Colorectal Cancer Screening Methods Research Articles

New methods for colorectal cancer screening

New methods for colorectal cancer screening

Application of fecal immunochemical test in colorectal cancer screening: A community-based, cross-sectional study in average-risk individuals in Hainan.

The incidence of colorectal cancer (CRC) in China is steadily rising, with a high proportion of advanced-stage diagnoses. This highlights the significance of early detection and prevention measures to enhance survival rates. Fecal immunochemical testing (FIT) is a globally recommended CRC screening method; however, limited research has been conducted on its application in Hainan. To assess the efficacy and adherence of FIT screening among average-risk individuals in Hainan, while also examining the risk factors associated with positive FIT results. This population-based cross-sectional study implemented FIT screening for CRC in 2000 asymptomatic participants aged 40-75 years from five cities and 21 community health centers in Hainan Province. The study was conducted from August 2022 to April 2023, employing a stratified sampling method to select participants. Individuals with positive FIT results subsequently underwent colonoscopy. Positive predictive values for confirmed CRC and advanced adenoma were calculated, and the relationship between relevant variables and positive FIT results was analyzed using χ 2 tests and multivariate logistic regression. A total of 1788 participants completed the FIT screening, with a median age of 57 years (interquartile range: 40-75). Among them, 503 (28.1%) were males, and 1285 (71.9%) were females, resulting in an 89.4% compliance rate for FIT screening. The overall positivity rate of FIT was 4.4% [79 out of 1788; 95% confidence interval (CI): 3%-5%]. The specific positivity rates for Haikou, Sanya, Orient City, Qionghai City, and Wuzhishan City were 9.6% (45 of 468; 95%CI: 8%-11%), 1.3% (6 of 445; 95%CI: 0.1%-3.1%), 2.7% (8 of 293; 95%CI: 1.2%-4.3%), 3.3% (9 of 276; 95%CI: 1.0%-6.3%), and 4.2% (11 of 406; 95%CI: 1.2%-7.3%), respectively. Significant associations were found between age, dietary habits, and positive FIT results. Out of the 79 participants with positive FIT results, 55 underwent colonoscopy, demonstrating an 82.2% compliance rate. Among them, 10 had a clean gastrointestinal tract, 43 had polyps or adenomas, and 2 were confirmed to have CRC, yielding a positive predictive value of 3.6% (95%CI: 0.9%-4.2%). Among the 43 participants with polyps or adenomas, 8 were diagnosed with advanced adenomas, resulting in an advanced adenoma rate of 14.5% (95%CI: 10.1%-17.7%). In the Hainan region, FIT screening for CRC among asymptomatic individuals at average risk is feasible and well-received.

Effectiveness of colonoscopy, immune fecal occult blood testing, and risk-graded screening strategies in colorectal cancer screening.

Colorectal cancer (CRC) is one of the most common malignant tumors, and early screening is crucial to improving the survival rate of patients. The combination of colonoscopy and immune fecal occult blood detection has garnered significant attention as a novel method for CRC screening. Colonoscopy and fecal occult blood tests, when combined, can improve screening accuracy and early detection rates, thereby facilitating early intervention and treatment. However, certain risks and costs accompany it, making the establishment of a risk classification model crucial for accurate classification and management of screened subjects. To evaluate the feasibility and effectiveness of colonoscopy, immune fecal occult blood test (FIT), and risk-graded screening strategies in CRC screening. Based on the randomized controlled trial of CRC screening in the population conducted by our hospital May 2020 to May 2023, participants who met the requirements were randomly assigned to a colonoscopy group, an FIT group, or a graded screening group at a ratio of 1:2:2 (after risk assessment, the high-risk group received colonoscopy, the low-risk group received an FIT test, and the FIT-positive group received colonoscopy). The three groups received CRC screening with different protocols, among which the colonoscopy group only received baseline screening, and the FIT group and the graded screening group received annual follow-up screening based on baseline screening. The primary outcome was the detection rate of advanced tumors, including CRC and advanced adenoma. The population participation rate, advanced tumor detection rate, and colonoscopy load of the three screening programs were compared. A total of 19373 subjects who met the inclusion and exclusion criteria were enrolled, including 8082 males (41.7%) and 11291 females (58.3%). The mean age was 60.05 ± 6.5 years. Among them, 3883 patients were enrolled in the colonoscopy group, 7793 in the FIT group, and 7697 in the graded screening group. Two rounds of follow-up screening were completed in the FIT group and the graded screening group. The graded screening group (89.2%) and the colonoscopy group (42.3%) had the lowest overall screening participation rates, while the FIT group had the highest (99.3%). The results of the intentional analysis showed that the detection rate of advanced tumors in the colonoscopy group was greater than that of the FIT group [2.76% vs 2.17%, odds ratio (OR) = 1.30, 95% confidence interval (CI): 1.01-1.65, P = 0.037]. There was no significant difference in the detection rate of advanced tumors between the colonoscopy group and the graded screening group (2.76% vs 2.35%, OR = 1.9, 95%CI: 0.93-1.51, P = 0.156), as well as between the graded screening group and the FIT group (2.35% vs 2.17%, OR = 1.09%, 95%CI: 0.88-1.34, P = 0.440). The number of colonoscopy examinations required for each patient with advanced tumors was used as an index to evaluate the colonoscopy load during population screening. The graded screening group had the highest colonoscopy load (15.4 times), followed by the colonoscopy group (10.2 times), and the FIT group had the lowest (7.8 times). A hierarchical screening strategy based on CRC risk assessment is feasible for screening for CRC in the population. It can be used as an effective supplement to traditional colonoscopy and FIT screening programs.

