A True Positive and a False Negative? The Dilemma of Negative Colonoscopy After a Positive Fecal Occult Blood Test

Polymorphic Single-Nucleotide Variants in miRNA Genes and the Susceptibility to Colorectal Cancer: Combined Evaluation by Pairwise and Network Meta-Analysis, Thakkinstian's Algorithm and FPRP Criterium

BACKGROUND

Considerable epidemiological studies have examined the correlation between polymorphic single-nucleotide variants (SNPs) in miRNA genes and colorectal carcinoma (CRC) risk, yielding inconsistent results. Herein, we sought to systematically investigate the association between miRNA-SNPs and CRC susceptibility by combined evaluation using pairwise and network meta-analysis, the FPRP analysis (false positive report probability), and the Thakkinstian's algorithm.

METHODS

The MEDLINE, EMBASE, WOS, and Cochrane Library databases were searched through May 2024 to find relevant association literatures. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were computed by the pairwise meta-analysis. Network meta-analysis and the Thakkinstian's method were applied for determining the potentially optimal genetic models; additionally, the FPRP was used to identify noteworthy associations.

RESULTS

Totally, 39 case-control trials involving 18,028 CRC cases, and 21,816 normal participants were included in the study. Eleven SNPs within nine genes were examined for their predisposition to CRC. miR-27a (rs895819) was found to significantly increase CRC risk among overall population (OR 1.58, 95% CI: 1.32-1.89) and Asians (OR 1.62, 95% CI: 1.31-2.01), with the recessive models identified as the optimal models. Furthermore, miR-196a2 (rs11614913), miR-143/145 (rs41291957), and miR-34b/c (rs4938723) were significantly related to reduced CRC risk among Asian descendants under the optimal dominant (OR 0.75, 95% CI: 0.65-0.86), recessive (OR 0.72, 95% CI: 0.60-0.85), and recessive models (OR 0.69, 95% CI: 0.56-0.85), respectively. The results were also proposed by the network meta-analysis or the Thakkinstian's method and confirmed by the FPRP criterion.

CONCLUSION

The miR-27a (rs895819) is correlated with elevated CRC risk among overall population and Asians, and the recessive model is found to be optimal for predicting CRC risk. Additionally, the miR-196a2 (rs11614913), miR-143/145 (rs41291957), and miR-34b/c (rs4938723), with the dominant, recessive, and recessive models identified as the optimal, might confer protective effects against CRC among Asians.

Interval Advanced Adenomas and Neoplasia in Patients with Negative Colonoscopy Following Positive Stool-Based Colorectal Cancer Screening Test

BACKGROUND/AIMS

Fecal occult blood test (FOBT) and fecal immunohistochemical test (FIT) are used for colorectal cancer (CRC) screening. However, when no adenomas are found following a positive FOBT/FIT, the future risk of advanced adenomas or colorectal cancer (CRC) is unclear. We determined the incidence and determinants of advanced adenomas or CRC after a negative index colonoscopy following a positive FOBT/FIT.

METHODS

We identified patients in the Harris Health System (Houston, Texas) who underwent a colonoscopy following a positive FOBT/FIT from 01/2010 to 01/2013. We compared the incidence rates of advanced adenomas (≥ 1 cm, villous histopathology, or high-grade dysplasia) or CRC through 12/2023 for patients without polyps on index colonoscopy (negative colonoscopy) to patients with polyps (positive colonoscopy). We examined risk factors for incident adenomas using Cox regression models.

RESULTS

Of 2096 patients, 1293 (61.7%) had negative index colonoscopy and 803 (38.3%) had positive index colonoscopy. Overall, 411 patients (19.6%) underwent subsequent colonoscopy with incident adenomas in 241 patients and no incident CRC over mean 12.5 years. The incidence rate of advanced adenomas was 2.08 per 100 person-years after positive index colonoscopy compared to 0.65 per 100 person-years after negative index colonoscopy (age-adjusted incidence rate ratio 3.08, 95% CI 1.27-7.48). Non-Hispanic white race was the strongest risk factor for incident adenomas among patients with negative index colonoscopy.

CONCLUSIONS

We found a low likelihood of advanced adenomas and no interval CRC following negative index colonoscopy after positive FOBT/FIT. Non-Hispanic white race was a risk factor for incident adenomas, and these patients may warrant closer surveillance.

