Evaluation of fecal immunochemical tests for colorectal cancer screening

Comparative effectiveness of five fecal immunochemical tests using colonoscopy as the gold standard: study protocol

BACKGROUND

There are nearly 50,000 colorectal cancer (CRC) deaths in the United States each year. CRC is curable if detected in its early stages. Fecal immunochemical tests (FITs) can detect precursor lesions and many can be analyzed at the point-of-care (POC) in physician offices. However, there are few data to guide test selection. Broader use of FITs could make CRC screening more accessible, especially in resource-poor settings.

METHODS

A total of 3600 racially and ethnically diverse individuals aged 50 to 85 years having either a screening or surveillance colonoscopy will be recruited. Each participant will complete five FITs on a single stool sample. Test characteristics for each FIT for advanced colorectal neoplasia (ACN) will be calculated using colonoscopy as the gold standard.

RESULTS

We have complete data from a total of 2990 individuals. Thirty percent are Latino and 5.3% are black/African American. We will present full results once the study is completed.

CONCLUSIONS

Our focus in this study is how well FITs detect ACN, using colonoscopy as the gold standard. Four of the five FITs being used are POC tests. Although FITs have been shown to have acceptable performance, there is little data to guide which ones have the best test characteristics and colonoscopy is the main CRC screening test used in the United States. Use of FITs will allow broader segments of the population to access CRC screening because these tests require no preparation, are inexpensive, and can be collected in the privacy of one's home. Increasing CRC screening uptake will reduce the burden of advanced adenomas and colorectal cancer.

Fecal Immunochemical Test: The World's Colorectal Cancer Screening Test

The fecal immunochemical test (FIT) is a tool used for colorectal cancer screening and its use is growing rapidly. FIT, applied as a qualitative or quantitative test, has far better sensitivity for hemoglobin than older, guaiac fecal occult blood tests. This translates into several advantages of FIT, including ability to screen using only 1 stool sample per cycle. This article reviews current understanding of FIT performance as a 1-time test and when applied programmatically. It outlines how to apply the test at the patient level and track performance at the program level. Future prospects for FIT application are highlighted.

Optimizing the Quality of Colorectal Cancer Screening Worldwide

Screening, followed by colonoscopic polypectomy (or surgery for malignant lesions), prevents incident colorectal cancer and mortality. However, there are variations in effective application of nearly every aspect of the screening process. Screening is a multistep process, and failure in any single step could result in unnecessary morbidity and mortality. Awareness of variations in operator- and system-dependent performance has led to detailed, comprehensive recommendations in the United States and Europe on how colonoscopy screening should be performed and measured. Likewise, guidance has been provided on quality assurance for nonprimary colonoscopy-based screening programs, including strategies to maximize adherence. Quality improvement is now a validated science, and there is clear evidence that higher quality prevents incident cancer and cancer death. Quality must be addressed at the levels of the system, provider, and individuals, to maximize the benefits of screening for any population. We review the important aspects of measuring and improving the quality of colorectal cancer screening.

An early report of a screening program for colorectal cancer in Guangzhou, China

Background

We launched a screening program for colorectal cancer (CRC) in Yuexiu District, Guangzhou, China, in 2014. Here we aimed to report the early results of the program and evaluate the benefits of a screening questionnaire.

Methods

Residents aged between 50 and 74 were eligible for the screening. A questionnaire and two consecutive fecal immunological tests (FITs) were used as primary screening methods. Subjects who were positive for any of the two tests were referred for further examination with colonoscopy. Neoplasms were removed either colonoscopically or by colectomy. Atypical adenoma and CRC were defined as advanced neoplasms.

Results

A total of 6,971 residents in Dadong Street, Yuexiu District were screened with a questionnaire, and among them, 5,343 underwent at least one FIT. Four thousand and two hundred eleven (60.4%) were female, and 2,760 (39.6%) were male, with a median age of 62.0 years. Questionnaire and FITs identified 1,219 candidates for further examination with colonoscopy, among whom only 647 (53.1%) comply. As of this writing, 623 colonoscopy results were obtained, among which 270 (43.3%) had positive findings. The adenoma detection rate (ADR) was 43.3% (270/623). The ADR was 43.3% (270/623). Of the 270 patients, 10 (3.07%) had CRC, 81 (30.0%) had advanced adenoma, 178 had low-grade adenoma or other benign polyps, one had carcinoid. Except for three advanced CRC, all neoplasms detected were benign or in an early stage.

