Form Of Hereditary Colorectal Cancer Research Articles

A Highly Sensitive Pan-Cancer Test for Microsatellite Instability

Microsatellite instability (MSI) is an evolving biomarker for cancer detection and treatment. MSI was first used to identify patients with Lynch syndrome, a hereditary form of colorectal cancer (CRC), but has recently become indispensable in predicting patient response to immunotherapy. To address the need for pan-cancer MSI detection, a new multiplex assay was developed that uses novel long mononucleotide repeat (LMR) markers to improve sensitivity. A total of 469 tumor samples from 20 different cancer types, including 319 from patients with Lynch syndrome, were tested for MSI using the new LMR MSI Analysis System. Results were validated by using deficient mismatch repair (dMMR) status according to immunohistochemistry as the reference standard and compared versus the Promega pentaplex MSI panel. The sensitivity of the LMR panel for detection of dMMR status by immunohistochemistry was 99% for CRC and 96% for non-CRC. The overall percent agreement between the LMR and Promega pentaplex panels was 99% for CRC and 89% for non-CRC tumors. An increased number of unstable markers and the larger size shifts observed in dMMR tumors using the LMR panel increased confidence in MSI determinations. The LMR MSI Analysis System expands the spectrum of cancer types in which MSI can be accurately detected.

Barriers in the identification and diagnosis of hereditary colon cancer.

e13524 Background: Lynch Syndrome (LS), the most common form of hereditary colorectal cancer (CRC), is due to germline pathogenic variant (PV) in mismatch repair genes (MMR). Since 2009, the National Comprehensive Cancer Network (NCCN) recommends MMR screening for LS for all CRCs regardless of age. The American College of Medical Genetics and Genomics recommends patients with MMR deficiency or microsatellite instability (MSI) be referred for genetic testing. Despite these recommendations, compliance is low. The aim of this study was to evaluate compliance with LS screening and genetic testing in CRC. Methods: A single institution retrospective review of patients diagnosed with CRC from 2018-2021 was performed. A chart review of those diagnosed in 2018 and 2021 was analyzed and combined as a single population from pre and post COVID periods. A student’s T-Test was used to compare continuous variables and chi square for categorical variables within the two populations. The compliance with either MSI or MMR screening was calculated. Meeting criteria for genetic testing was defined as age less than 50, MSI-L/H or MMR deficient. These patients were then analyzed to determine the proportion of genetic referrals, genetic counseling, genetic testing and identification of LS. Results: 276 patients with CRC were reviewed, 153 in 2018, 123 in 2021. 71.2% were Caucasian and 58% male. There was no statistically significant difference in gender, race or ethnicity, however, there was a difference in age, with a younger average age in 2021 (67, 63; p = 0.014). 146 (53%) patients were screened for LS. 44 (16%) with MSI, 19 (7%) MMR and 82 (30%) with both. 78 patients met criteria for genetic testing; 47 due to age alone, 6 age and positive LS screening and 25 screening alone. 35% (27/78) of those meeting criteria were referred to genetics, of which 63% (17/27) completed their appointment, 63% (17/27) were tested, and 37% (10/27) had a PV identified. Conclusions: Despite guidelines for LS screening, compliance is low with only half of CRC patients appropriately screened at our institution. Even patients with positive screening and those less than 50 were not referred for genetic testing. However, of referred patients, 63% completed their appointment and all those were tested. This supports the idea that poor compliance with genetic testing is not due to patient compliance, but shows a systems issue at a higher level. To improve LS identification, reflex screening and genetic referrals are paramount. In our study, 59% of patients with germline testing had a PV, however 65% of those meeting criteria were never referred, which could reflect a proportion of patients with LS going unidentified. This validates the 2022 NCCN guidelines recommending genetic testing for all CRCs despite age or MSI/MMR status. By removing the barrier of MMR testing, more genetic testing will likely be done. [Table: see text]

MiR-137 Targets the 3' Untranslated Region of MSH2: Potential Implications in Lynch Syndrome-Related Colorectal Cancer.

