Mismatch Repair Deficiency Testing in Patients With Colorectal Cancer and Nonadherence to Testing Guidelines in Young Adults

Creation of a Quality Payment Program Measure for Mismatch Repair or Microsatellite Instability Biomarker Testing Status in Colorectal, Endometrial, Gastroesophageal, or Small Bowel Carcinoma

CONTEXT.—

Quality measures that are supported by evidence-based clinical practice guidelines are preferred for assessing the quality of pathologists' practices. Careful testing of a measure ensures that scores obtained by that measure reflect the quality of a pathologist's practice.

OBJECTIVE.—

To specify a new quality measure and to demonstrate through testing that it is suitable for measuring pathologists' appropriate incorporation of information regarding microsatellite instability (MSI) and/or mismatch repair (MMR) status in pathology reports for colorectal, endometrial, gastroesophageal, and small bowel carcinoma.

DESIGN.—

The College of American Pathologists collaborated with the American Gastroenterological Association to specify and test the new measure. Face validity testing was used to investigate the validity of the measure. Feasibility testing was conducted to understand if data elements required by the measure specification were readily accessible. Signal-to-noise analysis was used to characterize the measure's reliability.

RESULTS.—

Guideline recommendations for MSI and/or MMR testing supported specifications for the measure. Face validity testing indicated that the measure could distinguish the quality of care provided. Data elements required by the measure specification were found to be accessible, which supported the measure's feasibility. Reliability testing showed that differences in measure score were attributable to real differences in performance rather than random variation in scoring.

CONCLUSIONS.—

The Mismatch Repair or Microsatellite Instability Biomarker Testing Status in Colorectal Carcinoma, Endometrial, Gastroesophageal, or Small Bowel Carcinoma measure was appropriately specified, and testing demonstrated that it is well suited for characterizing the quality of pathologists' communication of MMR and/or MSI status.

Precision Medicine in the Era of Genetic Testing: Microsatellite Instability Evolved

The recognized importance of microsatellite instability (MSI) in cancer has evolved considerably in the past 30 years. From its beginnings as a molecular predictor for Lynch syndrome, MSI first transitioned to a universal screening test in all colorectal and endometrial cancers, substantially increasing the identification of patients with Lynch syndrome among cancer patients. More recently, MSI has been shown to be a powerful biomarker of response to immune checkpoint blockade therapy across a diversity of tumor types, and in 2017 was granted Food and Drug Administration approval as the first tumor histology-agnostic biomarker for a cancer therapy. Focusing on colorectal cancer specifically, immune checkpoint blockade therapy has been shown to be highly effective in the treatment of both MSI-high (MSI-H) colon and rectal cancer, with data increasingly suggesting an early role for immune checkpoint blockade therapy in MSI-H colorectal tumors in the neoadjuvant setting, with the potential to avoid more toxic and morbid approaches using traditional chemotherapy, radiation therapy, and surgery. The success of MSI as an immune checkpoint blockade target has inspired ongoing vigorous research to identify new similar targets for immune checkpoint blockade therapy that may help to one day expand the reach of this revolutionary cancer therapy to a wider swath of patients and indications.

Real-world study on microsatellite instability and mismatch repair deficiency testing patterns among patients with metastatic colorectal cancer in Spain

PURPOSE

Clinical practice guidelines recommend that all patients with metastatic colorectal cancer (mCRC) should be tested for mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H). We aimed to describe the dMMR/MSI-H testing practice in patients with mCRC in Spanish centers.

METHODS

Multicenter, observational retrospective study that included patients newly diagnosed with mCRC or who progressed to a metastatic stage from early/localized stages.

RESULTS

Three hundred patients were included in the study from May 2020 through May 2021, with a median age of 68 years, and two hundred twenty-five (75%) had stage IV disease at initial diagnosis; two hundred eighty-four patients received first-line treatment, and dMMR/MSI-H testing was performed in two hundred fifty-one (84%) patients. The results of the dMMR/MSI-H tests were available in 61 (24%) of 251 patients before the diagnosis of metastatic disease and in 191 (81%) of 236 evaluable patients for this outcome before the initiation of first-line treatment. Among the 244 patients who were tested for dMMR/MSI-H with IHC or PCR, 14 (6%) were MMR deficient. The most frequent type of first-line treatment was the combination of chemotherapy and biological agent, that was received by 71% and 50% of patients with MMR proficient and deficient tumors, respectively, followed by chemotherapy alone, received in over 20% of patients in each subgroup. Only 29% of dMMR/MSI-H tumors received first-line immunotherapy.

CONCLUSION

Our study suggests that a high proportion of patients with mCRC are currently tested for dMMR/MSI-H in tertiary hospitals across Spain. However, there is still room for improvement until universal testing is achieved.

TRIAL REGISTRATION

Not applicable.

Report from the 24th Annual Western Canadian Gastrointestinal Cancer Consensus Conference on Colorectal Cancer, Richmond, British Columbia, 28-29, October 2022

The 24th annual Western Canadian Gastrointestinal Cancer Consensus Conference (WCGCCC) was held in Richmond, British Columbia, on 28-29 October 2022. The WCGCCC is an interactive multidisciplinary conference attended by healthcare professionals from across Western Canada (British Columbia, Alberta, Saskatchewan, and Manitoba) who are involved in the care of patients with gastrointestinal cancer. Surgical, medical, and radiation oncologists; pathologists; radiologists; and allied health care professionals such as dieticians, nurses and a genetic counsellor participated in presentation and discussion sessions for the purpose of developing the recommendations presented here. This consensus statement addresses current issues in the management of colorectal cancer.

Deep Learning Applied to Raman Spectroscopy for the Detection of Microsatellite Instability/MMR Deficient Colorectal Cancer

Defective DNA mismatch repair is one pathogenic pathway to colorectal cancer. It is characterised by microsatellite instability which provides a molecular biomarker for its detection. Clinical guidelines for universal testing of this biomarker are not met due to resource limitations; thus, there is interest in developing novel methods for its detection. Raman spectroscopy (RS) is an analytical tool able to interrogate the molecular vibrations of a sample to provide a unique biochemical fingerprint. The resulting datasets are complex and high-dimensional, making them an ideal candidate for deep learning, though this may be limited by small sample sizes. This study investigates the potential of using RS to distinguish between normal, microsatellite stable (MSS) and microsatellite unstable (MSI-H) adenocarcinoma in human colorectal samples and whether deep learning provides any benefit to this end over traditional machine learning models. A 1D convolutional neural network (CNN) was developed to discriminate between healthy, MSI-H and MSS in human tissue and compared to a principal component analysis–linear discriminant analysis (PCA–LDA) and a support vector machine (SVM) model. A nested cross-validation strategy was used to train 30 samples, 10 from each group, with a total of 1490 Raman spectra. The CNN achieved a sensitivity and specificity of 83% and 45% compared to PCA–LDA, which achieved a sensitivity and specificity of 82% and 51%, respectively. These are competitive with existing guidelines, despite the low sample size, speaking to the molecular discriminative power of RS combined with deep learning. A number of biochemical antecedents responsible for this discrimination are also explored, with Raman peaks associated with nucleic acids and collagen being implicated.

Tumor-independent Detection of Inherited Mismatch Repair Deficiency for the Diagnosis of Lynch Syndrome with High Specificity and Sensitivity

Lynch syndrome (LS) is the most common hereditary cancer syndrome. Early diagnosis improves prognosis and reduces health care costs, through existing cancer surveillance methods. The problem is finding and diagnosing the cancer predisposing genetic condition. The current workup involves a complex array of tests that combines family cancer history and clinical phenotypes with tumor characteristics and sequencing data, followed by a challenging task to interpret the found variant(s). On the basis of the knowledge that an inherited mismatch repair (MMR) deficiency is a hallmark of LS, we have developed and validated a functional MMR test, DiagMMR, that detects inherited MMR deficiency directly from healthy tissue without need of tumor and variant information. The validation included 119 skin biopsies collected from clinically pathogenic MMR variant carriers (MSH2, MSH6) and controls, and was followed by a small clinical pilot study. The repair reaction was performed on proteins extracted from primary fibroblasts and the interpretation was based on the MMR capability of the sample in relation to cutoff, which distinguishes MMR proficient (non-LS) from MMR deficient (LS) function. The results were compared with the reference standard (germline NGS). The test was shown to have exceptional specificity (100%) with high sensitivity (89%) and accuracy (97%). The ability to efficiently distinguish LS carriers from controls was further shown with a high area under the receiving operating characteristic (AUROC) value (0.97). This test offers an excellent tool for detecting inherited MMR deficiency linked to MSH2 or MSH6 and can be used alone or with conventional tests to recognize genetically predisposed individuals.

