An efficient strategy for evaluating new non-invasive screening tests for colorectal cancer: the guiding principles.

OBJECTIVE: New screening tests for colorectal cancer (CRC) are rapidly emerging. Conducting trials with mortality reduction as the end point supporting their adoption is challenging. We re-examined the principles underlying evaluation of new non-invasive tests in view of technological developments and identification of new biomarkers. DESIGN: A formal consensus approach involving a multidisciplinary expert panel revised eight previously established principles. RESULTS: Twelve newly stated principles emerged. Effectiveness of a new test can be evaluated by comparison with a proven comparator non-invasive test. The faecal immunochemical test is now considered the appropriate comparator, while colonoscopy remains the diagnostic standard. For a new test to be able to meet differing screening goals and regulatory requirements, flexibility to adjust its positivity threshold is desirable. A rigorous and efficient four-phased approach is proposed, commencing with small studies assessing the test's ability to discriminate between CRC and non-cancer states (phase I), followed by prospective estimation of accuracy across the continuum of neoplastic lesions in neoplasia-enriched populations (phase II). If these show promise, a provisional test positivity threshold is set before evaluation in typical screening populations. Phase III prospective studies determine single round intention-to-screen programme outcomes and confirm the test positivity threshold. Phase IV studies involve evaluation over repeated screening rounds with monitoring for missed lesions. Phases III and IV findings will provide the real-world data required to model test impact on CRC mortality and incidence. CONCLUSION: New non-invasive tests can be efficiently evaluated by a rigorous phased comparative approach, generating data from unbiased populations that inform predictions of their health impact.

Impact of Cold Snare vs Cold Forceps Resection of Diminutive Adenomas on Segmental Incomplete Resection Rate.

INTRODUCTION: Polypectomy technique, for diminutive lesion resection, is variable among colonoscopists using either cold snare polypectomy (CSP) or cold forceps polypectomy (CFP). While it is well described that CSP is a preferred technique to resect small lesions, there is little data evaluating the impact resection techniques have on metachronous adenoma burden. The aim of this study was to evaluate the rate of incomplete resection attributable to CSP and CFP of diminutive adenomas. METHODS: This is a 2-center retrospective cohort study evaluating the segmental incomplete resection rate (S-IRR) of diminutive tubular adenomas (TA). S-IRR was calculated by subtracting the segmental metachronous adenoma rate in a specific colonic segment without adenoma from segments with adenoma on index colonoscopy. The primary outcome was the S-IRR of diminutive TA resected by CSP or CFP on index colonoscopy. RESULTS: A total of 1,504 patients were included in the analysis: 1,235 with TA <6 mm and 269 with TA 6-9 mm as the most advanced lesion. The S-IRR in a segment that had a <6-mm TA incompletely resected by CFP on index colonoscopy was 13%. The S-IRR in a segment that had a <6-mm TA incompletely resected by CSP was 0%. Among 12 included colonoscopists, the range of overall S-IRR was 1.1%-24.4% with an average S-IRR of 10.3%. DISCUSSION: S-IRR was 13% higher with CFP resection of diminutive TA than with CSP. A proposed S-IRR metric of <5% is a target goal for all diminutive polyp resection because 3/12 colonoscopists achieved this low rate. S-IRR can be used as a methodology to compare and quantify the difference in segmental metachronous adenoma burden across various polypectomy removal methods.

DNA methylation and miRNA expression in colon adenomas compared with matched normal colon mucosa and carcinomas.

Dysregulation of DNA methylation patterns and non-coding RNA, including miRNAs, has been implicated in colon cancer, and these changes may occur early in the development of carcinoma. In this study, the role of epigenetics as early changes in colon tumorigenesis was examined through paired sample analysis of patient-matched normal, adenoma and carcinoma samples. Global methylation was assessed by genomic 5-methyl cytosine (5-mC) and long interspersed nuclear element-1 (LINE-1) promoter methylation by pyrosequencing. KRAS mutations were also assessed by pyrosequencing. Expression of miRNA, specifically, two microRNA genes-miR-200a and let-7c-was analysed using RT-qPCR. Differences in global methylation in adenomas were not observed, compared with normal tissue. However, LINE-1 methylation was decreased in adenomas (p = .056) and carcinomas (p = .011) compared with normal tissue. Expressions of miRNA, miR-200a and let-7c were significantly higher in adenomas than normal tissues (p = .008 and p = .045 respectively). Thus the significant changes in LINE-1 methylation and microRNA expression in precancerous lesions support an early role for epigenetic changes in the carcinogenic process. Epigenetic characteristics in adenomas may provide potential diagnostic and prognostic therapeutic targets early in cancer development at the adenoma stage.