Simple SummaryIn a previous study, we identified a patient carrying the variant c.*226A>G in the MSH2 3′ untranslated region that showed overexpression of MSH2 protein. In this study, we hypothesized that the MSH2 3′UTR contained a seed region for miR-137, indicating MSH2 was indeed targeted by miR-137. Our in vitro studies showed an inverse correlation between miR-137 and MSH2; this functional interaction was also confirmed in normal and tumoral tissue samples from the patient carrying the c.*226A>G variant in the MSH2 3′UTR.Mismatch Repair (MMR) gene dysregulation plays a fundamental role in Lynch Syndrome (LS) pathogenesis, a form of hereditary colorectal cancer. Loss or overexpression of key MMR genes leads to genome instability and tumorigenesis; however, the mechanisms controlling MMR gene expression are unknown. One such gene, MSH2, exerts an important role, not only in MMR, but also in cell proliferation, apoptosis, and cell cycle control. In this study, we explored the functions and underlying molecular mechanisms of increased MSH2 expression related to a c.*226A>G variant in the 3′untranslated (UTR) region of MSH2 that had been previously identified in a subject clinically suspected of LS. Bioinformatics identified a putative binding site for miR-137 in this region. To verify miRNA targeting specificity, we performed luciferase gene reporter assays using a MSH2 3′UTR psiCHECK-2 vector in human SW480 cells over-expressing miR-137, which showed a drastic reduction in luciferase activity (p > 0.0001). This effect was abolished by site-directed mutagenesis of the putative miR-137 seed site. Moreover, in these cells we observed that miR-137 levels were inversely correlated with MSH2 expression levels. These results were confirmed by results in normal and tumoral tissues from the patient carrying the 3′UTR c.*226A>G variant in MSH2. Finally, miR-137 overexpression in SW480 cells significantly suppressed cell proliferation in a time- and dose-dependent manner (p < 0.0001), supporting a role for MSH2 in apoptosis and cell proliferation processes. Our findings suggest miR-137 helps control MSH2 expression via its 3′UTR and that dysregulation of this mechanism appears to promote tumorigenesis in colon cells.

Universal Immunohistochemistry for Lynch Syndrome: A Systematic Review and Meta-analysis of 58,580 Colorectal Carcinomas

Lynch syndrome is a form of hereditary colorectal cancer (CRC) caused by pathogenic germline variants (PV) in DNA mismatch repair (MMR) genes. Currently, many Western countries perform universal immunohistochemistry testing on CRC to increase the identification of Lynch syndrome patients and their relatives. For a clear understanding of health benefits and costs, data on its outcomes are required: proportions of Lynch syndrome, sporadic MMR-deficient (MMRd) cases, and unexplained MMRd cases. Ovid Medline, Embase, and Cochrane CENTRAL were searched for studies reporting on universal MMR immunohistochemistry, followed by MMR germline analysis, until March 20, 2020. Proportions were calculated, subgroup analyses were performed based on age and diagnostics used, and random effects meta-analyses were conducted. Quality was assessed using the Joanna Briggs Critical Appraisal Tool for Prevalence Studies. Of 2723 identified articles, 56 studies covering 58,580 CRCs were included. In 6.22% (95% CI, 5.08%-7.61%; I2= 96%) MMRd was identified. MMR germline PV was present in 2.00% (95% CI, 1.59%-2.50%; I2= 92%), ranging from 1.80% to 7.27% based on completeness of diagnostics and age restriction. Immunohistochemistry outcomes were missing in 11.81%, and germline testing was performed in 76.30% of eligible patients. In 7 studies, including 6848 CRCs completing all diagnostic stages, germline PV and biallelic somatic MMR inactivation were found in 3.01% and 1.75%, respectively; 0.61% remained unexplained MMRd. Age, completeness, and type of diagnostics affect the percentage of MMR PV and unexplained MMRd percentages. Complete diagnostics explain almost all MMRd CRCs, reducing the amount of subsequent multigene panel testing. This contributes to optimizing testing and surveillance in MMRd CRC patients and relatives.

