Diagnosis Of Hereditary Nonpolyposis Colorectal Cancer Research Articles

Descriptive Statistics for Patients with Glioblastoma Associated with Germline Mismatch Repair Gene Mutation

<h3>Purpose/Objective(s)</h3> Hereditary Nonpolyposis Colorectal Cancer (HNPCC), also known as Lynch Syndrome, is a genetic mismatch repair mutation associated with increased risk for development of glioblastoma (GBM). There is a paucity of data describing the clinical outcomes of GBM patients with HNPCC. We aim to describe tumor characteristics, treatment patterns, and outcomes. <h3>Materials/Methods</h3> IRB approved retrospective review of consecutive patients with a diagnosis of both HNPCC and GBM at a single institution. <h3>Results</h3> Nine patients with a diagnosis of HNPCC and GBM were treated at a single institution from 2001-2022. Six patients were male. Median age at GBM diagnosis was 61 (range 21-84). Median follow up from the time of GBM diagnosis was 7.83 months. Eight patients had prior malignancies: n=7 with colon adenocarcinoma, n=1 with Burkitt lymphoma. Two patients had active synchronous cancers with GBM. The most common presenting symptoms were facial droop (n=3) and cognitive changes (n=2). Others include headache, gait change, visual field defect, and seizures with n=1 each. All patients underwent surgery: n=2 gross total resection, n=4 subtotal resection, and n=3 biopsy alone. There were 3 temporal lobe, 3 parietal lobe, 2 frontal lobe, and 1 frontoparietal lobe tumors. Two patients had multifocal disease at diagnosis. One patient had a giant cell variant GBM. Seven patients had MSH6 mutations and 2 had MSH2 mutations. Two patients progressed rapidly after surgery and were unable to receive RT. Seven patients received adjuvant radiation therapy (RT): n=5 received concurrent TMZ- 1 with concurrent bevacizumab, 5-fluorouracil, and leucovorin due to synchronous metastatic colon cancer, 1 received no chemotherapy. The most common dose and fractionation schedules were 60 Gy in 30 fractions (fx) (n=3), 40.05 Gy in 15 fx (n=3), and n=1 received 30 Gy in 10 fx due to poor performance status and large tumor volume. One patient received proton therapy for active MS, n=8 received IMRT. Two patients initiated tumor treating fields following RT completion. The median time to progression after RT was 3.35 months, and all progressed within the radiation field. Median survival from diagnosis was 6.5 months (range 1.2-15.5). No patients received immune checkpoint inhibitors. One patient was alive at the time of data collection. Seven died due to GBM progression, and n=1 died from progression of a synchronous malignancy. <h3>Conclusion</h3> In this small series, patients with mismatch repair mutation associated glioblastoma had especially poor outcomes and a rapidly progressive disease course.

Copy Number Variants Captured by the Array Comparative Genomic Hybridization in a Cohort of Patients Affected with Hereditary Colorectal Cancer in Sri Lanka: The First CNV Analysis Study of the Hereditary Colorectal Cancer in the Sri Lankan Population

