that cannot be used could be avoided through better education and accessibility in instruction for completing a FIT.

References

1. Liu PH, Nair RG, Skinner CS, et al. Unsatisfactory fecal immunochemical tests for colorectal cancer screening: prevalence, reasons, and subsequent testing.
   Cancer Epidemiol Biomarkers Prev. Published online November 15, 2023. doi:10.1158/1055-9965.EPI-23-0507
2. More than 10% of samples from a stool-based colorectal cancer test may be unsatisfactory. News Release. American Association for Cancer Research; November 15, 2023. Accessed November 21, 2023. https://www.aacr.org/about-the-aacr/newsroom/news-releases/more-than-10-of-samples-from-a-stool-based-colorectal-cancer-test-may-be-unsatisfactory/