Conclusions

Our screening program help identified patients with colonic neoplasms at an early stage, precluding them from developing into the malignant disease. The addition of the questionnaire significantly increased the sensitivity of primary screening, while also decreasing the specificity. Long-term results should evaluate the social and economic benefits of this program.

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.

Circulating tumor DNA in patients with colorectal adenomas: assessment of detectability and genetic heterogeneity

Improving early detection of colorectal cancer (CRC) is a key public health priority as adenomas and stage I cancer can be treated with minimally invasive procedures. Population screening strategies based on detection of occult blood in the feces have contributed to enhance detection rates of localized disease, but new approaches based on genetic analyses able to increase specificity and sensitivity could provide additional advantages compared to current screening methodologies. Recently, circulating cell-free DNA (cfDNA) has received much attention as a cancer biomarker for its ability to monitor the progression of advanced disease, predict tumor recurrence and reflect the complex genetic heterogeneity of cancers. Here, we tested whether analysis of cfDNA is a viable tool to enhance detection of colon adenomas. To address this, we assessed a cohort of patients with adenomas and healthy controls using droplet digital PCR (ddPCR) and mutation-specific assays targeted to trunk mutations. Additionally, we performed multiregional, targeted next-generation sequencing (NGS) of adenomas and unmasked extensive heterogeneity, affecting known drivers such as APC, KRAS and mismatch repair (MMR) genes. However, tumor-related mutations were undetectable in patients' plasma. Finally, we employed a preclinical mouse model of Apc-driven intestinal adenomas and confirmed the inability to identify tumor-related alterations via cfDNA, despite the enhanced disease burden displayed by this experimental cancer model. Therefore, we conclude that benign colon lesions display extensive genetic heterogeneity, that they are not prone to release DNA into the circulation and are unlikely to be reliably detected with liquid biopsies, at least with the current technologies.

"Finding the Right FIT": Rural Patient Preferences for Fecal Immunochemical Test (FIT) Characteristics

PURPOSE

Colorectal cancer (CRC) is the third leading cause of cancer death in the United States, yet 1 in 3 Americans have never been screened for CRC. Annual screening using fecal immunochemical tests (FITs) is often a preferred modality in populations experiencing CRC screening disparities. Although multiple studies evaluate the clinical effectiveness of FITs, few studies assess patient preferences toward kit characteristics. We conducted this community-led study to assess patient preferences for FIT characteristics and to use study findings in concert with clinical effectiveness data to inform regional FIT selection.

METHODS

We collaborated with local health system leaders to identify FITs and recruit age eligible (50 to 75 years), English or Spanish speaking community members. Participants completed up to 6 FITs and associated questionnaires and were invited to participate in a follow-up focus group. We used a sequential explanatory mixed-methods design to assess participant preferences and rank FIT kits. First, we used quantitative data from user testing to measure acceptability, ease of completion, and specimen adequacy through a descriptive analysis of 1) fixed response questionnaire items on participant attitudes toward and experiences with FIT kits, and 2) a clinical assessment of adherence to directions regarding collection, packaging, and return of specimens. Second, we analyzed qualitative data from focus groups to refine FIT rankings and gain deeper insight into the pros and cons associated with each tested kit.

FINDINGS

Seventy-six FITs were completed by 18 participants (Range, 3 to 6 kits per participant). Over half (56%, n = 10) of the participants were Hispanic and 50% were female (n = 9). Thirteen participants attended 1 of 3 focus groups. Participants preferred FITs that were single sample, used a probe and vial for sample collection, and had simple, large-font instructions with colorful pictures. Participants reported challenges using paper to catch samples, had difficulty labeling tests, and emphasized the importance of having care team members provide verbal instructions on test completion and follow-up support for patients with abnormal results. FIT rankings from most to least preferred were OC-Light, Hemosure iFOB Test, InSure FIT, QuickVue, OneStep+, and Hemoccult ICT.