Risk of total metachronous advanced neoplasia in patients with both small tubular adenomas and serrated polyps.

BACKGROUND AND AIMS: The impact of concomitant small serrated polyps (SPs) on the risk of subsequent neoplasia when small tubular adenomas (TAs) are found is uncertain. METHODS: Patients who on index colonoscopy had ≤2 TAs of <10 mm in size in isolation were compared with those with concomitant ≤2 small-sized SPs. SP was inclusive of polyps described by pathology as sessile serrated lesions (SSLs) or proximal hyperplastic polyps (HPs) <10 mm in size. The primary endpoint was the rate of total metachronous advanced neoplasia (T-MAN) compared among the TAs in the isolation group and the groups inclusive of SPs (SSLs or proximal HPs). RESULTS: For patients with TAs and small SPs found concomitantly, the rate of T-MAN was 9.6% (24/251), which was significantly higher than the rate of T-MAN in patients with isolated small TAs (5.2% [59/1138], P = .011). Within the concomitant SP cohort, the rate of T-MAN in the proximal HP subgroup remained significantly increased (9% [19/212]) compared with the isolated small TA group (P = .037). CONCLUSIONS: When small TAs are found concomitantly with small SPs, there is an increase in the rate of T-MAN in comparison with isolated TAs. This increase in T-MAN also occurs when small TAs are found in conjunction with small proximal HPs. The presence of concomitant small SPs should be considered in determining surveillance intervals when small TAs are identified in colonoscopy screening programs.

Metachronous Advanced Neoplasia on Surveillance Colonoscopy in Patients With Young- vs Older-onset of Colorectal Cancer.

The incidence of colorectal cancer (CRC) and cancer-related mortality has increased in patients <55 years old.1 Consensus on optimal intervals for post-CRC surveillance colonoscopy in young patients is lacking. The primary endpoint of this study was comparison of rates of metachronous advanced neoplasia (AN) in patients diagnosed with CRC at <50 and 50-75 years. The secondary aim was to evaluate risk factors of metachronous AN.

Segmental metachronous adenoma rate as a metric for monitoring incomplete resection in a colonoscopy screening program.

BACKGROUND AND AIMS: Polypectomy technique has been shown to vary among colonoscopists, and interval colorectal cancer may result from incomplete resection of an adenoma. Methods to monitor polypectomy quality and the size of polyps resected to monitor have not been well defined. The aim of this study was to compare the rate of metachronous adenoma attributable to incomplete resection in polyps 6 to 9 mm versus polyps 10 to 20 mm. METHODS: The segmental metachronous adenoma rate attributable to incomplete resection (SMAR-IR) was calculated by subtracting the rate of metachronous neoplasia (MN) in segments without adenoma from segments with adenoma. The primary outcome of the study was the SMAR-IR in polyps 6 to 9 mm and 10 to 20 mm found on index colonoscopy. RESULTS: Of 337 patients included in the analysis, 146 patients had a tubular adenoma (TA) 10 to 20 mm in size and 191 patients a TA 6 to 9 mm in size as the most advanced lesion. For cases in which an index 10- to 20-mm TA was resected, the SMAR in segments with adenoma was 21.0% and in segments without adenoma 9.6%, so the SMAR-IR was 11.4% (95% confidence interval, 4.5-18.3). For cases in which an index 6- to 9-mm TA was resected, the SMAR in segments with adenoma was 22.0% and in segments without adenoma 8.8%, so the SMAR-IR was 13.2% (95% confidence interval, 7.2-19.4). Among 6 colonoscopists, the SMAR-IR ranged between 7.0% and 15.5% for polyps 6 to 20 mm. CONCLUSIONS: MN rates in segments with a TA 10-20 mm and a TA 6-9 mm are higher than the MN rates in segments without index neoplasia. Incomplete resection of neoplasia appears to be a significant risk factor for MN in 6- to 9-mm lesions as well as larger ones.

Devices and techniques for flexible endoscopic management of Zenker's diverticulum (with videos).