SIGNIFICANCE

Clinical validation of DiagMMR shows high accuracy in distinguishing individuals with hereditary MSH2 or MSH6 MMR deficiency (i.e., LS). The method presented overcomes challenges faced by the complexity of current methods and can be used alone or with conventional tests to improve the ability to recognize genetically predisposed individuals.

A Canadian Provincial Screening Program for Lynch Syndrome

INTRODUCTION

Manitoba implemented the first Canadian provincial program of reflex screening through mismatch repair immunohistochemistry (MMR-IHC) for all colorectal cancers diagnosed at age 70 years or younger in December 2017. We evaluated compliance to universal reflex testing and for referrals to Genetics for individuals with MMR-deficient tumors.

METHODS

We searched the provincial pathology database with "adenocarcinoma" in the colorectal specimen pathology reports between March 2018 and December 2020. We cross-referenced with paper and electronic records in the Program of Genetics and Metabolism to determine whether patients with MMR-deficient tumors had been referred for Genetic assessment and what proportion of patients and first-degree relatives accepted an appointment and genetic testing. We performed logistic regression analysis to identify predictors of testing.

RESULTS

We identified 3,146 colorectal adenocarcinoma specimens (biopsies and surgical resections) from 1,692 unique individuals (mean age 68.66 years, male 57%). Of those aged 70 years or younger (n = 936), 89.4% received MMR-IHC screening. Individual pathologists (categorized by the highest, average, and lowest screening rates) were the biggest predictors of MMR-IHC screening on multivariable analysis (highest vs lowest: odds ratio 17.5, 95% confidence interval 6.05-50.67). While only 53.4% (n = 31) of 58 screen-positive cases were referred by pathologists for genetic assessment, other clinicians referred an additional 22.4% (n = 13), resulting in 75.8% overall referral rate of screen-positive cases. Thirteen (1.4%) patients (1.1%, aged 70 years or younger) were confirmed to experience Lynch syndrome through germline testing, and 8 first-degree relatives (an average of 1.6 per patient) underwent cascade genetic testing.

DISCUSSION

The first Canadian Lynch syndrome screening program has achieved high rates of reflex testing.

Clinicopathological characteristics of high microsatellite instability/mismatch repair-deficient colorectal cancer: A narrative review

Colorectal cancers (CRCs) with high microsatellite instability (MSI-H) and deficient mismatch repair (dMMR) show molecular and clinicopathological characteristics that differ from those of proficient mismatch repair/microsatellite stable CRCs. Despite the importance of MSI-H/dMMR status in clinical decision making, the testing rates for MSI and MMR in clinical practice remain low, even in high-risk populations. Additionally, the real-world prevalence of MSI-H/dMMR CRC may be lower than that reported in the literature. Insufficient MSI and MMR testing fails to identify patients with MSI-H/dMMR CRC, who could benefit from immunotherapy. In this article, we describe the current knowledge of the clinicopathological features, molecular landscape, and radiomic characteristics of MSI-H/dMMR CRCs. A better understanding of the importance of MMR/MSI status in the clinical characteristics and prognosis of CRC may help increase the rates of MMR/MSI testing and guide the development of more effective therapies based on the unique features of these tumors.

Assessing Oncologists' Adoption of Biomarker Testing in Metastatic Colorectal Cancer Using Real-World Data

BACKGROUND

Despite national guideline recommendations for universal biomarker testing (KRAS, NRAS, BRAF, and mismatch repair and microsatellite instability [MMR/MSI]) in all patients with metastatic colorectal cancer (mCRC), little is known regarding adherence to these recommendations in routine practice.

METHODS

We retrospectively reviewed patients with mCRC diagnosed between January 1, 2013, and December 27, 2018, from a de-identified electronic health record-derived database. We analyzed disparities in KRAS, NRAS, BRAF, and MMR/MSI testing by race, age, sex, and insurance status using χ2 tests and t tests. We evaluated changes in biomarker testing over time with attention to changes around dates of landmark publications and guideline updates using χ2 tests and Cochran-Armitage tests.

RESULTS

A total of 20 333 patients were identified of which 66.6% had test results for any biomarker. Rates of test results for all 4 biomarkers statistically significantly increased over time (P < .001). However, as of June 30, 2018, the rate of test results was only 46% for NRAS, 56% for KRAS, and 46% for BRAF. As of December 31, 2017, the rate of MMR/MSI testing was 59%. Higher documented testing rates were associated with younger age, lower Eastern Cooperative Oncology Group performance status, and commercial insurance. There were no clinically meaningful and/or statistically significant differences in documented testing rates by tumor sidedness, race, sex, or initial stage.

CONCLUSIONS

Increased rates of documented testing for NRAS, BRAF, and MMR/MSI in mCRC was seen between 2013 and 2018 reflecting adoption of guideline recommendations. However, the rate of documented testing remains lower than expected and warrants additional research to understand the extent to which this may represent a clinical practice quality concern.

Systems approach to enhance Lynch syndrome diagnosis through tumour testing

BACKGROUND

Guidelines recommend universal mismatch repair (MMR) tumour testing of colorectal adenocarcinomas (CRCs) to screen for Lynch syndrome (LS). However, its implementation remains disjointed and referral for genetic testing dismal, particularly among minorities. We aimed to increase referral, cancer genetic testing and eventually LS diagnosis by developing the CLEAR LS (Closed Loop Enhanced Assessment and Referral for Lynch Syndrome) intervention, a systems approach which in the second phase was automated.

METHODS

This is a cohort study of all patients diagnosed with CRC at an academic centre between 1 January 2012, when implementation of universal CRC testing began, and 31 January 2021. The original cohort spanned through 31 May 2015. Tumour testing included MMR immunohistochemistry, followed by BRAF V600E/MLH1 promoter methylation testing when indicated. The intervention included a manual phase (1 June 2015 through 31 July 2018), which systematised pathology screening and cancer genetics (CG) referral mechanisms, and an automated phase (1 August 2018 through 31 January 2021) using computer programming.

RESULTS

A total of 249/1541 CRC (17.38%) had MMR loss of expression and 129 (8.37%) qualified for CG evaluation. Referral was 27.58% in the original cohort and 92.1% in the intervention (p<0.001). Patients seen by CG among referred were 27.58% in the original cohort and 74.3% in the intervention (p two-sided<0.001). The distribution of race/ethnicity among patients qualifying and referred for CG evaluation was not significantly different across cohorts. LS diagnosis increased from 0.56% (original cohort) to 1.43% (intervention). Cost per new diagnosis of LS decreased from US$173 675 to $87 960 from original cohort to intervention.

CONCLUSION

Implementation of systematic case identification and referral support mechanisms significantly increased the proportion of patients undergoing genetic testing and doubled the percentage of patients diagnosed with LS with no referral differences across racial/ethnic groups.

Deficient mismatch repair/microsatellite unstable colorectal cancer: Diagnosis, prognosis and treatment

Microsatellite unstable (MSI) colorectal cancers (CRCs) are due to DNA mismatch repair (MMR) deficiency and occurs in15% of non-metastatic diseases and 5% in the metastatic setting. Nearly 30% of MSI CRCs occur in a context of constitutional mutation of the MMR system (Lynch syndrome). Others are sporadic cancers linked to a hypermethylation of the MLH-1 promoter. The pathogenic alterations of MMR genes lead to the accumulation of frequent somatic mutational events and these tumours arbour a high antigen burden and are highly infiltrated with cytotoxic T-cell lymphocytes. Microsatellite instability/DNA mismatch repair deficiency (MSI/dMMR) status has prognostic and predictive implications in non-metastatic and metastatic CRCs. The prognostic value of MSI status in non-metastatic CRCs has been studied extensively, yet the data are more limited for its predictive value in terms of adjuvant chemotherapy efficacy. In both cases (metastatic and non-metastatic settings) treatment with immune check-point inhibitors (ICIs) have shown a remarkable effectiveness in the context of MSI/dMMR status. Indeed, recent data from prospective cohorts and randomised trials have shown a dramatical improvement of survival with immunotherapy (programmed death-ligand 1 [PD-(L)1]   cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4] blockage) in metastatic or non-metastatic MSI/dMMR CRC. In this review we report and discuss how and for whom to test for the MSI/dMMR phenotype, as well as the prognostic value of this phenotype and the new treatment recommendations options for this unique CRC population. Despite their efficacy, primary and secondary resistance to immune checkpoint inhibitors (ICIs) are observed in more than 50% MSI-H/dMMR CRC patients and in the future how to identify these patients and to overcome resistance will be an important challenge.

