FIT testing: an overview

Faecal immunochemical tests can improve colonoscopy triage in patients with iron deficiency: A systematic review and meta-analysis

BACKGROUND

Use of the faecal immunochemical test (FIT) to triage patients with iron deficiency (ID) for colonoscopy due to suspected colorectal cancer (CRC) may improve distribution of colonoscopic resources. We reviewed the diagnostic performance of FIT for detecting advanced colorectal neoplasia, including CRC and advanced pre-cancerous neoplasia (APCN), in patients with ID, with or without anaemia.

METHODS

We performed a systematic review of three databases for studies comprising of patients with ID, with or without anaemia, completing a quantitative FIT within six months prior to colonoscopy, where test performance was compared against the reference standard colonoscopy. Random effects meta-analyses determined the diagnostic performance of FIT for advanced colorectal neoplasia.

RESULTS

Nine studies were included on a total of n=1761 patients with ID, reporting FIT positivity thresholds between 4-150 µg haemoglobin/g faeces. Only one study included a non-anaemic ID (NAID) cohort. FIT detected CRC and APCN in ID patients with 90.7 % and 49.3 % sensitivity, and 81.0 % and 82.4 % specificity, respectively. FIT was 88.0 % sensitive and 83.4 % specific for CRC in patients with ID anaemia at a FIT positivity threshold of 10 µg haemoglobin/g faeces.

CONCLUSIONS

FIT shows high sensitivity for advanced colorectal neoplasia and may be used to triage those with ID anaemia where colonoscopic resources are limited, enabling those at higher risk of CRC to be prioritised for colonoscopy. There is a need for further research investigating the diagnostic performance of FIT in NAID patients.

Real-world data evaluating Guy's rapid diagnostic clinic as an alternate pathway for patients with FIT levels below 10

OBJECTIVE

To analyse the effectiveness of rapid diagnostic clinics (RDCs) as an alternative pathway for patients with concerning symptoms and a faecal immunochemical test (FIT) result <10. Our primary endpoint was rate of colorectal cancer (CRC) detection. Second endpoints were rates of other cancers and gastrointestinal (GI) serious benign conditions. Finally, we analysed the specific pathway followed by FIT <10 patients with cancer at Guy's and St Thomas NHS Foundation Trust (GSTT) RDC.

DESIGN

A retrospective and prospective cohort study.

SETTING

GSTT RDC, one of England's largest single-centre RDCs. Sociodemographic and clinical characteristics of FIT <10 patients were analysed descriptively.

PARTICIPANTS

Patients with an FIT result <10, seen at GSTT RDC between 1 January 2020 and 5 May 2023.

RESULTS

A total of 1299 patients with an FIT<10 were seen at GSTT RDC between January 2020 and May 2023. Of these, 66% (n=861) reported weight loss, 62% (n=805) pain, 37% (n=481) fatigue, 34% (n=444) were anaemic and 23% (n=301) had nausea and vomiting. Among these patients, 7% (n=88) received a cancer diagnosis, 36% (n=462) were identified as having a serious benign condition. Within the patients with cancer, 9% (n=8) were diagnosed with CRC. Among patients with serious benign conditions, 7% (n=31) were referred to colorectal, hepatopancreatobiliary, or upper GI specialists.

CONCLUSION

This study demonstrates the effectiveness of RDCs as an alternate pathway for FIT <10 patients with ongoing clinical concerns. These results contribute to enhancing patient care and optimising resource allocation within the healthcare system.

Screening for Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer death. Screening has been proven to reduce both cancer incidence and cancer-related mortality. Various screening tests are available, each with their own advantages and disadvantages and varying levels of evidence to support their use. Clinicians should offer CRC screening to average-risk persons aged 50 to 75 years; starting screening at age 45 years remains controversial. Screening may be beneficial in select persons aged 76 to 85 years, based on their overall health and screening history. Offering a choice of screening tests or sequentially offering an alternate test for those who do not complete screening can significantly increase participation.

Cost-Effectiveness of Liquid Biopsy for Colorectal Cancer Screening in Patients Who Are Unscreened

Importance

Despite recommendations for universal screening, adherence to colorectal cancer screening in the US is approximately 60%. Liquid biopsy tests are in development for cancer early detection, but it is unclear whether they are cost-effective for colorectal cancer screening.

Objective

To estimate the cost-effectiveness of liquid biopsy for colorectal cancer screening in the US.

Design, Setting, and Participants

In this economic evaluation, a Markov model was developed to compare no screening and 5 colorectal cancer screening strategies: colonoscopy, liquid biopsy, liquid biopsy following nonadherence to colonoscopy, stool DNA, and fecal immunochemical test. Adherence to first-line screening with colonoscopy, stool DNA, or fecal immunochemical test was assumed to be 60.6%, and adherence for liquid biopsy was assumed to be 100%. For colonoscopy, stool DNA, and fecal immunochemical test, patients who did not adhere to testing were not offered other screening. In colonoscopy-liquid biopsy hybrid, liquid biopsy was second-line screening for those who deferred colonoscopy. Scenario analyses were performed to include the possibility of polyp detection for liquid biopsy.