BACKGROUND AND AIMS: Zenker's diverticulum (ZD) has traditionally been treated with open surgery or rigid endoscopy. With the advances in endoscopy, alternative flexible endoscopic treatments have been developed. METHODS: This document reviews current endoscopic techniques and devices used to treat ZD. RESULTS: The endoscopic techniques may be categorized as the traditional flexible endoscopic septal division and the more recent submucosal tunneling endoscopic septum division, also known as peroral endoscopic myotomy for ZD. This document also addresses clinical outcomes, safety, and financial considerations. CONCLUSIONS: Flexible endoscopic approaches treat symptomatic ZD with results that are favorable compared with traditional open surgical or rigid endoscopic alternatives.

Enhanced EUS imaging (with videos).

BACKGROUND AND AIMS: EUS remains a primary diagnostic tool for the evaluation of pancreaticobiliary disease. Although EUS combined with FNA or biopsy sampling is highly sensitive for the diagnosis of neoplasia within the pancreaticobiliary tract, limitations exist in specific clinical settings such as chronic pancreatitis. Enhanced EUS imaging technologies aim to aid in the detection and diagnosis of lesions that are commonly evaluated with EUS. METHODS: We reviewed technologies and methods for enhanced imaging during EUS and applications of these methods. Available data regarding efficacy, safety, and financial considerations are summarized. RESULTS: Enhanced EUS imaging methods include elastography and contrast-enhanced EUS (CE-EUS). Both technologies have been best studied in the setting of pancreatic mass lesions. Robust data indicate that neither technology has adequate specificity to serve as a stand-alone test for pancreatic malignancy. However, there may be a role for improving the targeting of sampling and in the evaluation of peritumoral lymph nodes, inflammatory pancreatic masses, and masses with nondiagnostic FNA or fine-needle biopsy sampling. Further, novel applications of these technologies have been reported in the evaluation of liver fibrosis, pancreatic cysts, and angiogenesis within neoplastic lesions. CONCLUSIONS: Elastography and CE-EUS may improve the real-time evaluation of intra- and extraluminal lesions as an adjunct to standard B-mode and Doppler imaging. They are not a replacement for EUS-guided tissue sampling but provide adjunctive diagnostic information in specific clinical situations. The optimal clinical use of these technologies continues to be a focus of ongoing research.

Interobserver reliability of methods to determine complete resection of adenomas in colonoscopy.

BACKGROUND: Forceps margin biopsy and polypectomy specimen margins have both been used to assess for polypectomy resection adequacy. The interobserver reliability of the two methods has not been well described. METHODS: The interpretability of polypectomy specimens for presence of residual neoplasia at the margin was assessed by two blinded pathologists. Next, the concordance of forceps margin biopsy interpretations between three blinded pathologists was evaluated by calculation of interobserver κ. RESULTS: Rates of polypectomy specimen margin interpretability were low: 24/92 (26 %) for pathologist A, 28/92 (30.4 %) for pathologist B. Concordance of forceps margin biopsy interpretations (n = 129) between pathologists was high. Two internal pathologists showed substantial agreement in margin biopsy interpretations (κ 0.779; 95 %CL 0.543, 0.912). The concordance remained strong after biopsies were reviewed by a third, external pathologist (κ 0.829; 95 %CL 0.658, 0.924). There was complete agreement on 123/129 (95.3 %) between all three pathologists for presence of neoplasia. CONCLUSION: The majority of polypectomy specimen margins were uninterpretable by pathologists for presence of residual neoplasia. Forceps margin biopsy shows strong interobserver reliability in adenomatous lesions.

AGA White Paper: Roadmap for the Future of Colorectal Cancer Screening in the United States.

The American Gastroenterological Association's Center for Gastrointestinal Innovation and Technology convened a consensus conference in December 2018, entitled, "Colorectal Cancer Screening and Surveillance: Role of Emerging Technology and Innovation to Improve Outcomes." The goal of the conference, which attracted more than 60 experts in screening and related disciplines, including the authors, was to envision a future in which colorectal cancer (CRC) screening and surveillance are optimized, and to identify barriers to achieving that future. This White Paper originates from that meeting and delineates the priorities and steps needed to improve CRC outcomes, with the goal of minimizing CRC morbidity and mortality. A one-size-fits-all approach to CRC screening has not and is unlikely to result in increased screening uptake or desired outcomes owing to barriers stemming from behavioral, cultural, and socioeconomic causes, especially when combined with inefficiencies in deployment of screening technologies. Overcoming these barriers will require the following: efficient utilization of multiple screening modalities to achieve increased uptake; continued development of noninvasive screening tests, with iterative reassessments of how best to integrate new technologies; and improved personal risk assessment to better risk-stratify patients for appropriate screening testing paradigms.