Introduction:Hereditary non-polyposis colorectal cancer (HNPCC), is an autosomal dominant disorder characterized by the development of multiple cancer types. Molecular diagnosis of HNPCC requires the precise identification of pathogenic germline variants in DNA mismatch repair (MMR) genes. Next Generation Sequencing (NGS) is now the gold standard test in practice, to identify these variants. However, large genomic rearrangements (LGR) in cancer predisposing genes (CPGs) are missed by NGS. This may lead to underestimation of the frequency of the variants, misleading the genetic diagnosis and delaying intervention in high risk individuals. Hence this study was aimed at identifying the presence of large genomic alterations that could explain the missing heritable risk of colon cancer in affected patients with family history strongly suggestive of hereditary colorectal cancer in Sri Lanka. Methods:A cohort of six patients affected with hereditary colorectal cancer who tested negative for pathogenic variants in next generation sequencing studies was investigated using Sure Print G3 Human CGH 4x180K microarray platform. Agilent Genomic-Workbench-v7.0.4.0 software was used to identify the Copy Number Variants (CNV). Four healthy individuals (>55years) were used as controls. Annotations of the CNV regions which were observed were done using the database of Genomic Variants. Results:We identified 150 CNVs including regions of both genomic gains and losses in the patient cohort. There was no difference in the average number or the average genomic burden of CNVs identified in the patients versus the controls. CNVs were residing on the positions of 1q21.2, 2q37.3, 2p11.2-p11.1, 5q13.2, 6p12.3, 7q31.33, 7p14.1, 14q32.33, 15q11.1-11.2, 16p11.2, 22q11.22, 22q13.1 that were assessed by the array platform used in the study. CNVs in any of the well-known common CPG s or CNVs that reside on or in close proximity to genes corresponding to MMR pathway were not identified. We found several distinct pathways that have previously been identified as having a direct association with the progression of HNPCC. Conclusion:This study shows that CNVs are likely contributors to the colorectal cancer predisposition in a small but significant proportion of patients affected with hereditary colorectal cancer in this cohort. Further studies have to perform to get a better understanding on the contribution of CNVs to the cancer predisposition in this cohort of patients in the Sri Lankan population.

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.

Prevalence and characteristics of hereditary non-polyposis colorectal cancer (HNPCC) syndrome in immigrant Asian colorectal cancer patients

BackgroundThe prevalence of Hereditary Non-Polyposis Colorectal Cancer (HNPCC) is 2 to 5% in the Caucasian population. HNPCC is caused by genomic mutations in DNA mismatch repair genes (MMR), namely MLH1, MSH2, MSH6, PMS2, and EPCAM. A non-hereditary, acquired process of hypermethylation of the MLH1 promoter can also lead to silencing of MLH1 protein expression. Diagnosis of HNPCC in patients with colorectal and other related cancers is important in the clinical treatment and surveillance of related cancers. The prevalence and clinical characteristics of HNPCC in Asian colorectal cancer patients has been reported in small studies and unique features have been suggested.MethodsWe retrospectively reviewed the clinical characteristics of Asian patients who were diagnosed of colon cancer between 1/2002 and 6/2015, and performed IHC for four MMR protein expressions on tumor specimens as a screening test for HNPCC, followed by confirmatory tests of genomic sequencing and hypermethylation analysis.ResultsOne hundred forty-three patients were identified. Thirty-one patients were diagnosed younger than 50 years old, while 112 patients were diagnosed older than 50 years old. Six cases of HNPCC were found with a prevalence of 4.19%. The prevalence in the group of patients diagnosed younger than 50 years old is 16.1%, and that in patients diagnosed older than 50 years old is 0.89%. All patients with HNPCC had family histories of colon or gastric cancer. Tumor locations in the HNPCC patients were predominantly in the descending or sigmoid colon (67%). Half of the HNPCC patients had MSH6 mutations. Hypermethylation of the MLH1 gene was only present in 2.80% of the patients.ConclusionThe prevalence of HNPCC is high in patients younger than 50 years old and extremely low in those older than 50 years old. These results may be useful in the future development of guidelines for HNPCC laboratory screening among Asian patients. The pathological and clinical features of HNPCC in this group of Asian immigrant patients are more similar to those reported on Asian patients in their home countries than to Caucasian patients in Western countries, and will warrant further large-scale evaluation.

Genetic counseling for hereditary cancer

This paper provides an overview of the current approach to genetic counseling for cancer, using hereditary nonpolyposis colorectal cancer (HNPCC) as a prototype. Heretofore, when evaluating the possibility of an HNPCC diagnosis, physicians had to rely exclusively on a detailed family history of cancer in the context of an extended pedigree. Patients in the direct genetic lineage who had one or more first-degree relatives with an HNPCC syndrome cancer were told that they had a 50% likelihood of inheriting the deleterious gene. However, with the discovery of the HNPCC genes (hMSH2, hMLH1, hPMS1, hPMS2), genetic counseling can now provide a more precise determination of a patient's lifetime cancer destiny. Since these DNA findings are new, guidelines for sharing this information with patients remain preliminary. One must be certain that the patient wants to receive DNA information and that he or she is aware of potential discrimination by insurance companies and employers, as well as the possibility of psychological sequelae.