BIOFILM AND TUMOR: INTERPRETATION OF INTERACTION AND TREATMENT STRATEGIES. Review

Relevance. Treatment of solid tumors and biofilm-derived infections face a common problem: drugs often fail to reach and kill cancer cells and microbial pathogens because of local microenvironment heterogeneities. There are remarkable challenges for current and prospective anticancer and antibiofilm agents to target and maintain activity in the microenvironments where cancer cells and microbial pathogens survive and cause the onset of disease. Bacterial infections in cancer formation will increase in the coming years. Collection of approaches such as ROS modulation in cells, the tumor is promoted by microbe’s inflammation can be a strategy to target cancer and bacteria. Besides that, bacteria may take the advantage of oxygen tension and permissive carbon sources, therefore the tumor microenvironment (TM) becomes a potential refuge for bacteria. It is noteworthy that the relationship between cancer and bacteria is intertwined.&#x0D; Objective: To analyze similarities between biofilm and tumor milieu that is produced against stress conditions and heterogeneous microenvironment for a combination of approaches the bacteriotherapy with chemotherapy which can help in defeating the tumor heterogeneity accompanied with malignancy, drug-resistance, and metastasis.&#x0D; Method: An analytical review of the literature on keywords from the scientometric databases PubMed, Wiley.&#x0D; Results: Bacteria evade antimicrobial treatment is mainly due to persistence that has become dormant during the stationary phase and tolerance. Drug-tolerant persisters and cellular dormancy are crucial in the development of cancer, especially in understanding the development of metastases as a late relapse. Biofilms are formed by groups of cells in different states, growing or non-growing and metabolically active or inactive in variable fractions, depending on maturity and on chemical gradients (O2 and nutrients) of the biofilms producing physiological heterogeneity. Heterogeneity in the microenvironment of cancer can be described as a non-cell autonomous driver of cancer cell diversity; in a highly diverse microenvironment, different cellular phenotypes may be selected for or against in different regions of the tumor. Hypoxia, oxidative stress, and inflammation have been identified as positive regulators of metastatic potential, drug resistance, and tumorigenic properties in cancer. It is proven that, Escherichia coli (E. coli) and life-threatening infectious pathogens such as Staphylococcus aureus (SA) and Mycobacterium tuberculosis (Mtb) are noticeably sensitive to alterations in the intracellular oxidative environment. An alternative emerging paradigm is that many cancers may be promoted by commensal microbiota, either by translocation and adherence of microbes to cancer cells or by the distant release of inflammation-activating microbial metabolites. Microbial factors such as F. nucleatum, B. fragilis, and Enterobacteriaceae members may contribute to disease onset in patients with a hereditary form of colorectal cancer (CRC); familial adenomatous polyposis (FAP). These findings are linked with the creation of new biomarkers and therapy for identifying and treating biofilm-associated cancers. Currently, about 20% of neoplasms globally can be caused by infections, with approximately 1.2 million cases annually. Several antineoplastic drugs that exhibited activity against S. mutans, including tamoxifen, doxorubicin, and ponatinib, also possessed activity against other Gram-positive bacteria. Drug repurposing, also known as repositioning, has gained momentum, mostly due to its advantages over de novo drug discovery, including reduced risk to patients due to previously documented clinical trials, lower drug development costs, and faster benchtop-to-clinic transition. Although many bacteria are carcinogens and tumor promoters, some have shown great potential towards cancer therapy. Several species of bacteria have shown an impressive power to penetrate and colonize solid tumors, which has mainly led to neoplasm slower growth and tumor clearance. Different strains of Clostridia, Lactococcus, Bifidobacteria, Shigella, Vibrio, Listeria, Escherichia, and Salmonella have been evaluated against cancer in animal models. &#x0D; Conclusion. Cancer is a multifactorial disease and the use of bacteria for cancer therapy as an immunostimulatory agent or as a vector for carrying the therapeutic cargo is a promising treatment method. Therefore, the world has turned to an alternative solution, which is the use of genetically engineered microorganisms; thus, the use of living bacteria targeting cancerous cells is the unique option to overcome these challenges. Bacterial therapies, whether used alone or combination with chemotherapy, give a positive effect to treat multiple conditions of cancer.