Exposures

No screening, colonoscopy, fecal immunochemical test, stool DNA, liquid biopsy, and colonoscopy-liquid biopsy hybrid screening.

Main Outcomes and Measures

Model outcomes included life expectancy, total cost, and incremental cost-effectiveness ratios. A strategy was considered cost-effective if it had an incremental cost-effectiveness ratio less than the US willingness-to-pay threshold of $100 000 per life-year gained.

Results

This study used a simulated cohort of patients aged 45 years with average risk of colorectal cancer. In the base case, colonoscopy was the preferred, or cost-effective, strategy with an incremental cost-effectiveness ratio of $28 071 per life-year gained. Colonoscopy-liquid biopsy hybrid had the greatest gain in life-years gained but had an incremental cost-effectiveness ratio of $377 538. Colonoscopy-liquid biopsy hybrid had a greater gain in life-years if liquid biopsy could detect polyps but remained too costly.

Conclusions and Relevance

In this economic evaluation of liquid biopsy for colorectal cancer screening, colonoscopy was a cost-effective strategy for colorectal cancer screening in the general population, and the inclusion of liquid biopsy as a first- or second-line screening strategy was not cost-effective at its current cost and screening performance. Liquid biopsy tests for colorectal cancer screening may become cost-effective if their cost is substantially lowered.

Performance of the fecal immunochemical test for colorectal cancer and advanced neoplasia in individuals under age 50

The increased demand for colonoscopy combined with increased incidence of colorectal cancer (CRC) among younger populations presents a need to determine FIT performance among individuals in this age group. We conducted a systematic review to assess test performance characteristics of FIT in detecting CRC and advanced neoplasia in younger age populations. A search through December 2022 identified published articles assessing the sensitivity and specificity of FIT for advanced neoplasia or CRC among populations under age 50. Following the search, 3 studies were included in the systematic review. Sensitivity to detect advanced neoplasia ranged from 0.19 to 0.36 and specificity between 0.94 and 0.97 and the overall sensitivity and specificity were 0.23 (0.17-0.30) and 0.96 (0.94-0.98), respectively. Two studies that assessed these metrics in multiple age categories found similar sensitivity and specificity across all age groups 30-49. Sensitivity and specificity to detect CRC was assessed in one study and found no significant differences by age groups. These results suggest that FIT performance may be lower for younger individuals compared to those typically screened for CRC. However, there were few studies available for analysis. Given increasing recommendations to expand screening in younger age groups, more research is needed to determine whether FIT is an adequate screening tool in this population.

Head-to-head comparison of the test performance of self-administered qualitative vs. laboratory-based quantitative fecal immunochemical tests in detecting colorectal neoplasm

Background:

Fecal immunochemical tests (FITs) are the most widely used non-invasive tests in colorectal cancer (CRC) screening. However, evidence about the direct comparison of the test performance of the self-administered qualitative a laboratory-based quantitative FITs in a CRC screening setting is sparse.

Methods:

Based on a CRC screening trial (TARGET-C), we included 3144 pre-colonoscopy fecal samples, including 24 CRCs, 230 advanced adenomas, 622 non-advanced adenomas, and 2268 participants without significant findings at colonoscopy. Three self-administered qualitative FITs (Pupu tube) with positivity thresholds of 8.0, 14.4, or 20.8 μg hemoglobin (Hb)/g preset by the manufacturer and one laboratory-based quantitative FIT (OC-Sensor) with a positivity threshold of 20 μg Hb/g recommended by the manufacturer were tested by trained staff in the central laboratory. The diagnostic performance of the FITs for detecting colorectal neoplasms was compared in the different scenarios using the preset and adjusted thresholds (for the quantitative FIT).

Results:

At the thresholds preset by the manufacturers, apart from the qualitative FIT-3, significantly higher sensitivities for detecting advanced adenoma were observed for the qualitative FIT-1 (33.9% [95% CI: 28.7–39.4%]) and qualitative FIT-2 (22.2% [95% CI: 17.7–27.2%]) compared to the quantitative FIT (11.7% [95% CI: 8.4–15.8%]), while at a cost of significantly lower specificities. However, such difference was not observed for detecting CRC. For scenarios of adjusting the positivity thresholds of the quantitative FIT to yield comparable specificity or comparable positivity rate to the three qualitative FITs accordingly, there were no significant differences in terms of sensitivity, specificity, positive/negative predictive values and positive/negative likelihood ratios for detecting CRC or advanced adenoma between the two types of FITs, which was further evidenced in ROC analysis.

