Prevalence of Unsatisfactory Samples From FIT Tests for Colorectal Cancer Screening

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A retrospective cohort study by Liu et al published in Cancer Epidemiology, Biomarkers & Prevention investigated the prevalence and reasons for an unsatisfactory fecal immunochemical test (FIT). Researchers found that over 10% of the tests used for routine colorectal cancer screening contained unsatisfactory samples that could not be processed, mostly due to patient-related reasons, including inadequate or old specimens, incomplete labeling, or a broken or leaking container. In addition, only 40.7% of individuals with unsatisfactory tests received follow-up FIT or colonoscopy screening within 15 months of the failed test.

According to the American Cancer Society, colorectal cancer is the third-leading cause of cancer-related deaths in both men and women in the United States—and the second most common cause of cancer deaths when numbers for men and women are combined. In 2023, it is expected that the cancer will cause more than 53,000 deaths. Although colorectal cancer screening can detect the disease at an early stage, potentially reducing mortality, only about 72% of eligible adults were up-to-date on colorectal cancer screening in 2021.

Study Methodology

The researchers examined the electronic health record data of 56,980 individuals aged 50 to 74 who underwent FIT screening between 2010 and 2019 within the Dallas-based Parkland Health system, which primarily provides care for uninsured, lower-income, and racial/ethnic minority individuals. The tests were performed at health-care offices or via a mail-order system, the latter of which automatically sent a repeat test to individuals with an initial unsatisfactory result.

The researchers used multivariable logistic regression models to identify factors associated with an unsatisfactory FIT test and subsequent testing within 15 months of an unsatisfactory FIT test.


The study found that 10.2% of the 56,980 individuals tested had an unsatisfactory FIT test. Reasons included inadequate specimen (51%), incomplete labeling (27%), old specimen (13%), and broken/leaking container (8%). Unsatisfactory FIT was associated with being male (odds ratio [OR] = 1.10, 95% confidence interval [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), on Medicaid (OR = 1.42, 95% CI = 1.28–1.58), and having received the FIT by mail (OR = 2.66, 95% CI = 2.35–3.01).

Among individuals with an unsatisfactory FIT, fewer than half (41%) completed a subsequent test within 15 months (median = 4.4 months). Adults aged 50 to 54 years (OR = 1.16, 95% CI = 1.01–1.39) and those who received a FIT by mail (OR = 1.92, 95% CI = 1.49–2.09) were more likely to complete a subsequent test. Overall, Black patients were 1.46 times more likely to submit an unsatisfactory test, and patients who primarily spoke Spanish were 1.2 times more likely to submit an unsatisfactory test.

“Screening programs should address these breakdowns, such as specimen collection and labeling, to improve real-world effectiveness,” concluded the study authors.

Improving Accurate Testing

Based on the results of this study and those from previous studies, the authors suggested several potential solutions to improve complete and accurate FIT screening sampling. They include:

  • Wordless or low-literacy instruction pamphlets to eliminate language and literacy barriers
  • Preaffixed patient labels or barcodes to minimize labeling errors
  • Automated systems for identifying and contacting patients with unsatisfactory tests.

Rasmi Nair, MBBS, PhD, of the O’Donnell School of Public Health of UT Southwestern Medical Center, is the corresponding author of this study.

Disclosure: Funding for this study was provided by the National Institutes of Health and the Cancer Prevention and Research Institute of Texas. For full disclosures of the study authors, visit

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