HMSH2 and HMSH6 gene expression profiles in colorectal adenocarcinoma in patients up to 50 years of age.

Lynch syndrome, previously called hereditary non-polyposis colorectal cancer (HNPCC), is a major mortality threat. It is an autosomal dominant disease which is caused by a germline mutation in the DNA mismatch repair (MMR), especially in patients aged up to 50 years. Such mutation more frequently occurs in the hMSH2 gene (38-40%) and less frequently in the hMSH6 gene (14-16%). These mutations, when associated with the patient's lifestyle, may reveal a considerable variability in the disease manifestations, such as the degrees of penetrance and clinical aggressiveness. The aim of this study is to analyze the expression of DNA MMR genes, and correlate this expression with the clinical and anatomopathological findings of the neoplasia in patients aged between 39 and 49 years. A total of 45 patients were included: (48.9%) males and (51.1%) females, and they all underwent resection of a colorectal adenocarcinoma. The tissue microarray technique was used to analyze the relative and absolute expression of hMSH2 and hMSH6. Amsterdam II criteria for the diagnosis of HNPCC were obtained from the data provided by medical records and interviews with patients. hMSH2 and hMSH6 was expressed in all patients, which correlated between each other (RHO=0.669 and p<0.001) but not to age. There is a positive correlation between the expressions of males (RHO=0.673 and p=0.001) and females (RHO=0.006 and p<0.001). It is possible to evaluate the expression of MMR genes in embedded anatomopathological samples. Gene expressions correlated between each other and to the sex of the patients, but no difference in relation to age.

Germline mutation and protein expression analysis of mismatch repair genes MSH6 and PMS2 in Malaysian Lynch syndrome patients

Dear Editor: Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is the most common hereditary form of colorectal cancer (CRC). The diagnosis of HNPCC or Lynch syndrome represents a major challenge because of its genotype and phenotype heterogeneity. Although Amsterdam criteria and Bethesda criteria might be useful for the diagnosis assessment of HNPCC family, there will be clinical situations involving families that may be wholly uninformative for the application of these criteria. The genetic basis of Lynch syndrome has been associated with potentially pathogenic mutations in a group of DNA MMR genes (MLH1 , MSH2 , MSH6 , PMS1 , and PMS2). Germline mutation analysis of DNA MMR genes is the most crucial process for the confirmation of the clinical diagnosis of Lynch syndrome cases. The mutation spectrum of DNA MMR genes appear to be diverse in both distribution and nature of mutations. Although mutation data is available from different parts of the world in varying frequencies, reports on Malaysian patients are scarce. This study was undertaken to unravel the spectrum of germline mutation in DNA MMR genes in Malaysian Lynch syndrome patients. Due to the minor role of germline MSH6 and PMS2 mutations, we adapted the Lynch syndrome detection strategy for the Malaysian population of CRC patients, whereby germline mutations were first sought for MLH1 and MSH2 genes, to be followed byMSH6 and PMS2 genes. The choice about which gene should be tested first was guided by immunohistochemical (IHC) analysis of protein expression of MMR genes. Earlier, we did germlinemutation analysis ofMLH1 and MSH2 genes in 50 Lynch syndrome patients, out of which the data for 34 Lynch syndrome patients has already been reported [1]. In addition to and continuation of the previous report, this report specifically focus on the protein expression profile and germline mutations of MSH6 and PMS2 genes in 50 Malaysian Lynch syndrome suspected patients.