Underutilization of Guideline-Recommended Mismatch Repair/Microsatellite Instability Biomarker Testing in Advanced Colorectal Cancer

BACKGROUND

In 2017, DNA mismatch repair/microsatellite instability (MMR/MSI) testing was nationally recommended for advanced colorectal cancers based on favorable immune checkpoint inhibitor responses among patients with MMR-deficient/MSI-high tumors.

METHODS

Patients ages ≥20-years-old presenting with stage IV colorectal adenocarcinoma from 2010 to 2017 were identified from the National Cancer Database. 2017 was the latest year with available testing utilization data. Patient, tumor, socioeconomic, and care setting characteristics were evaluated for association with upfront MMR/MSI testing in 2017 using multivariable logistic regression and average adjusted predicted probabilities (%AAP).

RESULTS

Among 72,830 stage IV colorectal cancers, upfront MMR/MSI testing levels increased from 16.4% in 2010 to 56.4% in 2017. For patients diagnosed in 2017 (i.e., following national recommendations, n = 10,022), testing levels were lower for older patients (Padj &lt; 0.001), and were independent of patients' race/ethnicity and insurance status. Patients from the poorest quartile of households received less testing [49.6%AAP, 99.9% confidence interval (CI) 45.5-53.7] than patients from the 3rd (56.9%AAP, 99.9% CI, 53.3-60.6; Padj &lt; 0.001) or 4th quartiles (57.6%AAP, 99.9% CI, 54.3-60.9; Padj &lt; 0.001). Although testing levels improved most at community programs, they remained lower in 2017 (46.6%AAP, 99.9% CI, 41.0-52.1) compared with academic/NCI-designated comprehensive cancer centers (62.8%AAP, 99.9% CI, 59.7-65.8; Padj &lt; 0.001).

CONCLUSIONS

Upfront MMR/MSI testing utilization for patients with advanced colorectal cancer has increased but there is still substantial need for optimization. Testing utilization disproportionately lagged for patients who were older, from the poorest quartile of households, or managed at community cancer programs.

IMPACT

Our findings indicate opportunities for improving rates of MMR/MSI testing and reporting, possibly through incorporation into quality control and accreditation metrics.

Medicaid Expansions: Probing Medicaid’s Filling of the Cancer Genetic Testing and Screening Space

Cancer is the third largest source of spending for Medicaid in the United States. A working group of the American Public Health Association Genomics Forum Policy Committee reviewed 133/149 pieces of literature addressing the impact of Medicaid expansion on cancer screening and genetic testing in underserved groups and the general population. Breast and colorectal cancer screening rates improved during very early Medicaid expansion but displayed mixed improvement thereafter. Breast cancer screening rates have remained steady for Latina Medicaid enrollees; colorectal cancer screening rates have improved for African Americans. Urban areas have benefited more than rural. State programs increasingly cover BRCA1/2 and Lynch syndrome genetic testing, though testing remains underutilized in racial and ethnic groups. While increased federal matching could incentivize more states to engage in Medicaid expansion, steps need to be taken to ensure that they have an adequate distribution of resources to increase screening and testing utilization.

Interventions to improve delivery of cancer genetics services in the United States: A scoping review

PURPOSE

Interventions that decrease barriers and improve clinical processes can increase patient access to guideline-recommended cancer genetics services. We sought to identify and describe interventions to improve patient receipt of guideline-recommended cancer genetics services in the United States.

METHODS

We performed a comprehensive search in Ovid MEDLINE and Embase, Scopus, and Web of Science from January 1, 2000 to February 12, 2020. Eligible articles reported interventions to improve the identification, referral, genetic counseling (GC), and genetic testing (GT) of patients in the United States. We independently screened titles and abstracts and reviewed full-text articles. Data were synthesized by grouping articles by clinical process.

RESULTS

Of 44 included articles, 17 targeted identification of eligible patients, 14 targeted referral, 15 targeted GC, and 16 targeted GT. Patient identification interventions included universal tumor testing and screening of medical/family history. Referral interventions included medical record system adaptations, standardizing processes, and provider notifications. GC interventions included supplemental patient education, integrated GC within oncology clinics, appointment coordination, and alternative service delivery models. One article directly targeted the GT process by implementing provider-coordinated testing.

CONCLUSION

This scoping review identified and described interventions to improve US patients' access to and receipt of guideline-recommended cancer genetics services.

Analyzing Precision Medicine Utilization with Real-World Data: A Scoping Review

Precision medicine (PM), specifically genetic-based testing, is currently used in over 140,000 individual tests to inform the clinical management of disease. Though several databases (e.g., the NIH Genetic Testing Registry) demonstrate the availability of these sequencing-based tests, we do not currently understand the extent to which these tests are used. There exists a need to synthesize the body of real-world data (RWD) describing the use of sequencing-based tests to inform their appropriate use. To accomplish this, we performed a scoping review to examine what RWD sources have been used in studies of PM utilization between January 2015 and August 2021 to characterize the use of genome sequencing (GS), exome sequencing (ES), tumor sequencing (TS), next-generation sequencing-based panels (NGS), gene expression profiling (GEP), and pharmacogenomics (PGx) panels. We abstracted variables describing the use of these types of tests and performed a descriptive statistical analysis. We identified 440 articles in our search and included 72 articles in our study. Publications based on registry databases were the most common, followed by studies based on private insurer administrative claims. Slightly more than one-third (38%) used integrated datasets. Two thirds (67%) of the studies focused on the use of tests for oncological clinical applications. We summarize the RWD sources used in peer-reviewed literature on the use of PM. Our findings will help improve future study design by encouraging the use of centralized databases and registries to track the implementation and use of PM.

Patient navigation for hereditary colorectal cancer: Design of a randomized controlled trial to determine the effectiveness of pathways to genetic counseling

BACKGROUND

Diagnosis of Lynch and other hereditary colorectal cancer (CRC) syndromes through germline genetic testing has important implications for treatment and risk-management, yet guideline-recommended genetic counseling referral and attendance is suboptimal.

METHODS

Our team developed an adapted patient navigation program-Pathways to Genetic Counseling-to address multilevel barriers to genetic counseling referral and receipt. This paper describes the methods of a randomized controlled trial (RCT) testing Pathways to Genetic Counseling's effectiveness at increasing genetic counseling attendance in the University of Washington Medicine health system. We will identify CRC patients eligible for genetic counseling (diagnosed before age 50 or at any age with evidence of inherited mismatch repair deficiency) through a combination of structured electronic health record queries and manual chart review. Patients will be randomized 1:1 prior to consent and receive either care as usual (no contact) or be invited to participate in patient navigation. We will use chart review to compare rates of genetic counseling referral and attendance within six months of randomization, regardless of patients' engagement with navigation. We plan to identify and randomize 161 eligible CRC patients over a nine-month period beginning in late 2021.

DISCUSSION

Our pragmatic RCT design will provide real-world data on the potential for patient navigation to address longstanding care gaps in preventive genomic medicine. If effective, we hope to pilot Pathways to Genetic Counseling in additional settings with a long-term goal of improving appropriate diagnosis of hereditary CRC syndromes and subsequent cascade screening of eligible family members.

The emerging roles of NGS in clinical oncology and personalized medicine

Next-generation sequencing (NGS) has been increasingly popular in genomics studies over the last decade, as new sequencing technology has been created and improved. Recently, NGS started to be used in clinical oncology to improve cancer therapy through diverse modalities ranging from finding novel and rare cancer mutations, discovering cancer mutation carriers to reaching specific therapeutic approaches known as personalized medicine (PM). PM has the potential to minimize medical expenses by shifting the current traditional medical approach of treating cancer and other diseases to an individualized preventive and predictive approach. Currently, NGS can speed up in the early diagnosis of diseases and discover pharmacogenetic markers that help in personalizing therapies. Despite the tremendous growth in our understanding of genetics, NGS holds the added advantage of providing more comprehensive picture of cancer landscape and uncovering cancer development pathways. In this review, we provided a complete overview of potential NGS applications in scientific and clinical oncology, with a particular emphasis on pharmacogenomics in the direction of precision medicine treatment options.