Integrating plasma proteome with genome reveals novel protein biomarkers in colorectal cancer.

Biomarkers for colorectal cancer (CRC) can complement population screening methods, but so far, few plasma proteins have been identified as biomarkers for CRC. This study aims to identify potential protein biomarkers and therapeutic targets for CRC within the proteome range. We extracted summary-level data of circulating protein from 7 published genome-wide association studies (GWASs) of plasma proteome for Mendelian randomization (MR), summary-data-based MR (SMR), and co-localization analyses to screen and validate proteins with causal effects in CRC. In addition, we further conducted druggability evaluation, prognosis analysis at the transcriptional level, and enrichment expression at the single-cell level, highlighting the important role of these plasma protein biomarkers in CRC. We identified 117 plasma protein biomarkers associated with CRC risk, with 9 proteins showing stronger genetic correlations in Bayesian co-localization (PP.H4 > 0.70). Further, we found 26 protein-coding genes already used in targeted drug development and may potentially become therapeutic targets for CRC. In prognosis analysis, the encoding genes of plasma proteins exhibited consistent effects with MR analysis and can serve as prognostic biomarkers for CRC. Additionally, we also found that the differentially expressed proteins are mainly expressed in fibroblasts, endothelial cells, macrophages, and T cells. Our study has identified plasma protein biomarkers associated with CRC risk, which may complement population screening methods for CRC and achieve more precise treatment for patients.

Bias due to coarsening of time intervals in the inference for the effectiveness of colorectal cancer screening.

Observational studies are frequently used to estimate the comparative effectiveness of different colorectal cancer (CRC) screening methods due to the practical limitations and time needed to conduct large clinical trials. However, time-varying confounders, e.g. polyp detection in the last screening, can bias statistical results. Recently, generalized methods, or G-methods, have been used for the analysis of observational studies of CRC screening, given their ability to account for such time-varying confounders. Discretization, or the process of converting continuous functions into discrete counterparts, is required for G-methods when the treatment and outcomes are assessed at a continuous scale. This paper evaluates the interplay between time-varying confounding and discretization, which can induce bias in assessing screening effectiveness. We investigate this bias in evaluating the effect of different CRC screening methods that differ from each other in typical screening frequency. First, using theory, we establish the direction of the bias. Then, we use simulations of hypothetical settings to study the bias magnitude for varying levels of discretization, frequency of screening and length of the study period. We develop a method to assess possible bias due to coarsening in simulated situations. The proposed method can inform future studies of screening effectiveness, especially for CRC, by determining the choice of interval lengths where data are discretized to minimize bias due to coarsening while balancing computational costs.

Non-invasive colorectal cancer detection using multimodal deep learning ensemble classifier.

3066 Background: The demand for alternative, non-invasive methods for colorectal cancer (CRC) screening is substantial. Cell-free DNA (cfDNA) whole genome sequencing (WGS) offers a promising avenue, utilizing diverse fragmentomic data. We aimed to develop a new approach: integrating fragment end motif by size (FEMS) with genomic coverage (COV) of cfDNA to enhance CRC screening. Methods: Participants were comprised of 1,506 colonoscopy verified normal samples, 130 advanced adenoma (AA) patients, 302 CRC patients (stage I: 28.5%, stage II: 25.5%, stage III: 31.1%, stage IV: 14.2%, unknown: 0.7%). We generated low depth cfDNA-WGS data (a minimum 40 million reads per sample) using the Novaseq 6000 sequencer. We minimized batch bias by normalizing with the same samples for each experimental batch. The development set comprised 1,332 samples (1,023 normal, 103 AA, and 206 CRC), while the validation set consisted of 606 samples (483 normal, 27 AA, and 96 CRC). Results: Our new algorithm achieved 84.0% sensitivity (95% CI: 81%-86%) for CRC and 69.9% (95% CI: 66%-81%) for AA in the development set, with a specificity of 90.0%. These findings were consistent in the external set with 84.9% specificity (95% CI: 82%-88%) and sensitivities of 80.2% (95% CI: 72%-88%) and 63.0% (95% CI: 44%-82%) for CRC and AA, respectively. The sensitivities across stages (Stage I: 80%, Stage II: 86.8%, Stage III: 78.8%, Stage IV: 96.7%) were similarly reflected in the validation sets (Stage I: 74%, Stage II: 83%, Stage III: 79%, Stage IV: 92%). Conclusions: Our multimodal deep learning model shows promise for accurate non-invasive colon cancer and AA detection using low-coverage cfDNA WGS. Its strong performance in detecting not only CRC but also AA lesions suggests its potential for early intervention and improved patient outcomes. The use of colonoscopy-verified normal samples strengthens the study's credibility and paves the way for future clinical translation.