Conclusions:

Although the self-administered qualitative and the laboratory-based quantitative FITs had varied test performance at the positivity thresholds preset by the manufacturer, such heterogeneity could be overcome by adjusting thresholds to yield comparable specificities or positivity rates. Future CRC screening programs should select appropriate types of FITs and define the thresholds based on the targeted specificities and manageable positivity rates.

Learning to be More Positive About FIT

Systematic application of the fecal immunochemical test (FIT) as a screen for colorectal cancer has been shown to meaningfully impact colorectal cancer incidence and mortality. However, there is room for improvement. FIT performance is impacted by a host of patient level factors such as sex and medication use. Meta-analysis has defined those factors most likely to result in a false positive or false negative test. Further work determining how best to gather information on important factors and incorporate them into the FIT result will further enhance the accuracy and outcomes accomplished with this valuable screening test.

Timeliness of Colonoscopy After Abnormal Fecal Test Results in a Safety Net Practice

Fecal testing can only reduce colorectal cancer mortality if patients with an abnormal test result receive a follow-up colonoscopy. As part of the Strategies and Opportunities to STOP Colon Cancer in Priority Populations (STOP CRC) project, we examined factors associated with adherence to follow-up colonoscopy among patients with abnormal fecal test results. As part of STOP CRC outreach, Virginia Garcia Memorial Health Center staff distributed 1753 fecal immunochemical tests (FIT), of which 677 (39 %) were completed, and 56 had an abnormal result (8 %). Project staff used logistic regression analyses to examine factors associated with colonoscopy referral and completion. Of the 56 patients with abnormal FIT results; 45 (80 %) had evidence of a referral for colonoscopy, 32 (57 %) had evidence of a completed colonoscopy within 18 months, and 14 (25 %) within 60 days of an abnormal fecal test result. In adjusted analysis, Hispanics had lower odds of completing follow-up colonoscopy within 60 days than non-Hispanic whites (adjusted OR 0.20; 95 % CI 0.04, 0.92). Colonoscopy within 60 days trended lower for women than for men (adjusted OR 0.25; 95 % CI 0.06-1.04). Among the 24 patients lacking medical record evidence of a colonoscopy, 19 (79 %) had a documented reason, including clinician did not pursue, patient refused, and colonoscopy not indicated. No reason was found for 21 %. Improvements are needed to increase rates of follow-up colonoscopy completion, especially among female and Hispanic patients.

Which Fecal Immunochemical Test Should I Choose?

OBJECTIVES

To summarize the fecal immunochemical tests (FITs) available in the United States, the 2014 pathology proficiency testing (PT) program FIT results, and the literature related to the test characteristics of FITs available in the United States to detect advanced adenomatous polyps (AAP) and/or colorectal cancer (CRC).

METHODS

Detailed review of the Food and Drug Administration's Clinical Laboratory Improvement Amendments (CLIA) database of fecal occult blood tests, the 2014 FIT PT program results, and the literature related to FIT accuracy.

RESULTS

A search of the CLIA database identified 65 FITs, with 26 FITs available for purchase in the United States. Thirteen of these FITs were evaluated on a regular basis by PT programs, with an overall sensitivity of 99.1% and specificity of 99.2% for samples spiked with hemoglobin. Automated FITs had better sensitivity and specificity than CLIA-waived FITs for detection of AAP and CRC in human studies using colonoscopy as the gold standard.

CONCLUSION

Although many FITs are available in the United States, few have been tested in proficiency testing programs. Even fewer have data in humans on sensitivity and specificity for AAP or CRC. Our review indicates that automated FITs have the best test characteristics for AAP and CRC.

Recommendations on Fecal Immunochemical Testing to Screen for Colorectal Neoplasia: A Consensus Statement by the US Multi-Society Task Force on Colorectal Cancer

The use of the fecal occult blood test (FOBT) for colorectal cancer (CRC) screening is supported by randomized trials demonstrating effectiveness in cancer prevention and widely recommended by guidelines for this purpose. The fecal immunochemical test (FIT), as a direct measure of human hemoglobin in stool has a number of advantages relative to conventional FOBT and is increasingly used relative to that test. This review summarizes current evidence for FIT in colorectal neoplasia detection and the comparative effectiveness of FIT relative to other commonly used CRC screening modalities. Based on evidence, guidance statements on FIT application were developed and quality metrics for program implementation proposed.

