Correlating Quantitative Fecal Immunochemical Test Results with Neoplastic Findings on Colonoscopy in a Population-Based Colorectal Cancer Screening Program: A Prospective Study

Feasibility and Colonoscopy Yield Using the Fecal Immunochemical Test (FIT)-Based Colorectal Cancer Screening in a Latin America Country

BACKGROUND & AIMS

Organized colorectal cancer (CRC) screening is not widely practiced in Latin America and the results of regional studies may help overcome barriers for implementation of national screening programs. We aimed to describe the implementation and findings of a fecal immunochemical test (FIT)-based program in Brazil.

METHODS

In a prospective population-based study, asymptomatic individuals (50-75 years old) from Sao Paulo city were invited to undergo FIT for CRC screening. Participants with positive FIT (≥10 μg Hb/g feces) were referred for colonoscopy. Subjects were classified into groups according to the presence of CRC, precursor lesions, and other benign findings, possibly related to bleeding.

RESULTS

Of a total of 9881 subjects, 7.8% had positive FIT and colonoscopy compliance was 68.9% (n = 535). Boston scale was considered adequate in 99% and cecal intubation rate was 99.4%. CRC was diagnosed in 5.9% of the cases, adenoma in 63.2%, advanced adenoma in 31.4%, and advanced neoplasia in 33.0%. Age was positively associated with CRC (P = .03). Higher FIT concentrations were associated with increased detection of CRC (P < .008), advanced adenoma (P < .001), and advanced neoplasia (P < .001).

CONCLUSIONS

Implementation of a FIT-based CRC screening program was feasible in a low-resource setting, and there was a high yield for neoplasia in individuals with a positive FIT. This approach could be used as a model to plan and disseminate organized CRC screening more broadly in Brazil and Latin America.

Pooled rates of adenoma detection by colonoscopy in asymptomatic average-risk individuals with positive fecal immunochemical test: a systematic review and meta-analysis

BACKGROUND AND AIMS

Current adenoma detection rate (ADR) benchmarks for colonoscopy in individuals positive for a fecal immunochemical test (FIT) are ≥45% in men and ≥35% in women. These are based on weak, low-quality evidence. We performed a meta-analysis to ascertain the pooled ADR in FIT-positive colonoscopy.

METHODS

Major databases like PubMed, EMBASE, and Web of Science were searched in October 2021 for studies reporting on ADR of colonoscopy in a FIT-positive population. Meta-analysis was performed by standard methodology using the random-effects model. Heterogeneity was assessed by I² and 95% prediction interval statistics.

RESULTS

Thirty-four high-quality studies that included more than 6 million asymptomatic average-risk individuals were analyzed; 2,655,345 individuals completed a screening FIT test. The pooled FIT screening rate was 69.8% (95% CI, 62.8-76.1), the pooled FIT positivity rate was 5.4% (95% CI, 4.3-6.9), and the colonoscopy completion rate was 85% (95% CI, 82.8-86.9). The pooled ADR was 47.8% (95% CI, 44.1-51.6), pooled advanced ADR was 25.3% (95% CI, 22-29), and the pooled colorectal cancer detection rate was 5.1% (95% CI, 4.4-5.9). The pooled ADR in men was 58.3% (95% CI, 52.8-63.6) and in women was 41.9% (95% CI, 36.4-47.6). The pooled ADR with qualitative FIT assessment was 67.7% (95% CI, 50.7-81), with 1-stool sample FIT was 52.8% (95% CI, 48.8-56.8), and at a cutoff threshold of 100 ng hemoglobin/mL was 52.1% (95% CI, 47-57.1). Based on time-period cumulative analysis, the ADR improved over time from 30.5% (95% CI, 24.6-37.2) to 47.8% (95% CI, 44.1-51.6).

CONCLUSIONS

This meta-analysis supports the current ADR benchmarks for colonoscopy in FIT-positive individuals. Excellent pooled ADR parameters were demonstrated with qualitative assessment of 1 stool sample at a test cutoff value of 100 ng hemoglobin/mL, and ADR per endoscopist improved over time.

PPV and Detection Rate of mt-sDNA Testing, FIT, and CT Colonography for Advanced Neoplasia: A Hierarchic Bayesian Meta-Analysis of the Noninvasive Colorectal Screening Tests