Diminutive Polyps With Advanced Histologic Features Do Not Increase Risk for Metachronous Advanced Colon Neoplasia.

BACKGROUND & AIMS: With advances in endoscopic imaging, it is possible to differentiate adenomatous from hyperplastic diminutive (1-5 mm) polyps during endoscopy. With the optical Resect-and-Discard strategy, these polyps are then removed and discarded without histopathology assessment. However, failure to recognize adenomas (vs hyperplastic polyps), or discarding a polyp with advanced histologic features, could result in a patient being considered at low risk for metachronous advanced neoplasia, resulting in an inappropriately long surveillance interval. We collected data from international cohorts of patients undergoing colonoscopy to determine what proportion of patients are high risk because of diminutive polyps advanced histologic features and their risk for metachronous advanced neoplasia. METHODS: We collected data from 12 cohorts (in the United States or Europe) of patients undergoing colonoscopy after a positive result from a fecal immunochemical test (FIT cohort, n = 34,221) or undergoing colonoscopies for screening, surveillance, or evaluation of symptoms (colonoscopy cohort, n = 30,123). Patients at high risk for metachronous advanced neoplasia were defined as patients with polyps that had advanced histologic features (cancer, high-grade dysplasia, ≥25% villous features), 3 or more diminutive or small (6-9 mm) nonadvanced adenomas, or an adenoma or sessile serrated lesion ≥10 mm. Using an inverse variance random effects model, we calculated the proportion of diminutive polyps with advanced histologic features; the proportion of patients classified as high risk because their diminutive polyps had advanced histologic features; and the risk of these patients for metachronous advanced neoplasia. RESULTS: In 51,510 diminutive polyps, advanced histologic features were observed in 7.1% of polyps from the FIT cohort and 1.5% polyps from the colonoscopy cohort (P = .044); however, this difference in prevalence did not produce a significant difference in the proportions of patients assigned to high-risk status (0.8% of patients in the FIT cohort and 0.4% of patients in the colonoscopy cohort) (P = .25). The proportions of high-risk patients because of diminutive polyps with advanced histologic features who were found to have metachronous advanced neoplasia (17.6%) did not differ significantly from the proportion of low-risk patients with metachronous advanced neoplasia (14.6%) (relative risk for high-risk categorization, 1.13; 95% confidence interval 0.79-1.61). CONCLUSION: In a pooled analysis of data from 12 international cohorts of patients undergoing colonoscopy for screening, surveillance, or evaluation of symptoms, we found that diminutive polyps with advanced histologic features do not increase risk for metachronous advanced neoplasia.

Techniques and devices for the endoscopic treatment of gastroparesis (with video).

BACKGROUND AND AIMS: Gastroparesis is a symptomatic chronic disorder of the stomach characterized by delayed gastric emptying in the absence of mechanical obstruction. Several endoscopic treatment modalities have been described that aim to improve gastric emptying and/or symptoms associated with gastroparesis refractory to dietary and pharmacologic management. METHODS: In this report we review devices and techniques for endoscopic treatment of gastroparesis, the evidence regarding their efficacy and safety, and the financial considerations for their use. RESULTS: Endoscopic modalities for treatment of gastroparesis can be broadly categorized into pyloric, nonpyloric, and nutritional therapies. Pyloric therapies such as botulinum toxin injection, stent placement, pyloroplasty, and pyloromyotomy specifically focus on pylorospasm as a therapeutic target. These interventions aim to reduce the pressure gradient across the pyloric sphincter, with a resultant improvement in gastric emptying. Nonpyloric therapies, such as venting gastrostomy and gastric electrical stimulation, are intended to improve symptoms. Nutritional therapies, such as feeding tube placement, aim to provide nutritional support. CONCLUSIONS: Several endoscopic interventions have shown utility in improving the quality of life and symptoms of select patients with refractory gastroparesis. Methods to identify which patients are best suited for a specific treatment are not well established. Endoscopic pyloromyotomy is a relatively recent development that may prove to be the preferred pyloric-directed intervention, although additional and longer-term outcomes are needed.

Endoscopic devices and techniques for the management of bariatric surgical adverse events (with videos).