Recommendations on Fecal Immunochemical Testing to Screen for Colorectal Neoplasia: A Consensus Statement by the US Multi-Society Task Force on Colorectal Cancer

The use of the fecal occult blood test (FOBT) for colorectal cancer (CRC) screening is supported by randomized trials demonstrating effectiveness in cancer prevention and widely recommended by guidelines for this purpose. The fecal immunochemical test (FIT), as a direct measure of human hemoglobin in stool has a number of advantages relative to conventional FOBT and is increasingly used relative to that test. This review summarizes current evidence for FIT in colorectal neoplasia detection and the comparative effectiveness of FIT relative to other commonly used CRC screening modalities. Based on evidence, guidance statements on FIT application were developed and quality metrics for program implementation proposed.

Sensitivity and Specificity of Community Fecal Immunotesting Screening for Colorectal Carcinoma in a High-Risk Canadian Population

CONTEXT

Community-based programs are a common way of promoting colorectal cancer screening by primary care physicians. Fecal immunochemical testing (FIT) is a screening method commonly used in such programs. Fecal immunochemical testing has advantages to the patient as well as to clinical laboratories.

OBJECTIVE

To assess the operational test characteristics of a FIT pilot program in Calgary, Alberta, Canada, between April 2011 and May 2012.

DESIGN

Four hundred fifty-seven high-risk patients undergoing both FIT and colonoscopy were included. Areas under the curve and positive predictive values were derived for FIT values and biopsy-proven neoplasia. Subgroup analysis was also performed on men and women and for ages older and younger than the mean age of 62 years.

RESULTS

For colorectal carcinoma and colonic adenomas the areas under the curve were 0.79 (95% confidence interval 0.71-0.87) and 0.60 (95% confidence interval 0.54-0.65), respectively. The positive predictive value of a positive FIT result for any neoplasia was 53%. The overall performance of the test for all neoplasia was better for men and better for older individuals.

CONCLUSIONS

The performance of FIT in this clinical setting was very good for detecting carcinoma, but marginal for detection of colonic adenomas.

Developments in Screening Tests and Strategies for Colorectal Cancer

BACKGROUND

Worldwide, colorectal cancer (CRC) is the third most common cancer in men and second most common in women. It is the fourth most common cause of cancer mortality. In the United States, CRC is the third most common cause of cancer and second most common cause of cancer mortality. Incidence and mortality rates have steadily fallen, primarily due to widespread screening.

METHODS

We conducted keyword searches on PubMed in four categories of CRC screening: stool, endoscopic, radiologic, and serum, as well as news searches in Medscape and Google News.

RESULTS

Colonoscopy is the gold standard for CRC screening and the most common method in the United States. Technological improvements continue to be made, including the promising "third-eye retroscope." Fecal occult blood remains widely used, particularly outside the United States. The first at-home screen, a fecal DNA screen, has also recently been approved. Radiological methods are effective but seldom used due to cost and other factors. Serum tests are largely experimental, although at least one is moving closer to market.

CONCLUSIONS

Colonoscopy is likely to remain the most popular screening modality for the immediate future, although its shortcomings will continue to spur innovation in a variety of modalities.

Cost-effectiveness of patient navigation to increase adherence with screening colonoscopy among minority individuals

BACKGROUND

Colorectal cancer (CRC) screening is underused by minority populations, and patient navigation increases adherence with screening colonoscopy. In this study, the authors estimated the cost-effectiveness of navigation for screening colonoscopy from the perspective of a payer seeking to improve population health.

METHODS

A validated model of CRC screening was informed with inputs from navigation studies in New York City (population: 43% African American, 49% Hispanic, 4% white, 4% other; base-case screening: 40% without navigation, 65% with navigation; navigation costs: $29 per colonoscopy completer, $21 per noncompleter, $3 per non-navigated individual). Two analyses compared: 1) navigation versus no navigation for 1-time screening colonoscopy in unscreened individuals aged ≥ 50 years; and 2) programs of colonoscopy with versus without navigation versus fecal occult blood testing (FOBT) or fecal immunochemical testing (FIT) for individuals ages 50 to 80 years.

RESULTS

In the base case: 1) 1-time navigation gained quality-adjusted life-years (QALYs) and decreased costs; 2) longitudinal navigation cost $9800 per QALY gained versus no navigation, and, assuming comparable uptake rates, it cost $118,700 per QALY gained versus FOBT but was less effective and more costly than FIT. The results were most dependent on screening participation rates and navigation costs: 1) assuming a 5% increase in screening uptake with navigation, and a navigation cost of $150 per completer, 1-time navigation cost $26,400 per QALY gained; and 2) longitudinal navigation with 75% colonoscopy uptake cost <$25,000 per QALY gained versus FIT when FIT uptake was <50%. Probabilistic sensitivity analyses did not alter the conclusions.

CONCLUSIONS

Navigation for screening colonoscopy appears to be cost-effective, and 1-time navigation may be cost-saving. In emerging health care models that reward outcomes, payers should consider covering the costs of navigation for screening colonoscopy.