Antioxidants Promote Intestinal Tumor Progression in Mice.

Dietary antioxidants and supplements are widely used to protect against cancer, even though it is now clear that antioxidants can promote tumor progression by helping cancer cells to overcome barriers of oxidative stress. Although recent studies have, in great detail, explored the role of antioxidants in lung and skin tumors driven by RAS and RAF mutations, little is known about the impact of antioxidant supplementation on other cancers, including Wnt-driven tumors originating from the gut. Here, we show that supplementation with the antioxidants N-acetylcysteine (NAC) and vitamin E promotes intestinal tumor progression in the ApcMin mouse model for familial adenomatous polyposis, a hereditary form of colorectal cancer, driven by Wnt signaling. Both antioxidants increased tumor size in early neoplasias and tumor grades in more advanced lesions without any impact on tumor initiation. Importantly, NAC treatment accelerated tumor progression at plasma concentrations comparable to those obtained in human subjects after prescription doses of the drug. These results demonstrate that antioxidants play an important role in the progression of intestinal tumors, which may have implications for patients with or predisposed to colorectal cancer.

A clinical case of a hereditary form of colorectal cancer associated with a CHEK2 gene defect

The article describes a clinical case of colorectal cancer with a positive family history. In the course of a molecular genetic study by NGS sequencing, a germinal c.1607delC mutation was detected in exon 15 of the CHEK2 gene (NM_007194.4). According to ClinVar, this option has uncertain clinical significance. The article provides literature data on cases of carriage of CHEK2 gene mutations. More careful monitoring of carriers of pathogenic variants in the CHEK2 gene from families with multiple manifestations of colorectal cancer is now recommended.

Abstract 1103: Aspirin reduces the incidence of metastasis in a preclinical study of Braf mutant colorectal cancer

Abstract Background. Aspirin is a well-studied chemopreventive agent for the prevention of conventional colorectal adenomas and cancer. Post hoc analyses of cardiovascular prevention trials demonstrate a long-term reduction in colorectal cancer incidence and mortality with aspirin treatment. Randomized controlled trials have shown a long-term benefit for reducing colorectal cancer incidence in patients with Lynch Syndrome, a form of hereditary colorectal cancer. These findings have led to the recommendation of aspirin as a chemopreventive for colorectal cancer by the U.S. Preventive Services Task Force and Cancer Council Australia. However, future research questions have noted a lack of knowledge of the differential benefits of aspirin in preventing sessile serrated lesions versus conventional adenomas and cancer. In our study, we hypothesized that aspirin will be an effective long-term treatment for the prevention of colorectal cancer resulting from sessile serrated lesions. We aimed to investigate this in a preclinical study utilizing a murine model of Braf mutant serrated neoplasia with a primary end-point investigating cancer incidence. Methods. BrafV637E/+/Villin-CreERT2/+ mice were injected with tamoxifen (i.p. 75mg/kg) at 2 weeks of age to activate the Braf mutation within the intestine, then commenced on an aspirin-supplemented (n=78) or control standard (n=83) diet at wean. Aspirin was supplemented into the diet and provided ad libitum, at a human equivalent dose of 80-120mg per day, until sacrifice at 14 months. The gastrointestinal tract was excised and evaluated for the presence of carcinoma. In addition, the peritoneal and thoracic cavities were inspected for metastatic disease. A gastrointestinal pathologist (CL) assessed all histology sections. Results. At sacrifice, 14 months post induction of mutant Braf, all mice developed murine serrated lesions reminiscent of human sessile serrated lesions. We observed a carcinoma incidence of 31% (26/83) of which 35% (9/26) had metastasized to the liver or peritoneal cavity. When mice were treated with an aspirin-supplemented diet there was no significant reduction in carcinoma incidence (22/78, 28%, P = 0.7315). However, there was a significant reduction in the incidence of metastasis (1/22, 5%, P = 0.0134). Mice in the control group had lesions of a significantly greater size when compared to aspirin treated mice (P=0.0032). Conclusions. Aspirin resulted in a 7-fold decrease in metastases. This study demonstrates that the benefit of aspirin in preventing Braf mutant serrated neoplasia occurs at the carcinoma-metastasis phase of colorectal carcinogenesis. This could have potential clinical benefit in reducing recurrence and mortality. Citation Format: Alexandra Kane, Cheng Liu, Lochlan Fennell, Diane McKeone, Jennifer Borowsky, Barbara Leggett, Vicki Whitehall. Aspirin reduces the incidence of metastasis in a preclinical study of Braf mutant colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1103.