Measuring and Improving Quality of Colonoscopy for Colorectal Cancer Screening

Colorectal cancer (CRC) is largely preventable, yet it remains a major public health issue as it is the third most common and deadly malignancy in the United States. While there are many ways to screen for CRC, colonoscopy remains the gold standard as it is the only test that is both cancer-detecting and cancer-preventing through removal of precancerous polyps. Through identifying and removing neoplastic lesions, colonoscopy reduces CRC incidence by 31%-91% and CRC mortality by 65%-88%. However, colonoscopy is not an infallible test-there is a chance for missed lesions during the exam and there is substantial variation in outcomes among endoscopists. To enhance the quality of colonoscopic exams, and ultimately to improve CRC outcomes, quality indicators have been developed for measuring endoscopists' performance. In this review, we describe the colonoscopic quality indicators and benchmarks recommended by the American Society for Gastrointestinal Endoscopy/American College of Gastroenterology Task Force on Quality in Endoscopy for screening colonoscopies in average-risk individuals. Measuring and monitoring endoscopists' performance on these measures are critical first steps in striving toward conducting high quality exams. We also review the evidence for interventions that aim to improve critical measures including adenoma detection rate, withdrawal time, cecal intubation, and bowel preparation quality. Finally, we provide a preview of the forthcoming Advancing Care for Appropriate Colon Health Merit-Based Incentive Payment System Value Pathway by the Centers for Medicare & Medicaid Services and its potential impact on clinical practice.

xDEEP-MSI: Explainable Bias-Rejecting Microsatellite Instability Deep Learning System in Colorectal Cancer

The prediction of microsatellite instability (MSI) using deep learning (DL) techniques could have significant benefits, including reducing cost and increasing MSI testing of colorectal cancer (CRC) patients. Nonetheless, batch effects or systematic biases are not well characterized in digital histology models and lead to overoptimistic estimates of model performance. Methods to not only palliate but to directly abrogate biases are needed. We present a multiple bias rejecting DL system based on adversarial networks for the prediction of MSI in CRC from tissue microarrays (TMAs), trained and validated in 1788 patients from EPICOLON and HGUA. The system consists of an end-to-end image preprocessing module that tile samples at multiple magnifications and a tissue classification module linked to the bias-rejecting MSI predictor. We detected three biases associated with the learned representations of a baseline model: the project of origin of samples, the patient's spot and the TMA glass where each spot was placed. The system was trained to directly avoid learning the batch effects of those variables. The learned features from the bias-ablated model achieved maximum discriminative power with respect to the task and minimal statistical mean dependence with the biases. The impact of different magnifications, types of tissues and the model performance at tile vs patient level is analyzed. The AUC at tile level, and including all three selected tissues (tumor epithelium, mucin and lymphocytic regions) and 4 magnifications, was 0.87 ± 0.03 and increased to 0.9 ± 0.03 at patient level. To the best of our knowledge, this is the first work that incorporates a multiple bias ablation technique at the DL architecture in digital pathology, and the first using TMAs for the MSI prediction task.

The Prevalence of Pathogenic or Likely Pathogenic Germline Variants in a Nationwide Cohort of Young Colorectal Cancer Patients Using a Panel of 18 Genes Associated with Colorectal Cancer

INTRODUCTION

The prevalence of pathogenic or likely pathogenic germline variants (PGV) in colorectal cancer (CRC) in young patients is seen in approximately one in five patients, with the majority of cases having gene variants associated with Lynch syndrome (LS). The primary aim was to describe the prevalence of 18 genes, all associated with hereditary polyposis and CRC, in a nationwide population of young CRC (yCRC) patients, and outline disease characteristics in patients with or without germline variants.

METHODS

We screened 98 patients aged 18-40 with CRC diagnosed in 2010-2013 for variants in MSH2, MSH6, MLH1, PMS2, EPCAM, APC, MUTYH, SMAD4, BMPR1A, STK11, PTEN, POLE, POLD1, NTHL1, AXIN2, MSH3, GREM1 and RNF43 using Next Generation Sequencing. Comparisons between patients' characteristics in patients with PGV, and patients without germline variants (NPGV) were analyzed.

RESULTS

PGV were detected in twenty-four patients (24.5%), and twenty-one patients (21.1%) had variants in the mismatch repair (MMR) genes associated with LS. Variants in the APC and MUTYH genes were detected in 1% and 4%, respectively. Patients with NPGV had more advanced disease with adverse histopathological features.

CONCLUSION

PGV was detected in one in four yCRC patients, and one in five yCRC patients had disease causing variants in the mismatch repair genes associated with LS.

When guidelines face reality - Lynch syndrome screening in the setting of public health system in a developing country

Lynch syndrome (LS) is the most common cause of hereditary colorectal cancer (CRC); however, it is still underrecognized and underdiagnosed. While international guidelines gravitate towards universal screening, the underuse of screening methods has been reported in real-world scenarios. This study aims to evaluate screening for LS among patients diagnosed with CRC in a public cancer center in Brazil and evaluate access to genetic counseling and testing for abnormal screens. For that purpose, all patients with CRC registered in our institution from July 2012 to December 2018 had their charts reviewed. Demographic and clinical characteristics were noted, as well as immunohistochemistry and microsatellite instability analysis results, when available. After applying exclusion criteria, a total of 1234 charts were reviewed. Among these, 257 patients were screened for LS, making up a 20.8% screening rate; when considering Jerusalem criteria, screening rate was 24.5%; for Bethesda criteria, it was 35.1%. Almost 80% of patients fulfilling Amsterdam criteria I/II were screened. There were 64 abnormal screens, from which 40 (62.5%) underwent genetic counseling and 12 (18.7%) underwent genetic testing. We concluded that overall screening rates for LS among CRC patients in a public cancer center in Brazil are low, and still very guided by stringent clinical criteria. Referral to genetic counseling and access to testing is limited, calling the whole process into question. Public policies aiming to raise awareness on hereditary cancer and include genetic testing in the public health system could help improve this scenario.

Implementation of Universal Colorectal Cancer Screening for Lynch Syndrome in Hispanics Living in Puerto Rico

OBJECTIVE

Colorectal cancer is the leading cause of cancer death in Puerto Rico and third among Hispanics in the USA. Up to 2-4% of colorectal cancer cases are a result of Lynch syndrome (LS), a hereditary cancer syndrome caused by a germline mutation in at least one of the DNA mismatch repair genes. The objective of this study was to determine the prevalence of LS in colorectal tumors during the first 15-months after the implementation of universal tumor-based screening for LS in Puerto Rico.

METHODS

A total of 317 colorectal tumors were evaluated in a large private pathology laboratory from September 2014 to December 2015. Clinical characteristics were obtained from the pathology reports. Unadjusted and adjusted logistic regression models were used to estimate the magnitude of association (odds ratio [OR] with 95% confidence intervals [CI]) between absent MMR protein expression and patient characteristics.

RESULTS

Most cases (93.4%) were analyzed by immunohistochemistry; 11.8% (35 of 296) had deficient mismatch repair protein expression. While 29 of the 317 cases were subjected to PCR-based microsatellite instability analysis of which 10.3% (3 of 317) had microsatellite instability. In total, 11.0% of the tumors were reported MMR deficient. These tumors were more likely from females and more likely localized in the proximal colon compared to those with proficient MMR expression.

CONCLUSIONS

Our data is consistent with the results from other studies including US Hispanics, where approximately 10% of Hispanic individuals with colorectal cancer have microsatellite instability. Our results support universal tumor-based screening for LS among Hispanics in accordance with National Comprehensive Cancer Network guidelines.

Atorvastatin Enhances Inhibitory Effects of Irradiation on Tumor Growth by Reducing MSH2 Expression both in Prostate Cancer Cells and Xenograft Tumor Models

BACKGROUND

Prostate cancer (PCa) is the fourth most common tumor in males.

OBJECTIVE

To investigate effects of atorvastatin (AS) on PCa cells proliferation and clarify the associated mechanisms.

METHODS

PCa cell lines were cultured and treated with irradiation (IR) (4 Gy), AS (6 μg/ml), transfected with Bcl-2 siRNA, and then divided into different groups. Xenograft tumor mouse model was established. Bcl-2 and MSH2 gene transcription and protein expression were evaluated using RT-PCR assay and western blot assay. Plate clone formation assay was employed to examine colony formation. MTT assay was used to detect cell viabilities. Flow cytometry analysis was utilized to verify apoptosis. Co-immunoprecipitation and immuno-fluorescence assay were used to identify interaction between Bcl-2 and MSH2.