A multi-center study for colorectal cancer early detection among patients with high-risk disease using a cell-free fragmentomics assay.

3613 Background: Colorectal cancer (CRC) is the third most prevalent and the second deadliest cancer globally, accounting for an estimated 1,926,000 new cases and 903,800 deaths in the year 2022 alone. It's also established that chronic inflammatory conditions, such as Crohn's disease and ulcerative colitis, elevate the risk of developing CRC. Therefore, a timely CRC diagnosis for patients with colorectal disease can significantly improve their prognosis and therefore reduce cancer-related mortalities. Methods: In this study, we enrolled a total of 167 patients diagnosed with CRC (stages I: 43, II: 55, III: 56, IV: 13) and 217 patients with benign colorectal disease (BCD), from five participating hospitals. All participants underwent colonoscopy procedures, and their CRC or BCD status was pathologically confirmed. The development of the cancer detection model was based on a training cohort of 98 CRC patients and 131 BCD patients from three hospitals, and the evaluation of the model's performance was carried out on an independent test cohort comprising 69 CRC patients and 96 BCD patients from the remaining two hospitals. The predictive model leveraged cell-free fragmentomics profiling, employing low-pass whole-genome sequencing (WGS) on pre-operative plasma samples to identify CRC. Results: The early detection model exhibited remarkable efficacy in differentiating CRC patients from those with BCD, achieving an Area Under the Curve (AUC) of 0.930 in the training cohort and a nearly equivalent AUC of 0.926 in the independent test cohort. By applying the same cutoff determined in the training cohort, our model demonstrated a high sensitivity (91.8% in the training cohort and 91.3% in the test cohort) and a satisfactory specificity (78.6% in the training cohort and 82.3% in the test cohort). Notably, the model showed consistent and robust performance across various CRC characteristics, including tumor location, histology subtypes, grades, and mismatch repair deficiency status in both cohorts. Moreover, our model outperformed traditional CRC screening methods such as the fecal immunochemical test, carcinoembryonic antigen (CEA), and CA19-9, which achieved AUCs of 0.742, 0.720, and 0.543, respectively. Further validation was conducted using an additional cohort of 31 patients with advanced colorectal adenoma (advCRA), where the model achieved an AUC of 0.846 and a 66.7% sensitivity for distinguishing advCRA from BCD. Conclusions: The study introduces a non-invasive, cell-free fragmentomics assay that incorporates low-pass WGS and machine learning algorithms, demonstrating significant clinical potential in accurately distinguishing CRC and BCD patients. Our innovative approach offers a promising alternative to traditional screening methods that can improve early CRC detection, enhance CRC patient outcomes, and reduce mortality rates.

Improving Fecal Immunochemical Test Collection for Colorectal Cancer Screening During the COVID-19 Pandemic.

Colonoscopy is a first-line method for colorectal cancer (CRC) screening. However, cost-effective noninvasive tests, such as high-sensitivity guaiac-based fecal occult blood test (gFOBT) and fecal immunochemical test (FIT), are also used. The COVID-19 pandemic had a substantial negative impact on CRC screening rates. The James A. Haley Veterans Affairs Hospital (JAHVAH) continued socially distant CRC screening using FITs, but encountered inefficiencies due to high rates of incorrectly collected FIT samples. A quality improvement (QI) project was conducted to increase correctly collected and testable FIT kits upon initial laboratory submission. The ambulatory QI project sought out root causes for incorrectly returned FITs and proposed Plan-Do-Study-Act (PDSA) cycles based on a series of approved action plans. A multidisciplinary team of laboratory, nursing, administrative, and primary care staff worked together to discover 6 major root causes. Our multipronged PDSA cycle attempted to set up redundant patient reminders, centralize the FIT dispersal process, and make the patient-FIT interface more user-friendly. All PDSA solutions were implemented over 4 months. Lack of collection date was the most common reason for incorrectly returned FIT kits and the focus of PDSA improvements. The rate of FITs with missing collection dates dropped from 24% prior to PDSA to 14% in April 2021. The rate of correctly returned FIT kits rose from 38% before the project to 72% afterwards, surpassing the 20% improvement goal. FIT is a useful method for CRC screening that can be particularly helpful when in-person visits are limited, as seen during the COVID-19 pandemic. The increase in demand for FITs during the pandemic revealed process deficiencies and gave JAHVAH an opportunity to improve workflow.

Screening for colorectal cancer: Study on the shedding cells of feces.