Hereditary Nonpolyposis Colorectal Cancer (HNPCC): From Diagnosis to Surgical Management of the Main Hereditary Form of Colorectal Cancer: A Review

Hereditary Nonpolyposis Colorectal Cancer (HNPCC): From Diagnosis to Surgical Management of the Main Hereditary Form of Colorectal Cancer: A Review

Hereditary Nonpolyposis Colorectal Cancer HNPCC: From Diagnosis to Surgical Management of the Main Hereditary Form of Colorectal Cancer: A Review

Colorectal cancer (CRC) is the third most common cancer worldwide, the 5% of CRC are hereditary. Among hereditary forms of CRC the most frequent is Hereditary Nonpolyposis Colorectal Cancer (HNPCC). HNPCC is an autosomal dominant genetic disease. Molecular basis of HNPCC are linked to genetic alterations, involving several mismatch repair (MMR) genes. Diagnosis of HNPCC is frequently difficult: HNPCC diagnosis process starts from family medical history and genetic counselling and continue with molecular diagnosis and genetic tests which often identify MMR genes mutation. In HNPCC the role of screening is irreplaceable for prevention and early diagnosis of CRC and extracolic cancer, such as endometrium, ovary, urothelium, stomach, small bowel, pancreas, brain, biliary ducts neoplasms. Surgical management of HNPCC is significantly different between colonic and rectal cancer. The main problem in surgical approach for HNPCC patients is related to the possibility of developing metachronous colorectal cancer. The choice is always between extensive and segmental resection. The aim of this study is to give some practical indications to surgeons for the management of HNPCC patients.

Incorporating Colorectal Cancer Genetic Risk Assessment into Gastroenterology Practice.

Decades have passed since the underlying molecular etiologies of the most common hereditary forms of colorectal cancer (CRC), Lynch syndrome, and familial adenomatous polyposis (FAP) were first described. With the advent of next-generation sequencing (NGS) panels, the landscape of hereditary CRC testing has changed dramatically. We review available screening strategies, novel CRC predisposition genes, and challenges and opportunities in this field. Improved sensitivity and availability of NGS panel testing have greatly expanded our understanding regarding the number of CRC syndromes and their phenotypic expression. A variety of screening strategies are available to identify heritable CRC syndromes, potentially decreasing morbidity and mortality in this population. However, these screening strategies remain imperfect and present challenges regarding their implementation in clinical practice. Screening strategies include universal screening of CRC tumors for Lynch syndrome, clinical prediction algorithms, and risk assessment questionnaires. Additionally, there remains a gap in our understanding of the clinical implications of novel gene mutations of variable penetrance and unexpected NGS panel test results. Incorporation of single nucleotide polymorphisms (SNPs) may help to further refine cancer risk assessment, and the clinical introduction of RNA analysis may allow us to clarify variants of unknown significance (VUSs) and identify deep intronic mutations that would otherwise be missed. Recognition of genetic predisposition to CRC is critical for the practicing gastroenterologist. The evolving field of cancer genetics offers great challenges and opportunities for improved CRC management.