Utility of Stool-Based Tests for Colorectal Cancer Detection: A Comprehensive Review

Colorectal cancer (CRC) is a significant global health issue where early detection is crucial for improving treatment outcomes and survival rates. This comprehensive review assesses the utility of stool-based tests in CRC screening, including traditional fecal occult blood tests (FOBT), both chemical (gFOBT) and immunochemical techniques (FIT), as well as multitarget stool DNA (mt-sDNA) as a novel and promising biomarker. The advancements, limitations and the impact of false positives and negatives of these methods are examined. The review analyzed various studies on current screening methods, focusing on laboratory tests and biomarkers. Findings indicate that while FIT and mt-sDNA tests offer enhanced sensitivity and specificity over traditional guaiac-based FOBT, they also come with higher costs and potential for increased false positives. FIT shows better patient adherence due to its ease to use, but incorrect usage and interpretation of FOBT can lead to significant diagnostic errors. In conclusion, despite the improvements in FOBT methods like FIT in CRC detection, careful consideration of each method's benefits and drawbacks is essential. Effective CRC screening programs should combine various methods tailored to specific population needs, aiming for early detection and reduced mortality rates.

Adenoma location, size, and morphology are risk factors for FOBT false-negative results in inpatients with advanced colorectal adenoma

Recently, advanced adenoma (AA) has been recognized as a target for colorectal cancer (CRC) screening. However, the fecal occult blood test (FOBT), the primary non-invasive screening method, shows limited sensitivity in detecting AA. This study investigates the relationship between adenoma characteristics and FOBT false-negative results. In a retrospective cohort study conducted from 2015 to 2022, we examined 342 inpatients with AA who underwent colonoscopy and received qualitative FOBT. FOBT sensitivity was analyzed about various adenoma characteristics, and logistic regression models were employed to investigate the relationship between adenoma features and FOBT false-negative outcomes. FOBT sensitivity in AA inpatients was 52.63%. Significant differences in sensitivity were observed based on adenoma location (left vs. right), morphology (with or without pedunculation), and size (≤ 10 mm vs. > 10 mm). After adjusting for several potential confounders, FOBT showed a reduced false-negative rate in AA with large-sized (OR, 0.49; 95% CI 0.31-0.77), left-sided location (OR, 0.53; 95% CI 0.31-0.89), and pedunculated morphology (OR, 0.73; 95% CI 0.43-1.24). AA with large size, left-sided location, and pedunculated morphology independently contribute to a decreased rate of FOBT false-negative results. However, these adenoma characteristics are not actively modifiable. Therefore, novel non-invasive methods are needed to improve AA detection accuracy.

Multiple Negative Fecal Immunochemical Tests Reduce Risk of Advanced Neoplasia in a Colonoscopy Surveillance Program

BACKGROUND & AIMS

In above-average-risk individuals undergoing colonoscopy-based surveillance for colorectal cancer (CRC), screening with fecal immunochemical tests (FIT) between colonoscopies might facilitate personalization of surveillance intervals. Because a negative FIT is associated with a reduced risk for CRC, we examined the relationship between number of rounds of negative FIT and risk for advanced neoplasia in individuals undergoing surveillance colonoscopy.

METHODS

We conducted a retrospective cohort study on 4021 surveillance intervals in 3369 individuals (50-74 years), who had completed a 2-sample FIT between colonoscopies, from 1 to 4 rounds at 1-2 yearly intervals, each with a negative result (<20 μg hemoglobin/g feces). Incidence of advanced neoplasia (CRC or advanced adenoma) was determined at the follow-up colonoscopy. Competing-risk regression was used to assess the association between multiple negative FIT results and the risk of advanced neoplasia within 2 years.

RESULTS

The incidence of advanced neoplasia in the cohort was 9.9% and decreased with increasing numbers of rounds of negative FIT results: 11.1% after 1 negative FIT to 5.7% after 4 negative FIT. The risk of advanced neoplasia was significantly lower in participants with 3 (subdistribution hazard ratio, 0.50; 95% confidence interval, 0.24-0.97) and 4 (subdistribution hazard ratio, 0.33; 95% confidence interval, 0.15-0.73) rounds of negative FIT compared with only 1 negative FIT.

CONCLUSIONS

There was a low risk of advanced neoplasia after multiple rounds of negative FIT in above-average-risk people undergoing surveillance with no neoplasia or nonadvanced adenoma at prior colonoscopy. This supports the use of interval FIT to personalize surveillance by lengthening colonoscopy intervals following multiple negative FIT results.