SnoRNA profiling in colorectal cancer and assessment of non-invasive biomarker capacity by ddPCR in fecal samples.

Small nucleolar RNAs (snoRNAs) have been identified dysregulated in several pathologies, and these alterations can be detected in tissues and in circulation. The main aim of this study was to analyze the whole snoRNome in advanced colorectal neoplasms and to identify new potential non-invasive snoRNA-based biomarkers in fecal samples by different analytical approaches. SNORA51, SNORD15B, SNORA54, SNORD12B, SNORD12C, SNORD72, SNORD89, and several members of SNORD115 and SNORD116 clusters were consistently deregulated in both tissue sets. After technical validation, SNORA51 and SNORD15B were detected in FIT+ samples. SNORA51 was significantly upregulated in FIT+ samples from CRC patients compared to healthy controls. This upregulation, together with the fecal hemoglobin concentration, was sufficient to identify, among FIT+ individuals, patients with CRC (AUC = 0.86) and individuals with advanced adenomas (AUC = 0.68). These findings portray snoRNAs as an alternative source of candidates for further studies and SNORA51 appears as a potential non-invasive biomarker for CRC detection.

Fecal MicroRNA-Based Algorithm Increases Effectiveness of Fecal Immunochemical Test-Based Screening for Colorectal Cancer.

BACKGROUND & AIMS: An algorithm based on fecal levels of 2 microRNAs (miR-421 and miR-27a-3p), fecal hemoglobin concentration, and patient age and sex can identify patients with advanced colorectal neoplasia. We investigated whether this algorithm, called miRFec, could increase effectiveness and efficiency of fecal immunochemical test (FIT)-based colorectal cancer (CRC) screening programs. METHODS: We obtained data and fecal samples from 767 persons with a positive result from the FIT who then underwent colonoscopy examination while participating a population-based CRC screening program, from March 2011 through May 2017 in Barcelona, Spain. Fecal miRNAs were isolated from the buffer contained in the original FIT collection device and analyzed by quantitative reverse transcription PCR. Aims were to evaluate the usefulness of the miRFec algorithm in identifying persons at greatest risk for CRC who should be prioritized for colonoscopy examination and individuals at low risk for whom colonoscopy could be avoided. RESULTS: Of the 767 study subjects, 414 (54.0%) were found by colonoscopy to have advanced colorectal neoplasia (67 with CRC and 347 with advanced adenomas) and 353 (46.0%) were found to have either non-advanced adenomas (n = 136) or a normal examination (n = 217). MiRFec algorithm scores (1-4) were independently associated with the presence of advanced colorectal neoplasia (P < .001). The miRFec algorithm differentiated patients with CRC from those with non-advanced adenomas or normal colonoscopy with an area under the receiver operating characteristic curve of 90% (95% CI, 86-94). Subjects with miRFec scores in the 4th quartile (above 3.09, high-risk group) were 8-fold more likely to have advanced colorectal neoplasia than subjects with miRFec scores in the 1st quartile (below 2.14, low-risk group). Subjects in the low-risk group had a positive predictive value below 30% for detection of advanced colorectal neoplasia. When we used a 50% specificity cut-off value, the miRFec algorithm identified 97% of patients with CRC and would allow 264 subjects (34.4%) to avoid colonoscopy examination. CONCLUSIONS: An algorithm based on fecal levels of 2 miRNAs and hemoglobin, patient age and sex (miRFec) differentiated patients with CRC from those with non-advanced adenomas or normal colonoscopy with an area under the receiver operating characteristic curve value of 90% and avoided 34% of colonoscopies. Inclusion of this algorithm in FIT-based CRC screening programs could increase their effectiveness and efficiency.

False-negative rate cannot be reduced by lowering the haemoglobin concentration cut-off in colorectal cancer screening using faecal immunochemical test.

The aim of this study was to analyse false-negative (FN) results of the faecal immunochemical test (FIT) and its determinants in a colorectal cancer screening programme in Catalonia. We carried out a cross-sectional study among 218 screenees with a negative FIT result who agreed to undergo a colonoscopy. A false-negative result was defined as the detection, at colonoscopy, of intermediate/high-risk polyps or colorectal cancer in a patient with a previous negative FIT (<20 µgHb/g). Multivariate logistic regression models were constructed to identify sociodemographic (sex, age) and screening variables (quantitative faecal haemoglobin, colonoscopy findings) related to FN results. Adjusted odds ratios and their 95% confidence intervals were estimated. There were 15.6% FN FIT results. Faecal haemoglobin was undetected in 45.5% of these results and was below 4 µgHb/g in 94.0% of the individuals with a FN result. About 60% of the lesions were located in the proximal colon, whereas the expected percentage was 30%. Decreasing the positivity threshold of FIT does not increase the detection rate of advanced neoplasia, but may increase the costs and potential adverse effects.

Prescription drugs associated with false-positive results when using faecal immunochemical tests for colorectal cancer screening.

BACKGROUND: The most common side effect in population screening programmes is a false-positive result which leads to unnecessary risks and costs. AIMS: To identify factors associated with false-positive results in a colorectal cancer screening programme with the faecal immunochemical test (FIT). METHODS: Cross-sectional study of 472 participants with a positive FIT who underwent colonoscopy for confirmation of diagnosis between 2013 and 2014. A false-positive result was defined as having a positive FIT (≥20µg haemoglobin per gram of faeces) and follow-up colonoscopy without intermediate/high-risk lesions or cancer. RESULTS: Women showed a two-fold increased likelihood of a false-positive result compared with men (adjusted OR, 2.3; 95%CI, 1.5-3.4), but no female-specific factor was identified. The other variables associated with a false-positive result were successive screening (adjusted OR, 1.5; 95%CI, 1.0-2.2), anal disorders (adjusted OR, 3.1; 95%CI, 2.1-4.5) and the use of proton pump inhibitors (adjusted OR, 1.8; 95%CI, 1.1-2.9). Successive screening and proton pump inhibitor use were associated with FP in men. None of the other drugs were related to a false-positive FIT. CONCLUSION: Concurrent use of proton pump inhibitors at the time of FIT might increase the likelihood of a false-positive result. Further investigation is needed to determine whether discontinuing them could decrease the false-positive rate.