Evaluating the Potential of Polygenic Risk Score to Improve Colorectal Cancer Screening

BACKGROUND

Colorectal cancer has high incidence and associated mortality worldwide. Screening programs are recommended for men and women over 50. Intermediate screens such as fecal immunochemical testing (FIT) select patients for colonoscopy with suboptimal sensitivity. Additional biomarkers could improve the current scenario.

METHODS

We included 2,893 individuals with a positive FIT test. They were classified as cases when a high-risk lesion for colorectal cancer was detected after colonoscopy, whereas the control group comprised individuals with low-risk or no lesions. 65 colorectal cancer risk genetic variants were genotyped. Polygenic risk score (PRS) and additive models for risk prediction incorporating sex, age, FIT value, and PRS were generated.

RESULTS

Risk score was higher in cases compared with controls [per allele OR = 1.04; 95% confidence interval (CI), 1.02-1.06; P < 0.0001]. A 2-fold increase in colorectal cancer risk was observed for subjects in the highest decile of risk alleles (≥65), compared with those in the first decile (≤54; OR = 2.22; 95% CI, 1.59-3.12; P < 0.0001). The model combining sex, age, FIT value, and PRS reached the highest accuracy for identifying patients with a high-risk lesion [cross-validated area under the ROC curve (AUROC): 0.64; 95% CI, 0.62-0.66].

CONCLUSIONS

This is the first investigation analyzing PRS in a two-step colorectal cancer screening program. PRS could improve current colorectal cancer screening, most likely for higher at-risk subgroups. However, its capacity is limited to predict colorectal cancer risk status and should be complemented by additional biomarkers.

IMPACT

PRS has capacity for risk stratification of colorectal cancer suggesting its potential for optimizing screening strategies alongside with other biomarkers.

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.

Colon capsule endoscopy versus CT colonography in FIT-positive colorectal cancer screening subjects: a prospective randomised trial-the VICOCA study

BACKGROUND

Colon capsule endoscopy (CCE) and CT colonography (CTC) are minimally invasive techniques for colorectal cancer (CRC) screening. Our objective is to compare CCE and CTC for the identification of patients with colorectal neoplasia among participants in a CRC screening programme with positive faecal immunochemical test (FIT). Primary outcome was to compare the performance of CCE and CTC in detecting patients with neoplastic lesions.

METHODS

The VICOCA study is a prospective, single-centre, randomised trial conducted from March 2014 to May 2016; 662 individuals were invited and 349 were randomised to CCE or CTC before colonoscopy. Endoscopists were blinded to the results of CCE and CTC.

RESULTS

Three hundred forty-nine individuals were included: 173 in the CCE group and 176 in the CTC group. Two hundred ninety individuals agreed to participate: 147 in the CCE group and 143 in the CTC group. In the intention-to-screen analysis, sensitivity, specificity and positive and negative predictive values for the identification of individuals with colorectal neoplasia were 98.1%, 76.6%, 93.7% and 92.0% in the CCE group and 64.9%, 95.7%, 96.8% and 57.7% in the CTC group. In terms of detecting significant neoplastic lesions, the sensitivity of CCE and CTC was 96.1% and 79.3%, respectively. Detection rate for advanced colorectal neoplasm was higher in the CCE group than in the CTC group (100% and 93.1%, respectively; RR = 1.07; p = 0.08). Both CCE and CTC identified all patients with cancer. CCE detected more patients with any lesion than CTC (98.6% and 81.0%, respectively; RR = 1.22; p = 0.002).

CONCLUSION

Although both techniques seem to be similar in detecting patients with advanced colorectal neoplasms, CCE is more sensitive for the detection of any neoplastic lesion.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02081742 . Registered: September 16, 2013.

Identification and Validation of MicroRNA Profiles in Fecal Samples for Detection of Colorectal Cancer

BACKGROUND & AIMS

Screening for colorectal cancer (CRC) is effective in the population at average risk. The most extended strategy in organized programs involves the fecal immunochemical test, which is limited by low sensitivity for the detection of advanced adenomas (AAs). We aimed to identify microRNA (miRNA) signatures in fecal samples that identify patients with AAs or CRC and might be used in noninvasive screening.