Abstract 655: Clinicopathological and genetic features of colorectal cancer in Algerian patients

Abstract Background Colorectal carcinoma is the third most common form of cancer worldwide. It is the second most common cancer in men and women in Algeria.The aim of this study was to determine clinicopathological and genetic features of colorectal cancer in Algerian patients. For the genetic study, we focused on the two major forms of hereditary colorectal cancer, Familial Adenomatous Polyposis (FAP) and Lynch Syndrome (LS), respectively. Materials and Methods The study population included 366 patients diagnosed with colorectal cancer (CRC). Colorectal carcinoma was diagnosed between January 2017 to March 2018. Clinical and tumor data: age at diagnosis, site of tumor and TNM stage were collected from the medical records of the patients. We screened by PCR-direct sequencing exon 15 of APC gene in 30 patients with a strong family history of classic FAP. 30 patients with Lynch syndrome who fulfilled Amsterdam criteria were screened by PCR- direct sequencing for germline mutations in the MMR genes: MLH1 (exons 9,10,13,16), MSH2 (exons 5,6,7,12) and MSH6 (exon 4). Two FAP patients and two LS patients were screened by NGS using a cancer panel of 30 hereditary cancer genes (Color Genomics, California, USA). Results In this retrospective study, there were 183 women (50%) and 183 men (50%).The median age at diagnosis cancer was 58 years old. The highest proportions of CRC were observed for the age groups 60-69, 50-59 and 40-49 years, 25.4%, 23.49%, 20.49% respectively. We noticed that colorectal tumors were not uniformly distributed through the large bowel. Rectum was the most common site (26.8%) followed by right colon (20.5%), sigmoid colon (18.9%) left colon (13.7%) and caecum (7.4%). Our results showed that 75.95% of the CRC patients were diagnosed at TNM stage II (9.02%), stage III (48.63%) and stage IV (18.31%), respectively. The analysis of DNA samples of FAP patients revealed that 6 patients carried pathogenic variants in APC gene. 3 distinct pathogenic variants: c.1605dupT ( one patient), c.3784delT (2 related patients), and c.3927_3931delAAAGA (3 unrelated patients) were identified in APC gene. Moreover, three distinct germline mutations: c.55_63delATCGCGGCGinsT in exon 1 of MLH1 (one patient), c.1165C&amp;gt;T in exon 7 of MSH2 ( one patient) and the Newfoundland mutation c.942 +3A&amp;gt;T in exon 5 of MSH2 (3 unrelated patients) were detected in 5 Lynch syndrome families.The APC c.1605dupT and c.3784delT and the MLH1 c.55_63delATCGCGGCGinsT new variants have never been reported in LOVD, UMD and ClinVar databases and could be specific of Algerian FAP patients and Lynch syndrome patients, respectively. Haplotype analysis of the APC c.3927_3931delAAAGA and the c.942+3A&amp;gt;T MSH2 variants will establish their genetic origin in Algeria. Conclusions The accumulative knowledge about clinicopathological and genetic characteristics of colorectal cancer in Algerian patients will impact on clinical management in the areas of both prevention and treatment. Citation Format: Farid Cherbal, Asma Lamia Boumehdi, Feriel Khider, Fatma Narimane Nouredine, Karim Layaida, Hassen Mahfouf, Mustapha Maaoui. Clinicopathological and genetic features of colorectal cancer in Algerian patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 655.

Gene mapping and molecular analysis of hereditarynon-polyposis colorectal cancer (Lynch Syndrome)using systems biological approaches.

Hereditary non-polyposis colorectal cancer (HNPCC) also known as Lynch Syndrome (LS), is a hereditary form of colorectal cancer (CRC). LSis caused by mutations in the mismatch repair (MMR) genes, mostly in MLH1, MSH2, MSH6 and PMS2. Identification of these gene mutations is essential to diagnose CRC, especially at a young age to increase the survival rate. Using open target platform, we have performed genetic association studies to analyze the different genes involved in the LS and to obtain target for disease evidence. We have also analyzed upstream regulators as target molecules in the data sets. We discovered that MLH1, MSH2, MSH6, PMS2, MLH3, EPCAM, TGFBR2, FBXO11 and PRSS58 were showing most association in LS. Our findings may further enhance the understanding of the hereditaryform of CRC.

Implementation of a Systematic Tumor Screening Program for Lynch Syndrome in an Integrated Health Care Setting.