BACKGROUND AND AIMS: As the prevalence of obesity continues to rise, increasing numbers of patients undergo bariatric surgery. Management of adverse events of bariatric surgery may be challenging and often requires a multidisciplinary approach. Endoscopic intervention is often the first line of therapy for management of these adverse events. This document reviews technologies and techniques used for endoscopic management of adverse events of bariatric surgery, organized by surgery type. METHODS: The MEDLINE database was searched through May 2018 for articles related to endoscopic management of adverse events of bariatric interventions by using relevant keywords such as adverse events related to "gastric bypass," "sleeve gastrectomy," "laparoscopic adjustable banding," and "vertical banded sleeve gastroplasty," in addition to "endoscopic treatment" and "endoscopic management," among others. Available data regarding efficacy, safety, and financial considerations are summarized. RESULTS: Common adverse events of bariatric surgery include anastomotic ulcers, luminal stenoses, fistulae/leaks, and inadequate initial weight loss or weight regain. Devices used for endoscopic management of bariatric surgical adverse events include balloon dilators (hydrostatic, pneumatic), mechanical closure devices (clips, endoscopic suturing system, endoscopic plication platform), luminal stents (covered esophageal stents, lumen-apposing metal stents, plastic stents), and thermal therapy (argon plasma coagulation, needle-knives), among others. Available data, composed mainly of case series and retrospective cohort studies, support the primary role of endoscopic management. Multiple procedures and techniques are often required to achieve clinical success, and existing management algorithms are evolving. CONCLUSIONS: Endoscopy is a less invasive alternative for management of adverse events of bariatric surgery and for revisional procedures. Endoscopic procedures are frequently performed in the context of multidisciplinary management with bariatric surgeons and interventional radiologists. Treatment algorithms and standards of practice for endoscopic management will continue to be refined as new dedicated technology and data emerge.

Devices and techniques for endoscopic treatment of residual and fibrotic colorectal polyps (with videos).

BACKGROUND AND AIMS: Residual neoplasia after macroscopically complete EMR of large colon polyps has been reported in 10% to 32% of resections. Often, residual polyps at the site of prior polypectomy are fibrotic and nonlifting, making additional resection challenging. METHODS: This document reviews devices and methods for the endoscopic treatment of fibrotic and/or residual polyps. In addition, techniques reported to reduce the incidence of residual neoplasia after endoscopic resection are discussed. RESULTS: Descriptions of technologies and available outcomes data are summarized for argon plasma coagulation ablation, snare-tip coagulation, avulsion techniques, grasp-and-snare technique, EndoRotor endoscopic resection system, endoscopic full-thickness resection device, and salvage endoscopic submucosal dissection. CONCLUSIONS: Several technologies and techniques discussed in this document may aid in the prevention and/or resection of fibrotic and nonlifting polyps.

Endoscopic simulators.

BACKGROUND AND AIMS: Simulation refers to educational tools that allow for repetitive instruction in a nonpatient care environment that is risk-free. In GI endoscopy, simulators include ex vivo animal tissue models, live animal models, mechanical models, and virtual reality (VR) computer simulators. METHODS: After a structured search of the peer-reviewed medical literature, this document reviews commercially available GI endoscopy simulation systems and clinical outcomes of simulation in endoscopy. RESULTS: Mechanical simulators and VR simulators are frequently used early in training, whereas ex vivo and in vivo animal models are more commonly used for advanced endoscopy training. Multiple studies and systematic reviews show that simulation-based training appears to provide novice endoscopists with some advantage over untrained peers with regard to endpoints such as independent procedure completion and performance time, among others. Data also suggest that simulation training may accelerate the acquisition of specific technical skills in colonoscopy and upper endoscopy early in training. However, the available literature suggests that the benefits of simulator training appear to attenuate and cease after a finite period. Further studies are needed to determine if meeting competency metrics using simulation will predict actual clinical competency. CONCLUSIONS: Simulation training is a promising modality that may aid in endoscopic education. However, for widespread incorporation of simulators into gastroenterology training programs to occur, simulators must show a sustained advantage over traditional mentored teaching in a cost-effective manner. Because most studies evaluating simulation have focused on novice learners, the role of simulation training in helping practicing endoscopists gain proficiency using new techniques and devices should be further explored.

Advances in the diagnosis and surveillance of Barrett's esophagus (with videos).