The objective of this study was to explore the enrichment efficiency of an improved fecal exfoliated cell enrichment method and its application in colorectal cancer screening. Samples were collected from a cohort of 100 colorectal cancer patients being treated at the First Hospital of Hebei Medical University from January 2021 to June 2022. Patient samples were equally divided between control and experimental groups corresponding to the enrichment method being applied to the fecal exfoliated cells. Samples consisted of natural stool and bowel cleansing enema solution samples. The control group received the traditional three-layer integrated screen method, and the experimental group used nano-Fe3O4 folic acid magnetic beads to enrich the fecal exfoliated cells. The morphology of the extracted cells was observed by light microscopy through hematoxylin and eosin staining, and the positive rate of fecal occult blood test (FOBT) and the detection rate of colorectal cancer was compared between the two groups. The FOBT-positive rates of natural feces and intestinal cleansing liquid in the control group were 74.00% and 90.00%, respectively, and the FOBT-positive rates of natural feces and intestinal cleansing liquid in the experimental group were 76.00% and 92.00%, respectively. The positive FOBT rate was high, and the difference was statistically significant (P = 0.037 and P = 0.029). The sensitivities of natural fecal exfoliation cytology in the control and experimental groups were 82.00% and 92.00%, respectively. The sensitivity of the experimental group was higher than that of the control group, and the difference was not statistically significant (P = 0.137). The sensitivities of the exfoliated cytology examination of the intestinal cleansing liquid in the control and experimental groups were 88.00% and 98.00%, respectively. The sensitivity of the experimental group was significantly higher than that of the control group, and the difference was statistically significant (P = 0.050). Cell smear results show that the exfoliated cells collected by the three-layer integrated sieve method are unevenly distributed, with overlapping cells and a large number of impurities blurring the background, seriously affecting the observation of cell morphology. The cell structure is blurred, stained unevenly, and arranged in a disorderly manner. The exfoliated cells collected by the nanofolic acid magnetic bead enrichment method are relatively evenly distributed, with no overlapping of cells in patches. The background is clear, and the morphology of each cell can be clearly observed. The cell structure is relatively clear, stained evenly, and distributed evenly. In the cytological examination of fecal exfoliation of colorectal cancer, the nano-Fe3O4 folic acid magnetic bead enrichment method can enrich more target cells compared with the traditional three-layer integrated screen method, improve the detection rate of colorectal cancer, and ensure the exfoliation The cell smears are of higher quality, providing a better sample for clinical assessment of the exfoliated cells. Nano-Fe3O4 folic acid magnetic beads enrichment method can become a simple, efficient, and relatively safe screening method for colorectal cancer, positively affecting early screening developments and diagnosis of colorectal cancer.

Distance to endoscopy services amplifies racial inequities in colorectal cancer mortality in Washington state

BackgroundThis study evaluates relationships among race, access to endoscopy services, and colorectal cancer (CRC) mortality in Washington state (WA). MethodsWe overlayed the locations of ambulatory endoscopy services with place of residence at time of death, using Department of Health data (2011–2018). We compared CRC mortality data within and outside a 10 ​km buffer from services. We used linear regression to assess the impact of distance and race on age at death while adjusting for gender and education level. ResultsAge at death: median 72.9y vs. 68.2y for white vs. non-white (p ​< ​0.001). The adjusted model showed that non-whites residing outside the buffer died 6.9y younger on average (p ​< ​0.001). Non-whites residing inside the buffer died 5.2y younger on average (p ​< ​0.001), and whites residing outside the buffer died 1.6y younger (p ​< ​0.001). We used heatmaps to geolocate death density. ConclusionsResults suggest that geographic access to endoscopy services disproportionately impacts non-whites in Washington. These data help identify communities which may benefit from improved access to alternative colorectal cancer screening methods.

Comparative Effectiveness and Cost-Effectiveness of Colorectal Cancer Screening With Blood-Based Biomarkers (Liquid Biopsy) vs Fecal Tests or Colonoscopy

Colorectal cancer (CRC) screening is highly effective but underused. Blood-based biomarkers (liquid biopsy) could improve screening participation. Using our established Markov model, screening every 3 years with a blood-based test that meets minimum Centers for Medicare & Medicaid Services' thresholds (CMSmin) (CRC sensitivity 74%, specificity 90%) was compared with established alternatives. Test attributes were varied in sensitivity analyses. CMSmin reduced CRC incidence by 40% and CRC mortality by 52% vs no screening. These reductions were less profound than the 68%-79% and 73%-81%, respectively, achieved with multi-target stool DNA (Cologuard; Exact Sciences) every 3 years, annual fecal immunochemical testing (FIT), or colonoscopy every 10 years. Assuming the same cost as multi-target stool DNA, CMSmin cost $28,500/quality-adjusted life-year gained vs no screening, but FIT, colonoscopy, and multi-target stool DNA were less costly and more effective. CMSmin would match FIT's clinical outcomes if it achieved 1.4- to 1.8-fold FIT's participation rate. Advanced precancerous lesion (APL) sensitivity was a key determinant of a test's effectiveness. A paradigm-changing blood-based test (sensitivity >90% for CRC and 80% for APL; 90% specificity; cost ≤$120-$140) would be cost-effective vs FIT at comparable participation. CMSmin could contribute to CRC control by achieving screening in those who will not use established methods. Substituting blood-based testing for established effective CRC screening methods will require higher CRC and APL sensitivities that deliver programmatic benefits matching those of FIT. High APL sensitivity, which can result in CRC prevention, should be a top priority for screening test developers. APL detection should not be penalized by a definition of test specificity that focuses on CRC only.