CONCLUSIONS

FIT characteristics influenced patient's perceptions of test acceptability and feasibility. Health system leaders, payers, and clinicians should select FITs that are both clinically effective and incorporate patient preferred test characteristics. Consideration of patient preferences may facilitate FIT return, especially in populations at higher risk for experiencing CRC screening disparities.

Filaments with Affinity Binding and Wet Strength Can Be Achieved by Spinning Bifunctional Cellulose Nanofibrils

We demonstrate benzophenone (BP) conjugation via amine-reactive esters onto oxidized cellulosic fibers that were used as precursors, after microfluidization, of photoactive cellulose nanofibrils (CNF). From these fibrils, cellulose I filaments were synthesized by hydrogel spinning in an antisolvent followed by fast biradical UV cross-linking. As a result, the wet BP-CNF filaments retained extensively the original dry strength (a remarkable ∼80% retention). Thus, the principal limitation of these emerging materials was overcome (the wet tensile strength is typically <0.5% of the value measured in dry conditions). Subsequently, antihuman hemoglobin (anti-Hb) antibodies were conjugated onto residual surface carboxyl groups, making the filaments bifunctional for their active groups and properties (wet strength and bioactivity). Optical (surface plasmon resonance) and electroacoustic (quartz crystal microgravimetry) measurements conducted with the bifunctional CNF indicated effective anti-Hb conjugation (2.4 mg m^-2), endowing an excellent sensitivity toward Hb targets (1.7 ± 0.12 mg m^-2) and negligible nonspecific binding. Thus, the anti-Hb biointerface was deployed on filaments that captured Hb efficiently from aqueous matrices (confocal laser microscopy of FITC-labeled antibodies). Significantly, the anti-Hb biointerface was suitable for regeneration, while its sensitivity and selectivity in affinity binding can be tailored by application of blocking copolymers. The developed bifunctional filaments based on nanocellulose offer great promise in detection and affinity binding built upon 1D systems, which can be engineered into other structures for rational use of material and space.

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.

Cancer screening in the United States, 2017: A review of current American Cancer Society guidelines and current issues in cancer screening

Answer questions and earn CME/CNE Each year, the American Cancer Society publishes a summary of its guidelines for early cancer detection, data and trends in cancer screening rates, and select issues related to cancer screening. In this issue of the journal, the authors summarize current American Cancer Society cancer screening guidelines, describe an update of their guideline for using human papillomavirus vaccination for cancer prevention, describe updates in US Preventive Services Task Force recommendations for breast and colorectal cancer screening, discuss interim findings from the UK Collaborative Trial on Ovarian Cancer Screening, and provide the latest data on utilization of cancer screening from the National Health Interview Survey. CA Cancer J Clin 2017;67:100-121. © 2017 American Cancer Society.

Systematic review with meta-analysis: faecal occult blood tests show lower colorectal cancer detection rates in the proximal colon in colonoscopy-verified diagnostic studies

BACKGROUND

The performance of faecal occult blood tests (FOBTs) to screen proximally located colorectal cancer (CRC) has produced inconsistent results.

AIM

To assess in a meta-analysis, the diagnostic accuracy of FOBTs for relative detection of CRC according to anatomical location of CRC.

METHODS

Diagnostic studies including both symptomatic and asymptomatic cohorts assessing performance of FOBTs for CRC were searched from MEDINE and EMBASE. Primary outcome was accuracy of FOBTs according to the anatomical location of CRC. Bivariate random-effects model was used. Subgroup analyses were performed to evaluate test performance of guaiac-based FOBT (gFOBT) and immunochemical-based FOBT (iFOBT).

RESULTS

Thirteen studies, with 17 cohorts, reporting performance of FOBT were included; a total of 26 342 patients (mean age 58.9 years; 58.1% male) underwent both colonoscopy and FOBT. Pooled sensitivity, specificity, positive likelihood ratio and negative likelihood ratio of FOBTs for CRC detection in the proximal colon were 71.2% (95% CI 61.3-79.4%), 93.6% (95% CI 90.7-95.7%), 11.1 (95% CI 7.8-15.8) and 0.3 (95% CI 0.2-0.4) respectively. Corresponding findings for CRC detection in distal colon were 80.1% (95% CI 70.9-87.0%), 93.6% (95% CI 90.7-95.7%), 12.6 (95% CI 8.8-18.1) and 0.2 (95% CI 0.1-0.3). The area-under-curve for FOBT detection for proximal and distal CRC were 90% vs. 94% (P = 0.0143). Both gFOBT and iFOBT showed significantly lower sensitivity but comparable specificity for the detection of proximally located CRC compared with distal CRC.