BACKGROUND AND AIMS: Most patients diagnosed with esophageal adenocarcinoma do not carry a known diagnosis of Barrett's esophagus (BE), suggesting that an improved approach to screening may potentially be of benefit. The use of dysplasia as a biomarker and random biopsy protocols for its detection has limitations. In addition, detecting and appropriately classifying dysplasia in patients with known BE can be difficult. METHODS: This document reviews several technologies with a recently established or potential role in the diagnosis and/or surveillance of BE as well as risk stratification for progression to esophageal adenocarcinoma. RESULTS: Two technologies were reviewed for imaging or tissue sampling: (1) wide-area transepithelial sampling and (2) volumetric laser endomicroscopy. Four technologies were reviewed for molecular and biomarker technologies for diagnosis and risk stratification: (1) Cytosponge, (2) mutational load, (3) fluorescence in situ hybridization, and (4) immunohistochemistry. CONCLUSION: Several technologies discussed in this document may improve dysplasia detection in BE in a wide-field manner. Moreover, the addition of different biomarkers may aid in enhanced risk stratification to optimize approaches to surveillance or treatment for patients with BE.

Utilization of Census Tract-Based Neighborhood Poverty Rates to Predict Non-adherence to Screening Colonoscopy.

OBJECTIVES: Efforts to improve colorectal cancer (CRC) screening rates include recognizing predictors of colonoscopy non-adherence and identifying these high-risk patient populations. Past studies have focused on individual-level factors but few have evaluated the influence of neighborhood-level predictors. We sought to assess the effect of census tract-based neighborhood poverty rates on scheduled screening colonoscopy non-adherence. METHODS: In this prospective observational cohort study, data from electronic medical records and appointment tracking software were collected in 599 patients scheduled to undergo outpatient CRC screening colonoscopy at two academic endoscopy centers between January 2011 and December 2012. Non-adherence was defined as failure to attend a colonoscopy appointment within 1 year of the date it was electronically scheduled. Neighborhood poverty rate was determined by matching patients' self-reported home address with their corresponding US census tract. Individual factors including medical comorbidities and prior appointment adherence behavior were also collected. RESULTS: Overall, 17% (65/383) of patients were non-adherent to scheduled colonoscopy at 1-year follow-up. Neighborhood poverty rate was a significant predictor of non-adherence to scheduled screening colonoscopy in multivariate modeling (OR 1.53 per 10% increase in neighborhood poverty rate, 95% CI 1.21-1.95, p < 0.001). By incorporating the neighborhood poverty rate, screening colonoscopy non-adherence was 31% at the highest quartile compared to 14% at the lowest quartile of neighborhood poverty rates (p = 0.006). CONCLUSIONS: Census tract-based neighborhood poverty rates can be used to predict non-adherence to scheduled screening colonoscopy. Targeted efforts to increase CRC screening efficiency and completion among patients living in high-poverty geographic regions could reduce screening disparities and improve utilization of endoscopy unit resources.

Low Referral Rate for Genetic Testing in Racially and Ethnically Diverse Patients Despite Universal Colorectal Cancer Screening.

BACKGROUND & AIMS: Guidelines recommend that all colorectal tumors be assessed for mismatch repair deficiency, which could increase identification of patients with Lynch syndrome. This is of particular importance for minority populations, in whom hereditary syndromes are under diagnosed. We compared rates and outcomes of testing all tumor samples (universal testing) collected from a racially and ethnically diverse population for features of Lynch syndrome. METHODS: We performed a retrospective analysis of colorectal tumors tested from 2012 through 2016 at 4 academic centers. Tumor samples were collected from 767 patients with colorectal cancer (52% non-Hispanic white [NHW], 26% African American, and 17% Hispanic patients). We assessed rates of tumor testing, recommendations for genetic evaluation, rates of attending a genetic evaluation, and performance of germline testing overall and by race/ethnicity. We performed univariate and multivariate regression analyses. RESULTS: Overall, 92% of colorectal tumors were analyzed for mismatch repair deficiency without significant differences among races/ethnicities. However, minority patients were significantly less likely to be referred for genetic evaluation (21.2% for NHW patients vs 16.9% for African American patients and 10.9% for Hispanic patients; P = .02). Rates of genetic testing were also lower among minority patients (10.7% for NHW patients vs 6.0% for AA patients and 3.1% for Hispanic patients; P < .01). On multivariate analysis, African American race, older age, and medical center were independently associated with lack of referral for genetic evaluation and genetic testing. CONCLUSION: In a retrospective analysis, we found that despite similar rates of colorectal tumor analysis, minority patients are less likely to be recommended for genetic evaluation or to undergo germline testing for Lynch syndrome. Improvements in institutional practices in follow up after tumor testing could reduce barriers to diagnosis of Lynch diagnosis in minorities.