Abstract 335: Mutation analysis of KRAS and BRAF genes in sebaceous lesions and keratoacanthomas sporadic or related to hereditary syndrome

Abstract BACKGROUND: Sebaceous lesions comprises: hyperplasias, adenomas, sebaceomas and carcinomas, which can be sporadic or related to hereditary syndrome. Keratoacanthomas, as sebaceous lesions, can be associated with hereditary cancer, known as Muir-Torre syndrome (MTS), accepted as the presence of those lesions with visceral malignancies, mainly colorectal cancer (CRC). Besides, a subset of MTS shares clinical, pathological and molecular characteristics with hereditary nonpolyposis colorectal cancer (HNPCC). BRAF mutation has already been described in sebaceous hyperplasia but not in CRC in an onset of HNPCC. BRAF oncogene is part of the MAPKinase pathway, as KRAS gene, and both have an important role in cellular proliferation, differentiation and apoptosis. OBJECTIVE: The aim of this study was to evaluate the role of KRAS and BRAF genes in sebaceous lesions and keratoacanthomas in a sporadic setting or related with hereditary syndrome. METHODS: KRAS (codons 12 and 13) and BRAF (V600E) mutations of 52 sebaceous lesions and 42 keratoacanthomas samples was evaluated using Sanger sequencing. 24 (46%) patients had at least one internal malignancy and thus were diagnosed as having MTS. 7 (14%) patients presented clinical or molecular diagnosis of HNPCC. RESULTS: Mutations in KRAS was identified in 7 of 52 cases (14%) of sebaceous lesions and 10 of 42 cases (24%) of keratoacanthomas. BRAF mutation was observed in 2 of 52 cases (4%) of sebaceous lesions and 2 of 42 cases (5%) of Keratoacanthomas. Mutation in both genes occurred in just one sample. There was no statistical significance observed with clinical variables. BRAF mutation was not observed in patients with diagnosis of MTS or HNPCC. CONCLUSION: The results indicate that KRAS and BRAF mutations play a distinct role in carcinogenesis of sebaceous lesions and KRAS a more important event in keratoacanthomas. KRAS mutation was observed in sporadic lesions and also related to hereditary syndrome. However, BRAF mutation was not observed in patients with HNPCC, concordant with observed in CRC with the same origin. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 335. doi:10.1158/1538-7445.AM2011-335

Risk of Colorectal Adenoma and Carcinoma After Colectomy for Colorectal Cancer in Patients Meeting Amsterdam Criteria

To report the risk of metachronous colorectal neoplasia after colectomy for cancer in Hereditary Nonpolyposis Colorectal Cancer (HNPCC) syndrome. Patients meeting Amsterdam criteria for diagnosis of HNPCC have a lifetime colorectal cancer risk approaching 80%, and a metachronous cancer rate of approximately 25%. Therefore, when colon cancer is diagnosed, total rather than segmental colectomy is advocated. However, information about adenoma and carcinoma risk after index surgery is still underreported. A hereditary colorectal cancer database was reviewed for patients meeting Amsterdam criteria who underwent colectomy for cancer. Patient demographics, surgical management, and results of follow-up were recorded. Metachronous colorectal adenoma and carcinoma development were the primary end points. A total of 296 patients (253 with segmental colectomy and 43 with total colectomy/ileorectal anastomosis) were analyzed. Of the 253 segmental colectomy patients, 221 (88%) had postoperative endoscopic surveillance with median follow-up of 104 months. In 74 patients (33%), 256 adenomas were detected, including 140 high-risk adenomas in 48 patients (22%). Fifty-five patients (25%) developed a second colorectal cancer at a median of 69 months after index surgery. Stages of the metachronous cancers were I-16, II-18, III-12, and IV-2. By comparison, 4 of 38 patients (11%) who underwent total colectomy developed subsequent high-risk adenomas and 3 (8%) developed metachronous cancer. Amsterdam patients undergoing partial colectomy have a high rate of metachronous high-risk adenomas and carcinomas. Total colectomy for the index cancer is the procedure of choice. For either surgical option, yearly endoscopic surveillance is essential to remove premalignant adenomas.