CONCLUSION

Faecal occult blood tests, both guaiac- and immunochemical-based, show better diagnostic performance for the relative detection of colorectal cancer in the distal colon than in the proximal bowel.

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.

Effect of Ambient Temperature Variations on Positivity of Manual Fecal Immunochemical Tests

INTRODUCTION

In the United States, many fecal occult blood tests are mailed by patients to a laboratory for analysis. Hemoglobin is not stable in feces and can be affected by the heat. Effects of season and ambient temperature on fecal immunochemical tests (FITs) have demonstrated a decrease in positivity rates during the hottest season.

OBJECTIVE

To investigate the potential effect of the average of 4-day ambient maximum temperature variations on the positivity of a single sample, one-time Clinical Laboratory Improvement Amendments (CLIA)-waived FIT.

SETTING

Midwestern tertiary care hospital.

METHODS

Individuals scheduled for a colonoscopy were invited to complete a qualitative FIT prior to their colonoscopy in 2010 and 2011. FITs were read as positive or negative.

RESULTS

Valid FITs were received from 1026 individuals over 25 months. The positivity rate was 10.9%. The mean 4-day average of daily maximum ambient temperatures was calculated including the day of receipt for each sample. Fahrenheit temperatures ranged from 16.0 to 96.8. Based on the odds ratio of 1.04 with a confidence interval of 0.94 to 1.14 for a 10°F increase in temperature, there was no statistically significant evidence of an effect of the preceding maximum average 4-day ambient temperature on FIT positivity.

CONCLUSION

No evidence was found that ambient temperature had an effect on positivity rate over a 25-month period using 4 different qualitative FIT products. Further analysis on effect of ambient temperatures is warranted for the automated FITs and CLIA-waived FITs, including liquid-vial and dry-slide FITs. Primary care providers need to be aware of potential adverse effects of FITs.

Cancer screening in the United States, 2015: a review of current American cancer society guidelines and current issues in cancer screening

Each year, the American Cancer Society (ACS) publishes a summary of its guidelines for early cancer detection along with a report on data and trends in cancer screening rates and select issues related to cancer screening. In this issue of the journal, we summarize current ACS cancer screening guidelines. The latest data on utilization of cancer screening from the National Health Interview Survey (NHIS) also is described, as are several issues related to screening coverage under the Affordable Care Act, including the expansion of the Medicaid program.

Test characteristics of faecal immunochemical tests (FIT) compared with optical colonoscopy

BACKGROUND

Faecal occult blood tests are often the initial test in population-based screening. We aimed to: 1) compare the results of single sample faecal immunochemical tests (FITs) with colonoscopy, and 2) calculate the sensitivity for proximal vs. distal adenomatous polyps or cancer.

METHODS

Individuals scheduled for a colonoscopy were invited to complete a FIT prior to their colonoscopy preparation. FIT results were classified as positive, negative, or invalid. Colonoscopy reports were reviewed and abstracted. Because of product issues, four different FIT manufacturers were used. The test characteristics for each FIT manufacturer were calculated for advanced adenomatous polyps or cancer according to broad reason for colonoscopy (screening or surveillance/diagnostic).

RESULTS

Of those invited, 1,026 individuals (43.9%) completed their colonoscopy and had a valid FIT result. The overall sensitivity of the FITs (95% confidence intervals) was 0.18 (0.10 to 0.28) and specificity was 0.90 (0.87 to 0.91) for advanced adenomas or cancer. The sensitivity for distal lesions was 0.23 (0.11 to 0.38) and for proximal lesions was 0.09 (0.02 to 0.25). The odds ratio of an individual with a distal advanced adenoma or cancer testing positive was 2.68 (1.20 to 5.99). The two individuals with colorectal cancer tested negative, as did one individual with high-grade dysplasia.

CONCLUSIONS

The sensitivity of a single-sample FIT for advanced adenomas or cancer was low. Individuals with distal adenomas had a higher odds of testing positive than those with proximal lesions or no lesions.