RESULTS

IR significantly reduced colony formation, enhanced Bcl-2 and reduced MSH2 gene transcription in PCa cells compared to un-treated cells (p<0.05). AS significantly strengthened radio-therapeutic effects of IR on colony formation, decreased cell apoptosis and increased Bcl-2 gene transcription/protein expression in PCa cells compared to single IR treatment cells (p<0.05). AS combining IR down-regulated MSH2 gene transcription/protein expression in PCa cells compared to single IR treatment cells (p<0.05). Bcl-2 interacted with MSH2 both in PCa cells and tumor tissues administrating with AS. AS enhanced reductive effects of IR on tumor size of Xenograft tumor mice.

CONCLUSION

Atorvastatin administration enhanced inhibitory effects of IR either on PCa cells or on tumor size of Xenograft tumor mice. The inhibitory effects of atorvastatin were mediated by reducing MSH2 expression and triggering interaction between Bcl-2 and MSH2, both in vitro and in vivo levels.

Mismatch Repair Status Correlates with Survival in Young Adults with Metastatic Colorectal Cancer

BACKGROUND

Young adults with metastatic colorectal cancer (mCRC) may have higher rates of deficient mismatch repair (dMMR) than older patients. This study sought to assess patterns of MMR-testing and survival among young adult mCRC patients in the National Cancer Database (NCDB), hypothesizing that dMMR correlates with worse survival than in MMR-proficient (pMMR) patients.

METHODS

Stage-IV colorectal cancers were identified in NCDB (2010-2016). Demographic and clinical features were compared between younger (age ≤ 30) and older mCRC patients and tested for association with overall survival. Stage-IV disease without other recorded metastatic sites defined peritoneal metastasis (PM). Fisher-exact tests compared proportions and Cox models tested association with overall survival.

RESULTS

Of 124,587 stage-IV colorectal cancers, 1,123 (0.9%) were in young patients. Young patients were more likely to have mucinous histology, high-grade, rectal primaries, and isolated peritoneal metastases (P < 0.001). Younger patients more often had MMR-testing (29.1 versus 16.6%), with dMMR found at similar rates in young and older patients (21.7 versus 17.1% of those tested, P= 0.4). Despite higher rates of adverse prognostic features, younger patients had better survival (median 20.7 versus 14.8 months, P < 0.001). In MMR-tested patients, dMMR correlated with higher mortality risk compared to pMMR (median 16.6 months versus 25.5 months, P = 0.01). On multivariable analysis, grade and MMR-status remained independently associated with survival.

CONCLUSIONS

Median survival was worse with dMMR by 8.9 months compared to pMMR in young adults with mCRC. Despite higher rates of familial syndromes in young patients and recommendations for universal MMR-testing, over 70% of young mCRC patients had no MMR-status recorded.

Prospective Statewide Study of Universal Screening for Hereditary Colorectal Cancer: The Ohio Colorectal Cancer Prevention Initiative

Hereditary cancer syndromes infer high cancer risks and require intensive surveillance. Identification of high-risk individuals among patients with colorectal cancer (CRC) needs improvement.

METHODS

Three thousand three hundred ten unselected adults who underwent surgical resection for primary invasive CRC were prospectively accrued from 51 hospitals across Ohio between January 1, 2013, and December 31, 2016. Universal Tumor screening (UTS) for mismatch repair (MMR) deficiency was performed for all, and pathogenic germline variants (PGVs) were identified using multigene panel testing (MGPT) in those who met at least one inclusion criterion: MMR deficiency, diagnosed < 50 years, multiple primary tumors (CRC or endometrial cancer), or with a first-degree relative with CRC or endometrial cancer.

RESULTS

Five hundred twenty-five patients (15.9%) had MMR deficiency. Two hundred thirty-four of 3,310 (7.1%; 16% of the 1,462 who received MGPT) had 248 PGVs in cancer susceptibility genes. One hundred forty-two (4.3%) had a PGV in an MMR gene, and 101 (3.1%) had a PGV in a non-MMR gene. Ten with Lynch syndrome (LS) also had a non-MMR PGV and were included in both groups. Two (0.06%) had constitutional MLH1 hypermethylation. Of unexplained MMR-deficient patients, 88.4% (76 of 86) had double somatic MMR mutations. Testing for only MMR genes in MMR-deficient patients would have missed 18 non-MMR gene PGVs (7.3% of total PGVs identified). Had UTS been the only method used to screen for hereditary cancer syndromes, 38.6% (91 of 236) would have been missed, including 6.3% (9 of 144) of those with LS. These results have treatment implications as 5.3% (175 of 3,310) had PGVs in genes with therapeutic targets.

CONCLUSION

UTS alone is insufficient for identifying a large proportion of CRC patients with hereditary syndromes, including some with LS. At a minimum, 7.1% of individuals with CRC have a PGV and pan-cancer MGPT should be considered for all patients with CRC.

How Should We Test for Lynch Syndrome? A Review of Current Guidelines and Future Strategies

International guidelines for the diagnosis of Lynch syndrome (LS) recommend molecular screening of colorectal cancers (CRCs) to identify patients for germline mismatch repair (MMR) gene testing. As our understanding of the LS phenotype and diagnostic technologies have advanced, there is a need to review these guidelines and new screening opportunities. We discuss the barriers to implementation of current guidelines, as well as guideline limitations, and highlight new technologies and knowledge that may address these. We also discuss alternative screening strategies to increase the rate of LS diagnoses. In particular, the focus of current guidance on CRCs means that approximately half of Lynch-spectrum tumours occurring in unknown male LS carriers, and only one-third in female LS carriers, will trigger testing for LS. There is increasing pressure to expand guidelines to include molecular screening of endometrial cancers, the most frequent cancer in female LS carriers. Furthermore, we collate the evidence to support MMR deficiency testing of other Lynch-spectrum tumours to screen for LS. However, a reliance on tumour tissue limits preoperative testing and, therefore, diagnosis prior to malignancy. The recent successes of functional assays to detect microsatellite instability or MMR deficiency in non-neoplastic tissues suggest that future diagnostic pipelines could become independent of tumour tissue.

Artificial Intelligence for Histology-Based Detection of Microsatellite Instability and Prediction of Response to Immunotherapy in Colorectal Cancer

Microsatellite instability (MSI) is a molecular marker of deficient DNA mismatch repair (dMMR) that is found in approximately 15% of colorectal cancer (CRC) patients. Testing all CRC patients for MSI/dMMR is recommended as screening for Lynch Syndrome and, more recently, to determine eligibility for immune checkpoint inhibitors in advanced disease. However, universal testing for MSI/dMMR has not been uniformly implemented because of cost and resource limitations. Artificial intelligence has been used to predict MSI/dMMR directly from hematoxylin and eosin (H&E) stained tissue slides. We review the emerging data regarding the utility of machine learning for MSI classification, focusing on CRC. We also provide the clinician with an introduction to image analysis with machine learning and convolutional neural networks. Machine learning can predict MSI/dMMR with high accuracy in high quality, curated datasets. Accuracy can be significantly decreased when applied to cohorts with different ethnic and/or clinical characteristics, or different tissue preparation protocols. Research is ongoing to determine the optimal machine learning methods for predicting MSI, which will need to be compared to current clinical practices, including next-generation sequencing. Predicting response to immunotherapy remains an unmet need.

Metastatic Colorectal Cancers with Mismatch Repair Deficiency Result in Worse Survival Regardless of Peritoneal Metastases

BACKGROUND

Mismatch-repair deficiency (dMMR) predicts worse chemoresponsiveness but better survival in early-stage colorectal adenocarcinoma. This study examined metastatic colorectal and appendix cancers with and without peritoneal metastasis (PM) in the National Cancer Database (NCDB), hypothesizing that dMMR tumors show better survival.

METHODS

Stage 4 colon, rectum, and appendix cancers (2010-2016) were identified in the NCDB (including goblet cell carcinoids, excluding neuroendocrine tumors). Stage 4 disease without liver, bone, brain, lung, or distant nodal metastases defined PM. Fisher's exact tests were used to compare proportions, and Kaplan-Meier analysis was used to evaluate survival.