BACKGROUND. Noninvasive tests for colorectal cancer (CRC) screening and prevention limit the need for invasive colonoscopy to follow up positive test results. However, the relative performance characteristics of available noninvasive tests have not yet been adequately compared. OBJECTIVE. We performed a systematic review and meta-analysis to compare the diagnostic performance of the available noninvasive CRC screening tests, including multitarget stool DNA (mt-sDNA) testing, fecal immunochemical testing (FIT), and CT colonography (CTC), with an emphasis on comparison of PPV and detection rate (DR) for advanced neoplasia (AN; encompassing cases of advanced adenomas and CRC). EVIDENCE ACQUISITION. After systematic searches of MEDLINE and Google Scholar databases, 10 mt-sDNA, 27 CTC, and 88 FIT published screening studies involving 25,132, 33,493, and 2,355,958 asymptomatic adults, respectively, were included. Meta-analysis with hierarchic Bayesian modeling was conducted in accordance with Cochrane Collaboration and PRISMA guidelines to determine test positivity rates (TPRs) leading to optical colonoscopy, as well as PPVs and DRs for both AN and CRC. Different positivity thresholds were considered for FIT and CTC. EVIDENCE SYNTHESIS. Point estimates (with 95% credible intervals) from pooled Bayesian meta-analysis combining all thresholds for FIT and stratifying CTC results by a polyp size threshold of 6 mm or larger (CTC6) and 10 mm or larger (CTC10) were calculated. TPR was 13.5% (10.9-16.6%) for mt-sDNA testing, 6.4% (5.8-7.2%) for FIT, 13.4% (11.4-15.6%) for CTC6, and 6.6% (5.2-7.7%) for CTC10. AN PPV was 26.9% (95% credible interval, 21.8-33.2%) for mt-sDNA testing, 31.8% (29.3-34.5%) for FIT, 34.4% (27.2-41.0%) for CTC6, and 61.0% (54.0-70.0%) for CTC10. CRC PPV was 2.4% (1.5-3.9%) for mt-sDNA testing, 4.9% (4.3-5.3%) for FIT, 3.5% (2.5-4.8%) for CTC6, and 6.0% (4.3-8.0%) for CTC10. The DR for AN was 3.4% (95% credible interval, 2.5-4.8%) for mt-SDNA, 2.0% (1.8-2.3%) for FIT, 4.8% (4.0-6.5%) for CTC6, and 4.0% (3.0-4.6%) for CTC10. When FIT is restricted to a lower threshold (< 10 μg Hb/g feces), its performance profile is similar to that of mt-sDNA testing, although available data are limited. AN PPV odds ratios (relative to CTC10 as the reference) were 0.24 (95% credible interval, 0.17-0.33) for mt-sDNA testing, 0.30 (0.24-0.45) for FIT, and 0.33 (0.25-0.47) for CTC6. CONCLUSION. Among noninvasive CRC screening tests, CTC with a polyp size threshold of 10 mm or larger most effectively targets AN, preserving detection while also decreasing unnecessary colonoscopies compared with mt-sDNA testing and FIT. CLINICAL IMPACT. CTC performed with a polyp size threshold for colonoscopy referral set at 10 mm or larger represents the most effective and efficient noninvasive screening test for CRC prevention and detection.

Colorectal adenocarcinomas diagnosed following a negative faecal immunochemical test show high-risk pathological features in a colon screening programme

AIMS

The faecal immunochemical test (FIT) is used every 2 years to screen average-risk British Columbians aged 50-74 years, with follow-up colonoscopy for positive results. Non-screen-detected colorectal adenocarcinomas are defined as those detected within 25 months following a negative FIT. We aimed to more clearly characterise these malignancies.

METHODS AND RESULTS

A medical chart and focused pathology review of colorectal malignancies from 926 individuals who completed FIT in the British Columbia Colon Screening Program in 2014, and whose pathology reports were available for review, was conducted. This cohort was divided into two groups: individuals with colorectal adenocarcinomas diagnosed following a positive FIT (screen-detected) and individuals with colorectal adenocarcinoma diagnosed within 25 months of a negative FIT (FIT-interval cancers). Rates of clinically relevant pathological parameters, as outlined in the American Joint Committee on Cancer (AJCC), 8th edition, were compared between the screen-detected and FIT-interval cancer groups. A total of 876 screen-detected and 50 FIT-interval cancers were identified. FIT-interval cancers exhibited higher rates of high-grade differentiation (including poorly differentiated and undifferentiated cases; P < 0.01) and aggressive histotype (signet ring cell and mucinous carcinomas; P < 0.01) than did screen-detected cancers after Bonferroni correction. Colorectal adenocarcinoma diagnosed after a negative FIT may therefore be associated with worse prognostic determinants than screen-detected cancers.

CONCLUSION

FIT-interval cancers are associated with high-risk pathological features; the possibility that more aggressive, fast-growing lesions which arise in the interval after truly negative FITs cannot be ruled out. Further study of a larger cohort of FIT-interval cancers controlling for interaction among the different pathologic parameters will be undertaken.

Fecal immunochemical test in colorectal cancer screening: Colonoscopy findings by different cut-off levels

BACKGROUND AND AIM

Fecal immunochemical test (FIT) is used in colorectal cancer (CRC) screening, but number of tests and cut-off level differ by program. The aim was to evaluate CRC screening with two FIT samples in average-risk 60-year-old men and women and to investigate hemoglobin (Hb) level in correlation to adenoma characteristics.

METHODS

We analyzed a cohort from Screening of Swedish Colons trial where participants with at least one of two FIT samples ≥10 μg Hb/g are offered colonoscopy. FIT levels and colonoscopy findings were assessed in multivariable analyses. Cut-off levels 10-80 μg Hb/g for one and two samples were assessed. FIT levels and advanced neoplasia (AN) were investigated by gender.

RESULTS

A total of 12 383 participated and 1182 positives (551 women) completed colonoscopy diagnosing 27 (2.3%) CRC and 269 (23%) advanced adenomas (AA). Median FIT level was 241.0 and 23.8 for CRC and AA compared with 13.4-15.8 in other subgroups (P = 0.002) correlating with adenoma size (P = 0.038). CRC was detected in 22 and 19 subjects for the first sample at cut-off 20 and 40 μg Hb/g, compared with 20 and 17 for the mean of two samples at cut-off 40 and 80 μg Hb/g (P < 0.05). Men had more AN (CRC + AA), (P = 0.003). In women, similar number of AN would be detected with cut-off lowered from 40 to 20 or from 80 to 40 μg Hb/g, requiring additional 26-34% colonoscopies.

CONCLUSION

In average-risk 60-year-olds, FIT was higher in participants with AN and correlated with adenoma size. FIT screening with one sample at low cut-off detected more CRC than two samples at higher cut-off. Applying lower cut-off in women to equalize gender differences in AN would result in considerable increase in colonoscopy workload.