A subset of colorectal cancer (CRC) cases are attributable to Lynch syndrome (LS), a hereditary form of CRC. Effective evaluation for LS can be done on CRC tumors to guide diagnostic testing. Increased diagnosis of LS allows for surveillance and risk reduction, which can mitigate CRC-related burden and prevent cancer-related deaths. We evaluated participation in LS screening among newly diagnosed adult CRC patients. Some cases were referred for genetics evaluation prior to study recruitment (selective screening). Those not referred directly were randomized to the intervention or control (usual care) arms. Control cases were observed for one year, then given information about LS screening. Patients who declined participation were followed through the medical record. Of 601 cases of CRC, 194 (32%) enrolled in our study and were offered LS screening, 43 (7%) were followed as a control group, 148 (25%) declined participation and 216 (36%) were ineligible [63 (10%) of which received prior selective screening]. Six and nine cases of LS were identified through the intervention and selective screening groups, respectively. Overall, a higher proportion of PMS2 variants were identified in the intervention (3/6, 50%) versus selective screening groups (2/9, 22%) (not statistically significant). Eighty-eight percent and 23% of intervention and control patients, respectively, received LS screening. No control patients were found to have LS. Systems-based approaches are needed to ensure we fully identify LS cases. The proportion of LS cases from this program was 4% of newly diagnosed cases of CRC, similar to other programs.

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.

Наследственный колоректальный рак: генетика и скрининг

Aim of review. To present the data on main forms of hereditary colorectal cancer (CRC) and to discuss issues of its diagnostics, genetic testing and patient management. Summary. CRC is one of the most widespread oncologic diseases and takes the leading positions for morbidity and mortality in the pattern of neoplastic diseases in Russia. In 30% of cases disease development is associated to genetic predisposition, however only 5% of all CRC cases are linked to established hereditary syndromes, such as Lynch syndrome (hereditary non-polyposis colorectal cancer), family adenomatous polyposis, MUTYH-associated polyposis, juvenile polyposis, hereditary mixed polyposis syndrome, Peutz-Jeghers syndrome and serrated polyposis syndrome. The current review presents clinical and genetic features of two basic colorectal hereditary syndromes - Lynch syndrome and family adenomatous polyposis. Conclusion. Both clinical and molecular genetic investigations of hereditary CRC forms make possible individual comprehensive approach for diagnosis verification, evaluation of cancer risk, early diagnostics, treatment and prevention for decrease of morbidity and mortality.

Next Generation Sequencing in Molecular Diagnosis of Lynch Syndrome - a Pilot Study Using New Stratification Criteria.

The development of the new technologies such as the next-generation sequencing (NGS) makes more accessible the diagnosis of genetically heterogeneous diseases such as Lynch syndrome (LS). LS is one of the most common hereditary form of colorectal cancer. This autosomal dominant inherited disorder is caused by deleterious germline mutations in one of the mismatch repair (MMR) genes - MLH1, MSH2, MSH6 or PMS2, or the deletion in the EPCAM gene. These mutations eventually result in microsatellite instability (MSI), which can be easily tested in tumor tissue. According to the actual recommendations, all patients with CRC that are suspect to have LS, should be offered the MSI testing. When the MSI is positive, these patients should be recommended to genetic counseling. Here we report a pilot study about the application of NGS in the LS diagnosis in patients considered to have sporadic colorectal cancer. The inclusion criteria for the NGS testing were MSI positivity, BRAF V600E and MHL1 methylation negativity. We have used 5 gene amplicon based massive parallel sequencing on MiSeq platform. In one patient, we have identified a new pathogenic mutation in the exon 4 of the MSH6 gene that was previously not described in ClinVar, Human Gene Mutation Database, Ensembl and InSight databases. This mutation was confirmed by the Sanger method. We have shown that the implementation of new criteria for colorectal patients screening are important in clinical praxis and the NGS gene panel testing is suitable for routine laboratory settings.

Incomplete Segregation of MSH6 Frameshift Variants with Phenotype of Lynch Syndrome.