RESULTS

Of 130,125 stage 4 colon, rectum, and appendix cancers, 27,848 (21.4%) had PM. Appendix primary tumors had PM more commonly than colon or rectum cancer (83.6% vs. 20.6% and 12.1% of stage 4 cases; p < 0.0001). More PM patients had MMR testing than patients with other metastasis (OM) (21.4% vs. 16.1%), and testing increased from 9.6% in 2010 to 26.3% in 2016 (both p < 0.0001). Among the PM patients, MMR testing was least common for appendix cancers (9.0%). When tested, PM patients more often had dMMR (22.9% [1122/4900] vs. 15.4% [2532/16,495] of OM patients; p < 0.0001). Colon primary tumor had dMMR most frequently (25.0% vs. 14.6% and 14.5% for rectal and appendix tumor; p < 0.0001). Most PM patients received chemotherapy (66.2%). Immunotherapy use increased over time (1.1% of PM diagnoses in 2010 vs. 20.8% in 2016). For MMR-tested stage 4 patients, dMMR correlated with worse survival (median OM, 19.7 vs. 23.9 months, p < 0.0001; median PM, 19.9 vs. 24.6 months, p = 0.035).

CONCLUSIONS

The NCDB showed dMMR predicting worse survival for stage 4 colorectal cancers with and without PM and dMMR existing in 14.5-25% of tested patients, suggesting that increased attention to MMR testing in stage 4 colorectal and appendix cancers can identify many patients who could potentially benefit from immunotherapy.

Underutilization of Lynch Syndrome Screening at Two Large Veterans Affairs Medical Centers

BACKGROUND

Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) syndrome, yet is grossly under-recognized. Multiple professional societies recommend screening all CRCs for LS by performing tumor testing. The veterans affairs system has not adopted universal tumor testing as a national performance metric and leaves screening for LS to clinical care at individual sites.

AIMS

Describe adherence to LS screening in the VA system.

METHODS

Dual-center, retrospective review of all CRCs diagnosed between 2010 and 2016. Rates of tumor testing, personal and family history of cancer were extracted from the medical record. Univariate and multivariate regression analysis was performed to determine predictors of tumor-based screening for LS.

RESULTS

A total of 421 cancers were reviewed. 15.1% of all cancers underwent either MSI and/or IHC for LS screening over the study period. There was improvement in LS screening from 3% of all CRCs in 2010 to 45% of all CRCs in 2016. 34% and 70% of patients did not have documentation of CRC in first- and second-degree relatives, respectively. Of the 73 patients who met one of the Revised Bethesda Criteria or had a PREMM1,2,6 score of ≥ 5, 34% and 56% underwent tumor testing, respectively. Younger age, non-Caucasian race, meeting Bethesda or PREMM1,2,6 criteria and right-sided tumor location were predictors of undergoing tumor testing.

CONCLUSIONS

CRC tumor screening for LS is grossly inadequate when left to routine clinical care. Our results lend support to implementation of reflexive universal tumor testing within the VA system.

Developing Pathology Measures for the Quality Payment Program-Part I: A Quest for Meaningful Measures

CONTEXT.—

Quality measures assess health care processes, outcomes, and patient perceptions associated with high-quality health care, which is commonly defined as care that is effective, safe, efficient, patient centered, equitable, and timely. Such measures are now being used in order to incentivize provision of high-quality health care.

OBJECTIVE.—

To meet the goals of the Quality Payment Program, quality measures will be developed from clinical practice guidelines and relevant, peer-reviewed research identifying evidence that the measure addresses 3 areas: a high-priority aspect of health care or a specific national health goal or priority; a meaningful focus, such as leading to a desired health outcome; and a gap or variation in care.

DESIGN.—

Within the College of American Pathologists (CAP), the Measures and Performance Assessment Subcommittee is tasked with developing useful performance measures. Participating practitioners can then select measures that are meaningful to their respective patients and practices, and reflect the quality of the services they provide.

RESULTS.—

The CAP developed 23 quality measures for reporting to the Centers for Medicare & Medicaid Services that reflect rigorous clinical evidence and address areas in need of performance improvement.

CONCLUSIONS.—

Because the implications of reporting on these pathology-specific metrics are significant, these measures and the process by which they were designed are presented here in peer-reviewed fashion. The measures described in this article (part 1) represent recent efforts by the CAP to develop meaningful measures that reflect rigorous clinical evidence and highlight areas with opportunities for performance improvement.

Worldwide variation in lynch syndrome screening: case for universal screening in low colorectal cancer prevalence areas

To perform a systematic assessment of universal Lynch syndrome (LS) screening yield in colorectal cancer (CRC) patients around the world. Universal screening for LS is recommended in all CRC patients. However, the variation in yield of LS screening in the setting of significant global variation in CRC prevalence is unknown. A systematic review of articles in the MEDLINE database was performed to identify studies performing universal screening for LS. All cases with microsatellite instability (MSI-H) or missing one or more proteins on immunohistochemistry (IHC) were considered screening positive. The overall pooled yield of universal LS screening in 97 study arms from 89 identified studies was 11.9% (5649/47545) and the overall pooled percentage of confirmed LS patients was 1.8% (682/37220). LS screening positivity varied significantly based on geographic region (Kruskal Wallis test, p < 0.001) and reported 5-year CRC prevalence in the country (Fisher's exact, p < 0.001). Significant inverse correlation was found between LS screening positivity and 5-year CRC prevalence (Pearson correlation, r =  - 0.56, p < 0.001). The overall yield of LS screening was 15.00% (382/2553) and rate of confirmed LS was 7.7% (113/1475) in LS screening done in patients ≤ 50 years (16 studies). There is significant geographic variation in LS screening positivity with higher yield in countries with lower prevalence of CRC. Our results highlight the importance of universal LS screening in younger patients and low CRC prevalence countries.

An action plan to address the rising burden of colorectal cancer in younger adults

Aim: The National Colorectal Cancer Roundtable convened a national Summit to discuss the causes of early-onset colorectal cancer and clinical challenges to mitigating burden of this disease. Materials & methods: Information presented was synthesized through scientific consensus building to determine priorities for new research and practice change. Results: Research priorities include evaluating role of novel risk factors, understanding natural history and identifying ways to implement evidenced-based practices for identifying and managing at-risk persons. Practice change should focus on adoption of guidelines for collecting family history, screening in young adults at risk, provider and population awareness about risk and symptoms, and universal tumor testing. Conclusion: Successful implementation of strategies to address research and practice change will require collaboration from multiple partners.

Atorvastatin Enhances Effects of Radiotherapy on Prostate Cancer Cells and Xenograft Tumor Mice Through Triggering Interaction Between Bcl-2 and MSH2

BACKGROUND Prostate cancer (PCa) is considered to be the 4th most common cancer in males in the world. This study aimed to explore effects of atorvastatin on colony formation of PCa cells and radio-resistance of xenograft tumor models. MATERIAL AND METHODS PCa cell lines, including PC3, DU145, and Lncap, were treated with irradiation (4 Gy) and/or atorvastatin (6 μg/mL). Cells were divided into tumor cell group, irradiation treatment group (IR group) and irradiation+atorvastatin treatment group (IR-AS group). Xenograft tumor mouse model was established. Plate clone formation assay (multi-target/single-hit model) was conducted to evaluate colony formation. Flow cytometry analysis was employed to detect apoptosis. Interaction between Bcl-2 and MSH2 was evaluated with immuno-fluorescence assay. RESULTS According to the plate colony formation assay and multi-target/single-hit model, IR-treatment significantly suppressed colony formation in PCa cells (including PC3, DU145, and Lncap cells) compared to no-IR treated cells (P<0.05). Atorvastatin remarkably enhanced inhibitive effects of irradiation on colony formation of PCa cells (P<0.05), however, the IR+AS group demonstrated no effects on apoptosis, comparing to IR group (P>0.05). Atorvastatin administration (IR+AS group) significantly reduced tumor size of IR-treated PCa cells-induced xenograft tumor mice (P<0.05). Bcl-2 interacted with MSH2 both in tumor tissues of xenograft tumor mice. CONCLUSIONS Atorvastatin administration inhibited colony formation in PCa cells and enhanced effects of radiotherapy on tumor growth of xenograft tumor mice, which might be associated with interaction between Bcl-2 and MSH2 molecule.