Abstract 2439: Potential target genes for early stage detection in Hispanic colorectal cancer

Abstract Background: Colorectal Cancer (CRC) has become the second leading cause of death related to cancer worldwide and the third most common malignancy. CRC tumors are classified into stages to describe the cancer; early (stages I and II) and advanced (stages III and IV). Despite the available screening methods and the scientific efforts in the development of a universal biomarker panel for CRC early detection, there still exists a gap in a reliable non-invasive screening method for the Hispanic community. We aimed to elucidate the most important pathways along with the differential gene expression in early and advanced CRC stages in a Hispanic population. Methods: We examined restrospectively 7 tissue samples from a Puerto Rican Hispanic population recruited throughout the Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR) IRB #A2210207. We evaluated transcriptomic changes in advance tumors (n=4) vs. early tumors (n=3) with their respective normal mucosal tissue as negative control. Extracted RNA was sequenced using the Illumina NextSeq (2 × 75bp). The higher-quality reads were aligned, annotated, and quantified to the human genome (hg38) using STAR and RSEM softwares. Gene expression analysis was performed in R statistical software (packages tximport and DESeq2). We compared significantly expressed genes (adjusted p-value &amp;lt;0.05) between study groups (Tumor Advance [TA] vs. Mucosal Advance [MA] and Tumor Early [TE] vs. Mucosal Early [ME]) using Venny, and we performed enrichment analyses and protein-protein interaction networks using Metascape and STRING database, respectively. Results: There were 2284 differentially expressed genes (TA vs. MA) and 984 (TE vs. ME), in which 1736 were unique to advance stages, 436 were unique to early stages and 548 were shared in both tumor stages. Significantly impacted biological processes and pathways include: granulocyte chemotaxis, regulation of inflammatory response, positive regulation of apoptotic process, tissue morphogenesis, G alpha signaling events, interleukin-10 signaling, signaling by interleukins. Additionally, physical and functional interaction networks showed 11 major clusters (≥ 5 genes), which contained several gene hubs including LYN (proto-oncogene), IL-1β, IL-1α, TNF, CCL3, CCL4, CXCR1 and CXCR2 (cytokines/chemokines) among others genes previously reported as CRC biomarkers (DKK1, AQP8, AQP9, CTNNB1, and GNAQ). Discussion/Conclusions: Differential analysis of early CRC tumor samples shows a deregulation of genes related to the inflammatory response which plays an important role in CRC. Modulation of these genes suggests significant potential targets for early detection of CRC in a Hispanic population. Future studies will be focus on the evaluation of selected target genes as a non-invasive early CRC screening method. Citation Format: Elba V. Caraballo, Camille Zenón-Meléndez, Josué Pérez-Santiago, Marcia Cruz-Correa. Potential target genes for early stage detection in Hispanic colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2439.

Detection of Upper Gastrointestinal Disorders in Patients with Positive Fecal Immunochemical Test (FIT) and Normal Colonoscopy: A Cross-Sectional Study

Abstract Introduction Colorectal cancer (CRC) is the second most prevalent cancer in the world, and the fecal immunochemical test (FIT) can be mentioned among the CRC screening methods based on the detection of occult blood in the feces, which may indicate upper gastrointestinal (UGI) malignancies; therefore, patients with a positive FIT but normal colonoscopy may be considered for a UGI endoscopy. Materials and Methods The present study was conducted on patients with a positive FIT who were submitted to colonoscopy with normal results. They subsequently underwent endoscopy for the detection of UGI disorders. Results We included 121 patients (64.5% of women and 35.5% of men; average age: 58.85 ± 12.93 years), 72.7% of whom were positive for Helicobacter pylori. The predominant result of the UGI endoscopy was normal, followed by erythema of the gastric mucosa, and anemia and dyspepsia were the most common clinical findings. The most common pathological result was chronic gastritis, followed by acute gastritis. Only one patient presented stomach cancer (adenocarcinoma). Conclusion Considering the small prevalence of cancer in the UGI endoscopies of patients with positive FIT and normal colonoscopy, to the performance of UGI endoscopy in these patients may not be necessary.