METHODS

Our study comprised 4 stages. In the discovery phase, we performed genome-wide miRNA expression profiling of 124 fresh, paired colorectal tumor and nontumor samples (30 CRC; 32 AAs) from patients in Spain. In the technical validation stage, miRNAs with altered expression levels in tumor vs nontumor tissues were quantified by reverse-transcription polymerase chain reaction in fecal samples from a subset of patients included in the discovery phase (n = 39) and individuals without colorectal neoplasms (controls, n = 39). In the clinical validation stage, the miRNAs found to be most significantly up-regulated by quantitative reverse transcription polymerase chain reaction analysis were measured in an independent set of fecal samples (n = 767) from patients with positive results from fecal immunochemical tests in a CRC screening program. Finally, we developed a model to identify patients with advanced neoplasms (CRCs or AAs) based on their miRNA profiles, using findings from colonoscopy as the reference standard.

RESULTS

Among 200 and 324 miRNAs significantly deregulated in CRC and AA tissues, respectively, 7 and 5 of these miRNAs were also found to be deregulated in feces (technical validation). Of them, MIR421, MIR130b-3p, and MIR27a-3p were confirmed to be upregulated in fecal samples from patients with advanced neoplasms. In our model, the combination of fecal level of MIR421, MIR27a-3p, and hemoglobin identified patients with CRC with an area under the curve (AUC) of 0.93, compared with an AUC of 0.67 for fecal hemoglobin concentration alone.

CONCLUSIONS

We found that increased levels of 2 miRNAs and hemoglobin in feces can identify patients with AAs or CRC more accurately than fecal hemoglobin concentration alone. Assays for these miRNAs might be added to fecal tests for the detection of CRC or AAs.

Rate of detection of advanced neoplasms in proximal colon by simulated sigmoidoscopy vs fecal immunochemical tests

BACKGROUND & AIMS

We compared the ability of biennial fecal immunochemical testing (FIT) and one-time sigmoidoscopy to detect colon side-specific advanced neoplasms in a population-based, multicenter, nationwide, randomized controlled trial.

METHODS

We identified asymptomatic men and women, 50-69 years old, through community health registries and randomly assigned them to groups that received a single colonoscopy examination or biennial FIT. Sigmoidoscopy yield was simulated from results obtained from the colonoscopy group, according to the criteria proposed in the UK Flexible Sigmoidoscopy Trial for colonoscopy referral. Patients who underwent FIT and were found to have ≥75 ng hemoglobin/mL were referred for colonoscopy. Data were analyzed from 5059 subjects in the colonoscopy group and 10,507 in the FIT group. The main outcome was rate of detection of any advanced neoplasm proximal to the splenic flexure.

RESULTS

Advanced neoplasms were detected in 317 subjects (6.3%) in the sigmoidoscopy simulation group compared with 288 (2.7%) in the FIT group (odds ratio for sigmoidoscopy, 2.29; 95% confidence interval, 1.93-2.70; P = .0001). Sigmoidoscopy also detected advanced distal neoplasia in a higher percentage of patients than FIT (odds ratio, 2.61; 95% confidence interval, 2.20-3.10; P = .0001). The methods did not differ significantly in identifying patients with advanced proximal neoplasms (odds ratio, 1.17; 95% confidence interval, 0.78-1.76; P = .44). This was probably due to the lower performance of both strategies in detecting patients with proximal lesions (sigmoidoscopy detected these in 19.1% of patients and FIT in 14.9% of patients) vs distal ones (sigmoidoscopy detected these in 86.8% of patients and FIT in 33.5% of patients). Sigmoidoscopy, but not FIT, detected proximal lesions in lower percentages of women (especially those 50-59 years old) than men.

CONCLUSIONS

Sigmoidoscopy and FIT have similar limitations in detecting advanced proximal neoplasms, which depend on patients' characteristics; sigmoidoscopy underperforms for women 50-59 years old. Screening strategies should be designed on the basis of target population to increase effectiveness and cost-effectiveness. ClinicalTrials.gov number: NCT00906997.