Experience of mismatch repair/microsatellite instability (MMR/MSI) testing among patients with advanced/metastatic colorectal cancer in the US

Objective: We assessed knowledge and awareness of MMR/MSI testing among advanced/metastatic CRC patients in the US who had previously taken the test.Methods: A non-interventional, cross-sectional online survey was conducted among 150 US CRC patients invited through a research panel. Eligible patients had to be ≥18 years, with stage III or IV CRC (self-reported), had undergone MMR/MSI testing for CRC in past 12 months and could recall the test, and provided informed consent. Descriptive analyses were performed.Results: 81.3% of patients received MMR/MSI testing information from their doctor. Of 64.7% of patients who were a member of a patient support group, 86.6% received information from their groups. Most patients (82.7%) also searched for information on their own (internet searches). Most patients (93.5 to 96.9%) were satisfied with information received from these sources. Reasons for having testing done included increasing knowledge about their cancer (69.3%), being beneficial to determining treatment options (60.7%), and doctor recommendation (62.7%). Key barriers to testing included personal reservations regarding benefits of the test (29.3%), insurance coverage (27.3%), and out-of-pocket costs (18.7%); 45.3% reported no barriers.Conclusions: Patients were well informed about MMR/MSI testing. Increased education of testing benefits and addressing financial barriers may help to further improve testing rates.

Shrestha T, Zilfalil BA. MLH1 and MSH2 mismatch repair protein profile using immunohistochemistry in Nepalese colorectal cancer patients

BACKGROUND Hereditary nonpolyposis colorectal cancer, or Lynch syndrome, caused by germline mutations or genetic defects in mismatch repair (MMR) genes (MLH1, MSH2, PMS2, MSH6, and epithelial cellular adhesion molecule), is an autosomal dominant condition accounting for 2–5% of all colorectal carcinomas (CRCs). Reports on MMR loss in many populations are available; however, there are no reports on the frequency of MMR protein expression in Nepalese cohorts. Therefore, this study was aimed to assess the expression profiles of MLH1 and MSH2 protein by immunohistochemistry (IHC) in Nepalese CRC patients. METHODS This retrospective study used archived formalin-fixed paraffin-embedded tissue blocks from 43 Nepalese CRC patients. IHC staining was performed using MLH1 and MSH2 antibodies. IHC scoring analysis was assessed using semiquantitative scoring. RESULTS Of the 43 CRC patients, 8 (18.6%) showed loss of staining for MLH1 antibody, 5 (11.6%) showed loss of staining for MSH2 antibody, and 4 (9.3%) showed loss of staining for both MLH1 and MSH2 antibodies. CONCLUSIONS IHC is a potential screening method of determining the MMR expression profile of Nepalese CRC patients. IHC can be performed in local clinical laboratories to find MMR protein defects in selected cases prior to expensive molecular tests.

Association of KRAS mutation with tumor deposit status and overall survival of colorectal cancer

PURPOSE

To examine associations of KRAS mutation with tumor deposit status and overall survival in colorectal cancer (CRC) patients.

METHODS

This retrospective cohort study included patients with incidental CRC diagnosed during 2010-2014 and recorded statuses of KRAS and tumor deposit in the National Cancer Database of the USA. Multivariable logistic regression and time-varying Cox regression analyses were used.

RESULTS

We included 45,761 CRC patients with KRAS status (24,027 [52.5%] men, 24,240 [53.0%] < 65 years old, 17,338 [37.9%] with KRAS mutation). Adjusted for microsatellite instability, age, pathologic stage and tumor grade, KRAS mutation (versus wild type) was associated with tumor deposit presence (odds ratio = 1.11, 95% CI 1.02-1.20). KRAS mutation was also linked to worse overall survival of CRC patients regardless of tumor deposit status (adjusted Hazard ratio [HR] = 1.20, 95% CI 1.07-1.33 for CRC with tumor deposits, and adjusted HR = 1.24, 95% CI 1.14-1.35 or CRC without) or tumor stage (adjusted HR = 1.32, 95% CI 1.14-1.54 for early-stage and adjusted HR = 1.18, 95% CI 1.10-1.27 for late-stage). Microsatellite instability was associated with better overall survival in CRC without tumor deposit (adjusted HR = 0.89, 95% CI 0.79-0.99), but not in CRC with tumor deposit (adjusted HR = 1.12, 95% CI 0.97-1.30).

CONCLUSION

KRAS mutation is independently associated with tumor deposit presence and a worse overall survival in CRC patients.

Organizational readiness to implement population-based screening and genetic service delivery for hereditary cancer prevention and control

Despite clinical guidelines, programs conducting population-based screening and genetic service delivery for hereditary cancer prevention and control are rare in practice. We interviewed individuals (n = 13) instrumental in implementing seven unique clinical programs conducting either universal tumor screening for Lynch Syndrome or routine family history screening and provision of genetic services for hereditary breast and ovarian cancer in the United States. To characterize determinants of readiness to implement population-based cancer genetic service delivery models, interviews and deductive codes drew on Weiner's theory of organizational readiness for change. Qualitative analysis identified themes across programs. The degree to which organizational stakeholders valued moving to a population-based genetic service delivery model depended on the existence of aligned clinical guidelines at the time of program implementation. However, judgments of implementation capacity within the organization, particularly with respect to task demands and resource concerns, were more often barriers to readiness. Program champions were essential to facilitating readiness, frequently taking on substantial uncompensated work. These data suggest that developing interventions targeting change efficacy and cultivating practice change champions may be two promising ways to increase uptake of population-based hereditary cancer screening and genetic service delivery in clinical practice.

Sequencing-based microsatellite instability testing using as few as six markers for high-throughput clinical diagnostics

Microsatellite instability (MSI) testing of colorectal cancers (CRCs) is used to screen for Lynch syndrome (LS), a hereditary cancer-predisposition, and can be used to predict response to immunotherapy. Here, we present a single-molecule molecular inversion probe and sequencing-based MSI assay and demonstrate its clinical validity according to existing guidelines. We amplified 24 microsatellites in multiplex and trained a classifier using 98 CRCs, which accommodates marker specific sensitivities to MSI. Sample classification achieved 100% concordance with the MSI Analysis System v1.2 (Promega) in three independent cohorts, totaling 220 CRCs. Backward-forward stepwise selection was used to identify a 6-marker subset of equal accuracy to the 24-marker panel. Assessment of assay detection limits showed that the 24-marker panel is marginally more robust to sample variables than the 6-marker subset, detecting as little as 3% high levels of MSI DNA in sample mixtures, and requiring a minimum of 10 template molecules to be sequenced per marker for >95% accuracy. BRAF c.1799 mutation analysis was also included to streamline LS testing, with all c.1799T>A variants being correctly identified. The assay, therefore, provides a cheap, robust, automatable, and scalable MSI test with internal quality controls, suitable for clinical cancer diagnostics.

Genomic Profiling for KRAS, NRAS, BRAF, Microsatellite Instability, and Mismatch Repair Deficiency Among Patients With Metastatic Colon Cancer

PURPOSE

Genomic testing is recognized in national guidelines as essential to guide appropriate therapy selection in metastatic colorectal cancer. Previous studies report adherence to testing guidelines is suboptimal, but current testing rates have not been assessed. This study reports testing rates in metastatic colon cancer (mCC) for guideline-recommended biomarkers in a US-based population.

MATERIALS AND METHODS

A retrospective review of data extracted from electronic medical records was performed to identify patients with pathologically confirmed mCC and describe patterns of guideline-aligned biomarker testing. Data were extracted from the electronic health records of 1,497 patients treated at 23 practices across the United States. Both community and academic centers were represented.

RESULTS

A total of 1,497 patients with mCC diagnosed between January 1, 2013 and December 31, 2017 were identified. Guideline-aligned biomarker testing rates for RAS, BRAF, and microsatellite instability/mismatch repair deficiency over this study period were 41%, 43%, and 51%, respectively. Patients were more likely to have guideline-aligned testing for RAS and BRAF if they were treated at an academic center, were diagnosed with de novo metastatic disease, and were female. In addition, patients < 65 years of age were more likely to have guideline-aligned RAS testing. Of the 177 patients (12% of cohort) who received anti-epidermal growth factor receptor therapy, only 50 (28%) had complete guideline-aligned biomarker testing.

CONCLUSION

Despite guideline recommendations and significant therapeutic implications, overall biomarker testing rates in mCC remain suboptimal. Adherence to guideline-recommended biomarker testing would potentially reduce exposure to expensive and ineffective therapies, resulting in improved patient outcomes.

The Current Practice of Lynch Syndrome Diagnosis and Management in Italy: A Qualitative Assessment

BACKGROUND

Lynch syndrome (LS) is the most frequent form of hereditary colorectal cancer (CRC; up to 3-5% of the total CRC burden) and predisposes to the development of other cancers. Multidisciplinary diagnostic strategies are relevant both to the index cases and to their at-risk relatives, but their implementation is still limited. Our study aimed to explore LS testing practices in Italy.