Questionnaire as a stratification method in organizing colorectal cancer screening

The purpose of the study: to compare the efficacy of questionnaires and fecal immunochemical tests in stratification of risk groups during colorectal cancer screening. A non-randomized comparative study was conducted to evaluate the effectiveness of two stratification methods for colorectal cancer screening as part of pilot projects in the regions of the Central Federal District of the Russian Federation. In the first group, the stratification method was the original questionnaire, and in the second group — the fecal immunochemical test (FIT). All participants included in the first and second groups underwent colonoscopy at the second stage of screening. A total of 250 respondents participated in the study, 128 in the questionnaire group and 122 in the FIT group. In the questionnaire group, a high risk of colorectal cancer was found in 91 (71.1 %) individuals, while 37 (28.9 %) respondents had a low risk. Based on colonoscopy results, colorectal cancer and colorectal polyps were diagnosed in 65 (50.8 %) participants, and no significant pathology was found in 63 (49.2 %). In the FIT group, 102 (83.6 %) participants tested positive (FIT+) and 20 (16.4 %) tested negative (FIT-). According to the results of the performed colonoscopy, colorectal cancer and colon polyps were diagnosed in 75 (61.5 %) individuals, while no significant pathology was detected in 47 (38.5 %) participants. The sensitivity of the questionnaire was 86.2 % (95 % CI 75.3–93.5 %) and specificity was 44.4 % (95 % CI 31.9–57.5 %); the predictive value of a positive result was 61.5 % (95 % CI 50.7–71.6 %), and the predictive value of a negative result was 75.7 % (95 % CI 58.8–88.2 %). The FIT sensitivity was 86.7 % (95 % CI 76.8–93.4 %), the specificity was 21.3 % (95 % CI 10.7–35.7 %), the predictive value of a positive result was 63.7 % (95 % CI 53.6–73.0 %), and the predictive value of a negative result was 50.0 % (95 % CI 27.2–72.8 %). In conclusion, the questionnaire method in the colorectal cancer screening model is comparable in sensitivity and specificity to those of the FIT. It is essential to emphasize that questionnaires, along with ease of implementation, do not entail significant economic costs.

A107 ANALYSIS OF THE EFFICACY IN TRANSITIONING FROM FOBT TO FIT FOR COLORECTAL CANCER SCREENING AT A SINGLE CENTRE IN ONTARIO

Abstract Background Colonoscopy is the gold standard for detecting colorectal cancer (CRC) and advanced lesions, but is an invasive and carries some risks, with limited availability and accessibility. Alternatively, the fecal occult blood test (FOBT) and fecal immunochemical test (FIT) are both non-invasive, cost-effective screening tests that can also be used to detect CRC, advanced lesions, and polyps, identifying individuals to be prioritized to undergo colonoscopy. FOBT screens for small amounts of blood in stool by detecting heme through a chemical reaction. FIT confirms the presence of blood in stool by using antibodies to detect hemoglobin. Prior to 2019, Ontario employed FOBT as the preferred method for CRC screening in eligible individuals. In early 2019, Ontario transitioned to FIT as the preferred screening test, due its established superior test performance for identifying patients with high risk lesions for colon cancer. Aims This single-centre retrospective study analyzed the change in efficacy of detecting advanced lesions, when transitioning from FOBT to FIT, as identified on subsequent colonoscopy Methods A retrospective chart review was conducted of approximately 1000 patients undergoing colonoscopy for FOBT or FIT at Cambridge Memorial Hospital, covering the period of transition from FOBT to FIT. Colonoscopies were performed by 10 endoscopists. Patients were stratified into 2 groups based on fecal test type, FOBT (N = 344) and FIT (N = 572). Overall and individual proportions of cancer, polyps, adenomas, advanced adenomas (AA), and sessile serrated adenomas (SSA) detection in the subsequent colonoscopies were calculated for both groups. The efficacy of both tests was then assessed using statistical analysis. Results In total, 344 patients were included for FOBT analysis and results included: cancer (5.52%), any polyp (56.69%), adenoma (43.6%), AA (20.64), and SSA (6.1%). In contrast, 572 patients were included for analysis of FIT group and results included: cancer (3.85%), any polyp (83.22%), adenoma (76.92%), AA (43.01), and SSA (12.94%). Cancer detection was similar in the 2 groups. There was significant improvement in polyp, adenoma, advanced adenoma, and sessile serrated adenoma detection with FIT compared to FOBT. This improvement was consistent in all endoscopists, but more pronounced in endoscopists with lower detection rates in FOBT cases. Conclusions The use of FIT as a screening stool test, as compared to FOBT, was associated with a significantly improved detection for polyps, adenomas, AA, and SSA, confirming greater accuracy and sensitivity of FIT as a screening tool. This result confirms the premise, at least at a single institution, that by switching to FIT, Ontario has improved colon cancer screening and prevention with more efficient and higher yield utilization of a limited and costly health care resource Funding Agencies None

Development and validation of the PERCEPT-PREVENT tool to determine risk perception and attitudes towards digestive cancer screening.