Comprehensive genetic analysis of seven large families with mismatch repair proficient colorectal cancer

Approximately 40% of colorectal cancer (CRC) families with a diagnosis of hereditary nonpolyposis CRC on the basis of clinical criteria are not a consequence of mismatch repair (MMR) deficiency. Such families provide supporting evidence for the existence of a hitherto unidentified highly penetrant gene mutation. To gain further understanding of MMR-competent familial colorectal cancer (FCC), we studied seven large families with an unexplained predisposition for CRC to identify genetic regions that could harbor CRC risk factors. First, we conducted a genome-wide linkage scan using 10K single-nucleotide polymorphism (SNP) arrays to search for disease loci. Second, we studied the genomic profiles of the tumors of affected family members to identify commonly altered genomic regions likely to harbor tumor suppressor genes. Finally, we studied the possible role of recently identified low-risk variants in the familial aggregation of CRC in these families. Linkage analysis did not reveal clear regions of linkage to CRC. However, our results provide support linkage to 3q, a region that has previously been linked to CRC susceptibility. Tumor profiling did not reveal any genomic regions commonly targeted in the tumors studied here. Overall, the genomic profiles of the tumors show some resemblance to sporadic CRC, but additional aberrations were also present. Furthermore, the FCC families did not appear to have an enrichment of low-risk CRC susceptibility loci. These data suggest that factors other than a highly penetrant risk factor, such as low or moderate-penetrance risk factors, may explain the increased cancer risk in a subset of familial CRCs.

Preliminary Results of Mismatch Repair Deficiency Screening via Immunohistochemical Staining in Young Asian Colorectal Cancers

Background: The incidence of mismatch repair (MMR) deficiency in young colorectal cancers (CRC) remains unknown in Asians. This preliminary study assessed the clinicopathological features and efficacy of screening for MMR protein deficiency in young Asian CRC patients. Methods: From January 2006 to October 2009, patients under the age of 50 with immunohistochemical (IHC) staining for MMR proteins in resected CRC specimens were retrieved from a prospective computerised database. Results: Eighty unrelated patients comprising predominantly 80% Chinese (n = 64), with median age of diagnosis at 41 years (range 22–50 years) had IHC performed. Twenty-three per cent (n=18) of the patients had abnormal IHC staining. Loss of staining for MLH1, MSH2 and MSH6 proteins were observed in 18%, 2% and 6% of tumours respectively. Of the 15 patients who had abnormal staining of MLH1, three had concomitant equivocal staining for MSH6. One tumour specimen had abnormal staining in all 3 proteins. Multivariate analysis revealed that family history was the only significant predictive factor for defective MMR detection (OR 8.06, 95% CI 1.69–38.35, p=0.002). However if Amsterdam criteria alone were to be used, 72% (n=12) of the cohort would have not been detected for MMR gene defects. Conclusion: The overall burden of germline MMR deficiency in the Singapore population may be as high as 23%. Amsterdam criteria alone are insufficient to detect hereditary non-polyposis colorectal cancer (HNPCC) related patients. The use of IHC staining of at least 3 MMR proteins is a useful screening strategy for HNPCC diagnosis and routine screening of mismatch repair deficiency may be recommended for all young Asian CRC patients.

Hereditary Nonpolyposis Colorectal Cancer (HNPCC): A Pilot Study Assessing Understanding and Attitudes Towards Prenatal Testing