METHODS

In order to ascertain the current practice of LS diagnosis and management, we conducted a qualitative assessment by sending a questionnaire to health care professionals at 4 Italian hospitals selected as "models" representing different hospital settings. Based on the surveys, we reconstructed the management pathways for CRC patients in terms of diagnostic strategies and health professionals involved.

RESULTS

Seven of the 8 invited professionals filled in the questionnaire. Noncompliance with the latest guidelines was reported, as no tumor "screening" was performed on CRC cases. The lack of a structured multidisciplinary team who manages CRC patients from risk assessment to diagnosis and follow-up was reported. The availability of professionals and laboratory technologies differ widely between hospitals. As for cascade testing of at-risk relatives, a systematic and active approach was absent in all the considered hospitals.

CONCLUSIONS

Our study shows that no structured and standardized pathways for the diagnosis and management of LS patients are currently in place in Italy. We envisage that by extending our research to further experiences and countries, an increasing awareness of the topic can be translated into a health gain for hereditary CRC patients and their at-risk relatives.

Suboptimal Adherence in Clinical Practice to Guidelines Recommendation to Screen for Lynch Syndrome

BACKGROUND

Identification of Lynch syndrome (LS) followed by annual/biannual surveillance colonoscopy markedly reduces the risk of developing new colorectal cancer (CRC) among those with LS.

AIMS

(1) To determine the current practice of identifying LS in the USA and Canada, and current surveillance and management practices for those diagnosed with LS; (2) to determine whether variances in current practice are physician/region dependent or influenced by ease of access to specialist clinics.

METHODS

An online survey request was sent to practicing gastroenterologists through the Canadian Association of Gastroenterology and the American College of Gastroenterology. Fisher's exact tests were performed to determine the factors associated with screening for LS and separately for follow-up, surveillance, and management.

RESULTS

A total of 249 participants were recruited, of which 237 were gastroenterologists and included in the analysis. Less than one-third of practicing gastroenterologists indicated that their CRC patients were undergoing screening tests to identify LS. While 42% (65/153) of participants from the USA stated that their patients were undergoing universal LS screening (i.e., among all diagnosed with CRC), only 12% (6/49) of participants from Canada reported this practice (p < 0.001). There was no difference in reported practice between the physicians that do and do not have access to hereditary clinics (35% vs. 34% testing; p = 0.54). Appropriate surveillance interval to look for CRC in patients with LS was recommended by most.

CONCLUSION

This survey suggests there is a significant difference in practice between Canada and the USA in regard to identification of LS, with suboptimal practice throughout North America.

Validation of Microsatellite Instability Detection Using a Comprehensive Plasma-Based Genotyping Panel

PURPOSE

To analytically and clinically validate microsatellite instability (MSI) detection using cell-free DNA (cfDNA) sequencing.

EXPERIMENTAL DESIGN

Pan-cancer MSI detection using Guardant360 was analytically validated according to established guidelines and clinically validated using 1,145 cfDNA samples for which tissue MSI status based on standard-of-care tissue testing was available. The landscape of cfDNA-based MSI across solid tumor types was investigated in a cohort of 28,459 clinical plasma samples. Clinical outcomes for 16 patients with cfDNA MSI-H gastric cancer treated with immunotherapy were evaluated.

RESULTS

cfDNA MSI evaluation was shown to have high specificity, precision, and sensitivity, with a limit of detection of 0.1% tumor content. In evaluable patients, cfDNA testing accurately detected 87% (71/82) of tissue MSI-H and 99.5% of tissue microsatellite stable (863/867) for an overall accuracy of 98.4% (934/949) and a positive predictive value of 95% (71/75). Concordance of cfDNA MSI with tissue PCR and next-generation sequencing was significantly higher than IHC. Prevalence of cfDNA MSI for major cancer types was consistent with those reported for tissue. Finally, robust clinical activity of immunotherapy treatment was seen in patients with advanced gastric cancer positive for MSI by cfDNA, with 63% (10/16) of patients achieving complete or partial remission with sustained clinical benefit.

CONCLUSIONS

cfDNA-based MSI detection using Guardant360 is highly concordant with tissue-based testing, enabling highly accurate detection of MSI status concurrent with comprehensive genomic profiling and expanding access to immunotherapy for patients with advanced cancer for whom current testing practices are inadequate.See related commentary by Wang and Ajani, p. 6887.

Effective Identification of Lynch Syndrome in Gastroenterology Practice

Purpose of review:

Identification of Lynch syndrome is important from an individual patient and public health standpoint. As paradigms for Lynch syndrome diagnosis have shifted in recent years, this review will discuss rationale and limitations for current strategies as well as provide an overview of future directions in the field.

Recent findings:

In recent years, the use of clinical criteria and risk scores for identification of Lynch syndrome have been augmented by universal testing of all newly diagnosed colorectal cancers with molecular methods to screen for mismatch repair deficiency with high sensitivity and specificity. Studies of implementation and outcomes of universal testing in clinical practice have demonstrated significant heterogeneity that results in suboptimal uptake and contributes to disparities in diagnosis. Emerging technologies, such as next-generation sequencing, hold significant promise as a screening strategy for Lynch syndrome.

Summary:

Universal testing for Lynch syndrome is being performed with increasing frequency, although real-world outcomes have demonstrated room for improvement. Future directions in Lynch syndrome diagnosis will involve optimization of universal testing workflow and application of new genetics technologies.

NCCN Guidelines Insights: Genetic/Familial High-Risk Assessment: Colorectal, Version 2.2019

Identifying individuals with hereditary syndromes allows for improved cancer surveillance, risk reduction, and optimized management. Establishing criteria for assessment allows for the identification of individuals who are carriers of pathogenic genetic variants. The NCCN Guidelines for Genetic/Familial High-Risk Assessment: Colorectal provide recommendations for the assessment and management of patients with high-risk colorectal cancer syndromes. These NCCN Guidelines Insights focus on criteria for the evaluation of Lynch syndrome and considerations for use of multigene testing in the assessment of hereditary colorectal cancer syndromes.

Mismatch Repair/Microsatellite Instability Testing Practices among US Physicians Treating Patients with Advanced/Metastatic Colorectal Cancer

The study objective was to assess US physicians’ Mismatch Repair/Microsatellite Instability (MMR/MSI) testing practices for metastatic colorectal cancer (mCRC) patients. A non-interventional, cross-sectional online survey was conducted among 151 physicians (91 oncologists, 15 surgeons and 45 pathologists) treating mCRC patients in the US. Eligible physicians were US-based with at least 5 years of experience treating CRC patients, had at least one mCRC patient in their routine care in the past 6 months, and had ordered at least one MMR/MSI test for CRC in the past 6 months. Descriptive and logistic regression analyses were performed. Awareness of specific MMR/MSI testing guidelines was high (n = 127, 84.1%). Of those, 93.7% (119/127) physicians had awareness of specific published guidelines with majority 67.2% (80/119) being aware of National Comprehensive Cancer Network (NCCN) guidelines. Universal testing for all CRC patients was performed by 68.9% (104/151) physicians, while 29.8% (45/151) selectively order the test for some CRC patients. Key barriers for testing included insufficient tissue sample (48.3%, 73/151), patient declined to have the test done (35.8%, 54/151) and insurance cost concerns for patients (31.1%, 47/151), while 27.2% (41/151) reported no barriers. The survey demonstrated high awareness and compliance with MMR/MSI testing guidelines although universal testing rates seem to be suboptimal.

Lynch Syndrome: From Screening to Diagnosis to Treatment in the Era of Modern Molecular Oncology

Lynch syndrome is a hereditary cancer predisposition syndrome caused by germline alterations in the mismatch repair genes and is the most common etiology of hereditary colorectal cancer. While Lynch syndrome was initially defined by the clinical Amsterdam criteria, these criteria lack the sensitivity needed for clinical utility. This review covers the evolution of screening for Lynch syndrome from the use of tumor microsatellite instability and/or somatic alterations in mismatch repair protein expression by immunohistochemistry to the newest methods using next-generation sequencing. Additionally, it discusses the clinical implications of the diagnosis of Lynch syndrome as it affects cancer therapeutics and the role of screening in noncolorectal Lynch-associated cancers. As molecular oncology continues to evolve, it is crucial to remain current on the increasing complexity of Lynch syndrome diagnostics and treatment options.