Colorectal cancer (CRC) screening is recommended worldwide, while gastric cancer (GC) screening may also be defendable in some settings. However, adherence rates and factors influencing participation are not well characterized. This study aimed to validate a tool to determine risk perception of CRC and GC and also of endoscopy-related complications. A questionnaire in CRC risk perception based on the Health Belief Model was used. Forward/backward translation (English-Portuguese) and cultural adaptation were performed. After revision by a panel of experts, the questionnaire was adapted to target GC risk perception and perceptions towards endoscopy-related complications. The final version of the questionnaire (PERCEPT-PREVENT tool) was applied to 44 individuals, through telephonic interview, at enrolment and at intervals ≤3 weeks. Test-retest reliability and agreement were assessed. Almost perfect reliability between test and retest was obtained for CRC symptom knowledge score (ICC = 0.88), risk factor knowledge score (ICC = 0.89), and perceived severity (ICC = 0.84). At least moderate agreement between test and retest was obtained for GC symptom knowledge score (ICC = 0.94), risk factor knowledge score (ICC = 0.92), and perceived severity (ICC = 0.58). Test-retest reliability was assessed for barrier domains [faecal occult blood test ICC = 0.63; colonoscopy ICC = 0.79; upper GI endoscopy (UGIE) ICC = 0.83]. A total of 91% and 98% of participants gave the same answer in the test and retest for preferred method of CRC screening and intention to undergo UGIE for GC screening combined with a screening colonoscopy, respectively. PERCEPT-PREVENT is a valid and reliable tool for CRC and GC risk perception evaluation.

Abstract B074: A biobank of fecal immunochemical tests (FIT) to study gut microbiome-mediated cancer disparities

Abstract Introduction: Colorectal cancer (CRC) poses a disproportionate burden among certain Hispanic/Latino subgroups, such as Puerto Rican and Cuban individuals, and Black individuals. Causes of CRC disparities are poorly understood but are likely driven by social determinants of health (SDOH), which may directly and indirectly influence the gut microbiome (GM). In turn, the GM is increasingly implicated in colorectal carcinogenesis. Therefore, it is plausible that the GM may be targeted to reduce excess CRC burden among disproportionately affected populations. However, prior studies of the GM and CRC had limited inclusion of underserved populations and limited collection of SDOH data. Objective: To clearly define the role of the GM in CRC and other cancer disparities, we conducted a pilot study to establish a well-annotated cohort that includes longitudinally collected fecal specimens among diverse populations. Methods: We leveraged fecal immunochemical tests (FIT), a cost-effective method for CRC screening in patient populations with limited access to colonoscopy, in which the GM can be well characterized. Participants completed annual FIT testing following standard protocols as implemented in a Federally Qualified Health Center. FIT samples were processed and banked at Moffitt Cancer Center in -80ºC freezers. All participants completed stool and risk factor questionnaires capturing SDOH, medical history, diet, and lifestyle exposures. To further validate the FIT microbiome, we extracted DNA from 8 sets of triplicate FIT aliquots (200ul each) using the automated MagCore®️ DNA Kit and then performed shotgun sequencing to characterize the fecal microbiome. To test for quality of the data and to compare microbiome metrics (e.g., alpha diversity and microbial abundances) in replicate samples, we calculated intraclass correlation coefficients (ICCs) using linear mixed effects models. Results: In just one clinic, to date, more than N=79 individuals who are primarily Spanish speakers and persons from other racial/ethnic minority subgroups have been enrolled. The racial and ethnic distribution included 39% Mexican, 11% Black, 6% Puerto Rican, 9% Central or South American, and 5% Cuban individuals. Approximately, 59% of the consented population preferentially spoke Spanish and 14% tested positive on the FIT. In the pilot FIT testing samples, we found that the integrity of the DNA was high, with only a few (N=3 of 24) samples with insufficient DNA yield for shotgun metagenomic sequencing. ICCs were generally above ≥ 95% for alpha diversity metrics and abundance of species/genes indicating excellent handling and processing procedures for FIT microbiome extraction and sequencing. Conclusion: Our findings support the concept that FIT-based community screening programs offer exceptional opportunity for GM research in diverse, underrepresented populations. Our future studies will integrate the SDOH data and expand this cohort with the goal of contributing novel insights regarding associations of the GM with early pathogenesis of CRC across diverse populations. Citation Format: Doratha Byrd, Stephanie Hogue, Xuefeng Wang, Sugriva Forsyth, Martha Fuentes, Kathleen Egan, Tiffany Carson, Youngchul Kim, Jessica Islam, Cathy Meade, Clement Gwede. A biobank of fecal immunochemical tests (FIT) to study gut microbiome-mediated cancer disparities [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr B074.

Endoscopic treatment of colorectal polyps and early colorectal cancer

Background: Colonoscopy offers higher diagnostic sensitivity than other colorectal cancer screening methods and provides the advantage of both diagnostic tissue sampling and polyp removal. Since the majority of colorectal cancers evolve from adenomatous polyps, polyp resection through colonoscopy is widely considered an effective method of preventing colorectal cancer and reducing mortality rates.Current Concepts: Determining colorectal polyp size and shape requires comprehensive endoscopy with enhanced imaging techniques to choose treatment directions and the appropriate colorectal polypectomy method. The selection of the polypectomy method is contingent upon the polyp’s attributes and possible malignancy according to US Multi-Society Task Force on Colorectal Cancer and European gastrointestinal endoscopy guidelines. This article examines eight polypectomy procedures: cold forceps polypectomy, hot biopsy polypectomy, cold snare polypectomy, hot snare polypectomy, endoscopic mucosal resection (EMR), and modified EMR techniques. Each method has unique benefits and is suitable for particular polyp types and sizes. Piecemeal EMR and endoscopic submucosal dissection offer alternatives for larger or challenging lesions that require careful planning and follow-up. After endoscopic resection of early colorectal cancer, further surgery may be necessary depending on the risk of lymph node metastasis as determined by specific histologic findings following Korean and Japanese guidelines.Discussion and Conclusion: The choice of endoscopic resection technique, which depends on factors such as polyp shape, size, and location as well as endoscopist skill, is crucial for ensuring complete polyp removal.