Purpose: Hereditary Nonpolyposis Colorectal Cancer Syndrome (HNPCC) is the most common hereditary cancer syndrome accounting for 2-3% of colorectal cancer (CRC). Patients with HNPCC gene mutations have a 70-80% chance of developing CRC. Little is known about the attitudes of individuals with HNPCC towards prenatal diagnosis. We conducted a pilot study to evaluate HNPCC patients' understanding of their disease and assess their attitudes towards various modalities of prenatal testing. Methods: 12 individuals with HNPCC were educated on the currently available options for prenatal diagnosis of HNPCC including amniocentesis, chorionic villous sampling (CVS), and preimplantation genetic diagnosis (PGD). They were then given a 40-item survey on personal and family history related to HNPCC, demographics, and attitudes toward prenatal testing of their offspring. Results: Nine women and 3 men participated. Mean age at diagnosis was 42.8 years. 83% were Caucasian and 8% African American. 83% were married. 67% had children none of which were yet tested for HNPCC. 83% of the subjects knew there was a 50% risk of their offspring being affected with HNPCC. None were aware of prenatal testing options for HNPCC prior to the study. 100% were of the opinion that prenatal testing options should be discussed and offered to all with a HNPCC gene mutation. 58% would consider undergoing prenatal testing. Of these 100% would consider amniocentesis or PGD and 86% would consider CVS. More subjects were aware of amniocentesis (83%) than PGD or CVS (50%, 25% respectively). 83% felt that all modalities were ethically sound. 50% of the subjects felt that learning the fetus was unaffected with HNPCC was the greatest advantage of PGD. The possibility of complications (58%), or concerns regarding procedure success (33%), seemed to be the greatest disadvantage. 25% of the subjects felt that a HNPCC diagnosis influenced their reproductive decisions. The most important reason against prenatal testing was the difficulty in subsequent decisions making regarding termination. Religious or personal beliefs played little role in decision-making. Conclusion: The majority of HNPCC affected patients surveyed were aware of the autosomal dominant inheritance pattern of HNPCC. All patients felt prenatal testing options should be offered routinely. Though all patients in this study had seen genetic counselors in the past, none were aware of prenatal testing options for their disease prior to this study. This pilot study demonstrates the importance of addressing prenatal testing options in HNPCC patients. Future studies should be conducted to assess if prenatal counseling referral should be required as standard of care in all patients diagnosed with HNPCC.

Microsatellite instability in the evaluation of hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) accounts for most hereditary colorectal cancers. The detection of families with HNPCC enables disease surveillance and clinical management, which significantly reduce morbidity and mortality. Mutations in DNA mismatch repair (MMR) genes underlie HNPCC and cause microsatellite instability (MSI). Although screening for pathogenic mutations in DNA MMR genes is time consuming and costly, MSI-based molecular diagnosis improves HNPCC diagnosis, which was once based on clinical characteristics and family history alone. Patients selected for MSI testing usually fulfill the Bethesda criteria. Tumor MSI status with tissue immunohistochemistry staining directs further genetic evaluation, including sequencing of MMR genes or methylation studies. This review outlines the importance of MSI status in disease diagnosis, prognosis, and treatment.

Comparison of the sensibility and specificity between single-stranded conformation polymorphism and denaturing high-performance liquid chromatography in screening hMSH2 and hMLH1 gene mutations in hereditary non-polyposis colorectal cancer

To compare the sensibility and specificity between single-stranded conformation polymorphism (SSCP) and denaturing high-performance liquid chromatography (DHPLC) in screening hMSH2 and hMLH1 gene mutations for the diagnosis of hereditary non-polyposis colorectal cancer (HNPCC). Seven Chinese HNPCC kindreds were collected. PCR-SSCP and DHPLC were used to screen the coding regions of hMSH2 and hMLH1 genes and the abnormal profiles were sequenced by a 377 DNA sequencer. Seven gene sequence variations of hMSH2 or hMLH1 were found. Among them, 4 variations were not found by SSCP, but by DHPLC. The sensibility of SSCP and DHPLC were 51.6% and 100% respectively, and the specificity were 66.6% and 93.3% respectively. DHPLC has better sensibility and specificity in screening hMSH2 and hMLH1 gene mutation as compared to SSCP. DHPLC is an ideal method in the diagnosis of HNPCC.