Lynch syndrome (LS), the most frequent form of hereditary colorectal cancer, involves mutations in mismatch repair genes. The aim of this study was to identify mutations in MSH6 from 97 subjects negative for mutations in MLH1 and MSH2. By direct sequencing, we identified 27 MSH6 variants, of which, nine were novel. To verify the pathogenicity of these novel variants, we performed in silico and segregation analyses. Three novel variants were predicted by in silico analysis as damaging mutations and segregated with the disease phenotype; while a novel frameshift deletion variant that was predicted to yield a premature stop codon did not segregate with the LS phenotype in three of four cases in the family. Interestingly, another frame-shift variant identified in this study, already described in the literature, also did not segregate with the LS phenotype in one of two affected subjects in the family. In all affected subjects of both families, no mutation was detected in other MMR genes. Therefore, it is expected that within these families, other genetic factors contribute to the disease either alone or in combination with MSH6 variants. We conclude that caution should be exercised in counseling for MSH6-associated LS family members.

Abstract C06: Implementation of Universal Colorectal Cancer Screening for Lynch Syndrome: A Population-Based Study

Abstract Introduction: Colorectal cancer (CRC) is the leading cause of cancer death in Puerto Rico and the third one among US Hispanics. Up to 2-4% of colorectal cancer cases are caused by germline mutation in at least one of these four DNA mismatch repair (MMR) genes: MLH1, MSH2, MSH6, and PMS2. Mutations in these genes cause Lynch Syndrome (LS), the most common hereditary form of CRC. Immunohistochemistry (IHC) tests for the presence of MMR proteins and microsatellite instability (MSI) analysis is often performed on the tumor of CRC cases to screen for LS and as markers for prognosis. Universal screening of CRC for LS has been recommended by the National Comprehensive Cancer Network (NCCN) since 2014. Objective: The purpose of this study was to determine the prevalence of positive LS-screening test as determined by absence of MMR proteins in CRC since the implementation of universal tumor screening for LS in the largest private pathology laboratory in Puerto Rico. Methods: We collected the data from all CRC cases performed at Hato Rey Pathology Laboratories from September 2014 to December 2015. Pathologies performed where collected from 11 hospitals that cover the island of Puerto Rico. The data collected included results of IHC and MSI analysis as well as tumor location, gender, age, date reported and hospital. Results: A total of 317 CRC tumors were evaluated for LS-screening; with a mean age of 66 years, and 54.3% were males. IHC analysis was performed in 288 cases and of these, 11.1% demonstrated absence of one or more of the MMR proteins, compatible with a positive screening test for LS. There were 21 cases that had only MSI analysis performed and they were all reported as microsatellite stable. Conclusion: This is the first evaluation of a systematic program for Universal CRC screening for LS in Puerto Rico. Our data is consistent with results from other studies of US-Hispanics where approximately 10% of individuals of Hispanic origin with CRC have MSI. The observed prevalence of absence of MMR-proteins in our study supports universal screening of LS among Hispanics in accordance with NCCN guidelines. Citation Format: Isabel Sierra, Yaritza Diaz-Algorri, Valerie Maldonado, Kimberly Alicea, Kathia Rosado, Marcia Cruz-Correa. Implementation of Universal Colorectal Cancer Screening for Lynch Syndrome: A Population-Based Study. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr C06.

Detecting APC Gene Mutations in Familial Adenomatous Polyposis (FAP).

Hereditary forms of colorectal cancer (CRC) account for up to 5% of total cases. Familial adenomatous polyposis (FAP) is an autosomal dominant condition affecting nearly 1 in 5000 people and accounts for only about 1% of all CRCs. It is characterized by the progressive development of hundreds to thousands of adenomatous colon polyps. The gene associated with FAP (APC) contains 15 coding exons. The mutation spectrum of the APC gene is broad in that 87% of causative mutations are point mutations (including other sequence variants) and around 10% to 15% are intragenic deletions and duplications. The strategy for molecular diagnostic testing for FAP involves initial full sequence analysis of APC for sequence variants followed by screening for deletion/duplications using microarray-based comparative genomic hybridization (array CGH) or Multiplex Ligation-dependent Probe Amplification (MLPA). Recently, next generation sequencing (NGS)-based targeted gene analysis has become clinically available for detection of point mutations and other sequence variants. This unit discusses detailed protocols for an NGS-based sequencing assay, PCR-based Sanger sequencing, and array CGH. © 2017 by John Wiley & Sons, Inc.