ANALYSIS OF THE TRACKING INITIATIVES OF COLORECTAL CANCER IN BRAZIL.

Colorectal cancer (CRC) is an important public health problem, as it represents the world's third most diagnosed neoplasm and the fourth cause of mortality. Its prevention can be divided into primary, secondary, demonstrated by tracking techniques, and tertiary, which consists of cancer diagnosis in symptomatic patients. Despite presenting a high incidence, the mortality rates decreased in the past two decades in developed countries, while the opposite happened in underdeveloped countries. That is attributed to the increase of colorectal cancer tracking programs in developed countries, which allows the precocious diagnosis and treatment of precancerous injuries and CRC. In that manner, the American Cancer Society divides the secondary tracking methods in exams based on feces samples and visual analysis of the colon and rectum, indicating its initiation starting at 45 years old in lower-risk patients. Verify in an analytical way the actions of colorectal cancer tracking held in Brazil, as to evaluate the necessity of implementation of a national tracking program of CRC. The methodology was based on a descriptive-quantitative secondary study that correlated the incidence of CRC, its morbidity and mortality, and the impact of the precocious tracking programs. It included activities not reported in medical literature through personal contacts with coordinators of regional programs to compare with the existent data in the literature. It was used as a variable for the tracking strategies the exams held, and their respective results. It described nine programs held in different regions in Brazil, using two screening methods for CRC: a noninvasive method that consists of the research of blood hidden in feces, being the majority through the FIT method, and an invasive method, having the colonoscopy as its representant. These initiatives were effective in the detection of early forms of this disease. Despite the existence of several private tracking programs and the broad divulgation of the importance of the tracking and the early diagnosis of colorectal cancer, it was demonstrated that Brazil lacks a national program that patronizes the tracking methods, which reflects in the major prevalence of late diagnosis in the population.

Racial/ethnic disparities in colorectal cancer screening methods: Unveiling patterns and implications.

124 Background: Colorectal cancer screening (CRC) is crucial for reducing morbidity and mortality of CRC. The type of screening method chosen is important for accessibility, compliance, and effectiveness. Colonoscopy and sigmoidoscopy are considered the gold standard while fecal occult blood tests (FOBT) are non-invasive, inexpensive, and more available. Our study examined the racial/ethnic disparities associated with various CRC screening methods. Methods: We utilized the cross-sectional nationally representative data from the 2018-2021 Behavioral Risk Factor Surveillance System (BRFSS). The sample included individuals between 50-75 years, the recommended age for CRC screening. Logistic regression analysis was performed to investigate up-to-date CRC screening rates and the choice of CRC screening method in related to race/ethnicity, after controlling for confounding factors. Results: Among the weighted population of 119,841,048 individuals aged 50-75 years, 44.6% reported having an up-to-date colonoscopy/sigmoidoscopy only, 5.0% had only FOBT in the past year, and 5.8% had both tests. The logistic regression models revealed that Asians and Pacific Islanders (APIs; adjusted odds ratio [aOR]: 0.59; 95%CI: 0.49-0.69), American Indians and Alaska Natives (AIs/ANs; aOR: 0.73; 95%CI: 0.59-0.90), and Hispanic individuals (aOR: 0.76; 95%CI: 0.69-0.84) were less likely to undergo colonoscopy/sigmoidoscopy only compared to non-Hispanic White (NHW) peers. Conversely, APIs (aOR: 1.46; 95%CI: 0.98-2.17) and Hispanic individuals (aOR: 1.46; 95%CI: 1.20-1.79) were associated with a higher rate of recent FOBT only compared to their NHW individuals. Regarding the combination of up-to-date colonoscopy/sigmoidoscopy and FOBT, non-Hispanic Blacks (NHB; aOR: 1.66; 95%CI: 1.44-1.92) and Hispanic individuals (aOR: 1.61; 95CI: 1.33-1.95) were more likely to have both tests compared to NHW individuals. Conclusions: Our findings highlight the significant variations in CRC screening preferences among different racial/ethnic groups, which are likely influenced by cultural backgrounds, health literacy and access, and language barriers. It is crucial for healthcare providers to acknowledge these differences, as they can significantly impact patient engagement and compliance with CRC screening recommendations. Emphasizing culturally informed approaches to CRC screening is essential for fostering trust, promoting equitable healthcare, and ultimately reducing disparities in CRC outcomes.