Immunohistochemistry versus Microsatellite Instability Testing for Screening Colorectal Cancer Patients at Risk for Hereditary Nonpolyposis Colorectal Cancer Syndrome: Part II. The Utility of Microsatellite Instability Testing

Germline mutations in the mismatch repair genes mutL homolog 1 (MLH1) and mutS homolog 2 (MSH2), MSH6, and postmeiotic segregation increased 2 (PMS2) lead to the development of hereditary nonpolyposis colorectal cancer (HNPCC). Diagnosis of HNPCC relies on the compilation of a thorough family history of cancer, documentation of pathological findings, tumor testing for microsatellite instability (MSI) and immunohistochemistry (IHC), and germline mutation analysis of the suspected genes. As a hallmark of HNPCC, microsatellite instability is widely accepted as a primary method for identifying individuals at risk for HNPCC. It serves as an excellent, easy-to-evaluate marker of mismatch repair deficiency. Recent improvements in MSI testing have significantly enhanced the accuracy and reduced its cost. Proficiency testing for MSI is available, and laboratory-to-laboratory reproducibility of such testing can be easily evaluated. In addition, the combination of microsatellite instability testing, MLH1 promoter methylation analysis, and BRAF (V600E) mutation analysis can distinguish a sporadic colorectal cancer from one associated with HNPCC, helping to avoid costly molecular genetic testing for germline mutations in mismatch repair genes. In this article, we discuss the development of MSI markers used for HNPCC screening and focus on the advantages and disadvantages of MSI testing in screening for HNPCC patients. We conclude that MSI is as sensitive and specific as IHC, given its excellent reproducibility and its potential capability to indicate mutations not be detected by IHC. MSI has been used and will continue to prevail as the primary screening tool for identifying HNPCC patients.

Clinical value of screening hereditary nonpolyposis colorectal cancer in China with protocol recommended by NCCN guidelines

To investigate the effect of the protocol recommended by NCCN-2007 on the diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC) in China. NCCN protocol consists of identifying HNPCC characteristics according to the revised Bethesda Guidelines,genetic counseling with immunohistochemistry and finally genetic testing. Four hundred and nineteen patients diagnosed as colorectal cancer from January 2002 to February 2006 were selected. The hMLH1 and hMSH2 immunostaining were implemented for 90 patients who fulfilled the revised Bethesda Guidelines, in whom 8 patients fulfilling the Amsterdam II (Criteria were classified as group A and the other 82 patients as group B. The frozen tissues were collected from patients who showed loss of hMLH1 or hMSH2 protein expression, then RNA was extracted, and RT-PCR and cDNA sequencing were adopted to detect the germline mutations of hMLH1 and hMSH2. Tumor tissues from 18 patients showed loss of hMLH1 or hMSH2 protein expression (5 patients in group A and 13 in group B). Finally, 21 patients(8 in group A and 13 in group B showed loss expression of MMR protein) were diagnosed as HNPCC, including 2 cases of hMLH1 and 1 case of hMSH2 mutations. These 3 cases with cDNA mutations did not fulfill the Amsterdam II( Criteria, and were finally diagnosed as HNPCC. The protocol recommended by NCCN-2007 offers a useful approach to identify HNPCC patients,and reduces the possibility of missed diagnosis of HNPCC.

Need of new clinical criteria for the identification of genetic Lynch syndrome

Surveillance programs in families with Hereditary Non-Polyposis Colorectal Cancer (HNPCC), which is an autossomal dominant disease, decrease colorectal carcinoma mortality. There are multiple clinical criteria for the identification of these families, mainly: the Amsterdam Criteria (ACI), the modified Amsterdam Criteria (ACII) and the Bethesda Guidelines (BG). To correlate, in families with HNPCC, the clinical criteria with the probability of detecting a germ-line mutation in MLH1, MSH2 and MSH6 mismatch repair genes. We included 92 affected patients belonging to different families. Clinical criteria leading to HNPCC diagnosis were evaluated. Germ-line mutations in MLH1, MSH2 and MSH6 genes were performed by DGGE/MLPA and direct sequencing. Germ-line mutations were detected in 54/92 (59%) families, 30 in MLH1, 23 in MSH2 and 1 in MSH6. Germ-line mutation detection was significantly lower in ACI without age criteria (0%), when compared to: ACI (60%), ACII (62%), ACII without age criteria (67%) and BG (61%). The classic, modified AC and BG allowed the detection of an identical percentage of families with mutation positive HNPCC. The absence of the age criteria in the ACI makes the HNPCC diagnosis highly unlikely. Simpler and uniform criteria should be elaborated, to allow a homogeneous identification of families with HNPCC.

A Prospective, Multicenter, Population-Based Study of BRAF Mutational Analysis for Lynch Syndrome Screening

Mismatch repair (MMR) deficiencies are the hallmark of tumors arising in Lynch syndrome, however, in approximately 15% of sporadic colorectal cancers (CRC) these deficiencies most often are associated with somatic methylation of the MMR gene MLH1. Recently, an oncogenic mutation in the BRAF gene has been involved in sporadic CRC showing MMR deficiencies as a result of MLH1 promoter methylation. The aim of this study was to evaluate the contribution of BRAF V600E mutation analysis in the identification of MSH2/MLH1 gene mutation carriers in newly diagnosed CRC patients. BRAF V600E mutation was analyzed in CRC patients with MMR deficiencies (microsatellite instability and/or lack of MLH1/MSH2 protein expression) in the EPICOLON population-based study. The effectiveness and efficiency of different strategies were evaluated with respect to the presence of MSH2/MLH1 germline mutations. MMR deficiencies were detected in 119 of the 1222 CRC patients with tumors showing either microsatellite instability (n = 111) or loss of protein expression (n = 81). BRAF mutation was detected in 22 (18.5%) of the patients. None of the patients with unambiguous germline mutation had BRAF mutation. Regardless of the strategy used to identify MSH2/MLH1 gene carriers, the introduction of BRAF analysis in these patients slightly improves their effectiveness. The introduction of BRAF mutation analysis as a step before germline genetic testing in patients with MMR deficiencies achieved a significant reduction in costs per mutation detected. Detection of BRAF V600E mutation could simplify and improve the cost effectiveness of genetic testing for hereditary nonpolyposis colorectal cancer, especially in patients whose family history is incomplete or unknown.

Review article: detection and management of hereditary non‐polyposis colorectal cancer (Lynch syndrome)

The most common hereditary colorectal cancer syndrome is hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome. Diagnosis of this syndrome is difficult, because of lack of specific diagnostic features. To discuss the diagnostic criteria and laboratory work up for HNPCC. Furthermore, surveillance programs for HNPCC and treatment of HNPCC associated colorectal cancer are discussed. Current diagnostic criteria, including the Amsterdam II and Bethesda criteria, are suboptimal for the detection of HNPCC. Molecular screening by microsatellite instability (MSI) and immunohistochemistry (IHC) is useful in the diagnosis of HNPCC. Both techniques have a higher sensitivity compared to the Amsterdam II and Bethesda criteria. A combination of both MSI and IHC provides the most optimal selection for mutation analysis. After identification of a mutation in an affected individual, genetic counselling and presymptomatic mutation analysis should be offered to relatives. Furthermore, colonoscopic surveillance should be performed in proven mutation carriers. Identification of HNPCC is a clinical challenge involving many clinicians. Identification of persons at risk can be achieved by a combination of a detailed family history, testing with molecular and mutation analysis.

From Cancer Families to HNPCC: Henry Lynch and the Transformations of Hereditary Cancer, 1975-1999

Hereditary non-polyposis colorectal cancer (HNPCC) helps us understand how medical genetics has changed over the last forty years. The concept of the "cancer family" emerged from the realization that members of some families developed cancer more frequently than members of others, which led to a series of strategies by clinicians in the 1960s to persuade others of this. By the early 1990s molecular genetics had transformed the disease, from one that a few physicians believed ran in families, to one with precise genetic components that researchers generally accepted, and that could be detected through genetic tests. Nevertheless, a diagnosis of HNPCC still requires that the mutated genes be found within a kin group that is generally accepted as a cancer family. Moreover, the "cancer family" construct was crucial in the search for the HNPCC genes. HNPCC's trajectory can be mapped onto important debates about the complex relations between clinical and molecular genetics knowledge and practice.