Hereditary Nonpolyposis Colorectal Cancer Patients Research Articles

Deciding the operation type according to mismatch repair status among hereditary nonpolyposis colorectal cancer patients: should a tailored approach be applied, or does one size fit all?

BackgroundAlthough extended colectomy (EC) was recommended for HNPCC patients, previous studies did not show significantly improved overall survival. Immunohistochemical (IHC) stain of mismatch repair (MMR) gene protein expression is now a feasible and reliable test clinically. Therefore, we tried to investigate whether we could use MMR IHC stain to select operation types in HNPCC patients.Patients and methodsBetween 1995 and 2013, 186 HNPCC patients were collected. Status of MMR protein expression, perioperative clinic-pathological variables and post-operative follow up status were analyzed by multivariate analyses.ResultsSixty-five percent (121 of 186) patients of these HNPCC patients demonstrated loss of at least one MMR protein. There were several significant differences existing between deficient MMR (dMMR) and proficient MMR (pMMR) subgroups in terms of clinic-pathological characteristics. With the average follow-up duration of 93.9 months, we observed significantly high risk of developing metachronous CRC between SC and EC subgroups (crude rate 8.5% vs. 0%, p = 0.035). However, no significant difference was observed among the presence of extra-colonic tumors (12.4% vs. 5.8%, p = 0.284). The positive and negative prediction rate of metachronous CRC in dMMR subgroup was 12.8 and 87.2% while 1.9 and 98.1% in the pMMR subgroup.Survival outcomes were significantly affected by MMR status and resection types by multivariate analysis. Significantly better OS in dMMR subgroup (HR = 0.479, 95% CI: 0.257–0.894, p = 0.021) comparing with pMMR subgroup was observed. However, significant improved DFS (HR = 0.367, 95% CI: 0.172–.0787, p = 0.010) but not significant for OS (HR = 0.510, 95% CI: 0.219–1.150, p = 0.103) for EC subgroup compared with SC subgroup.Differences existing among different subgroups by combing extent of resection and MMR status. In dMMR subgroup, SC, compared with EC, demonstrated significantly worse DFS by multivariate analyses (HR = 3.526, 95% CI: 1.346–9.236, p = 0.010) but not for OS (HR = 2.387, 95% CI: 0.788–7.229, p = 0.124), however, no significantly differences of OS and DFS in pMMR subgroup between SC and EC were found.ConclusionsSignificantly better overall survival and higher rate of metachronous CRC exist in dMMR subgroup of HNPCC patients comparing with pMMR subgroup. Extended colectomy significantly improved DFS and was thus recommended for dMMR subgroup but not pMMR subgroup of HNPCC patients.

Comprehensive analysis and ACMG‐based classification of CHEK2 variants in hereditary cancer patients

CHEK2 variants are associated with intermediate breast cancer risk, among other cancers. We aimed to comprehensively describe CHEK2 variants in a Spanish hereditary cancer (HC) cohort and adjust the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) guidelines for their classification.First, three CHEK2 frequent variants were screened in a retrospective Hereditary Breast and Ovarian Cancer cohort of 516 patients. After, the whole CHEK2 coding region was analyzed by next-generation sequencing in 1848 prospective patients with HC suspicion. We refined ACMG-AMP criteria and applied different combined rules to classify CHEK2 variants and define risk alleles.We identified 10 CHEK2 null variants, 6 missense variants with discordant interpretation in ClinVar database, and 35 additional variants of unknown significance. Twelve variants were classified as (likely)-pathogenic; two can also be considered "established risk-alleles" and one as "likely risk-allele."The prevalence of (likely)-pathogenic variants in the HC cohort was 0.8% (1.3% in breast cancer patients and 1.0% in hereditary nonpolyposis colorectal cancer patients).Here, we provide ACMG adjustment guidelines to classify CHEK2 variants. We hope that this study would be useful for variant classification of other genes with low effect variants.

Different surgical outcome and follow-up status between dMMR and pMMR colorectal cancer patients who fulfilled with Amsterdam-II criteria

BackgroundAlthough hereditary non-polyposis colorectal cancer (HNPCC) could be subtyped into proficient or deficient mismatch repair gene expression (pMMR or dMMR), distinct clinical features between these two subgroups patients were rarely reported.MethodsWe retrospectively analyzed 175 hereditary non-polyposis colorectal cancer (HNPCC) patients between January 1995 and December 2012. Cox proportional hazards model was used to compare the differences between two subgroups.ResultsSignificant differences of disease free survival (DFS) and overall survival (OS) exist between dMMR and pMMR. In addition to other factors including younger mean age of diagnosis for dMMR patients (48.6 years vs. 54.3 years), operation type (more extended colectomy for dMMR 35.8% vs. 14.5%), tumor location (right colon predominance for dMMR 61.7% vs. 27.3% and more rectum cases for pMMR 41.8% vs. 11.7%), tumor differentiation (more poor differentiation for dMMR 23.3% vs. 9.0%), N staging (more N0 cases for dMMR 70.8% vs. 50.9%), more frequently presence of extra-colonic tumors for dMMR (16.7% vs.1.8%), and lower recurrence rates (9.1% vs.35.3%). Significantly different cumulative incidences of developing metachronous colorectal cancer were observed with 6.18 for pMMR patients and 20.57 person-years for dMMR patients (p < 0.001).ConclusionsDistinct clinicopathological features significantly exist between dMMR and pMMR subtypes patient, MMR status should be consider to tailor operation types and follow up surveillance between these two subgroups patients who all fulfilled with Amsterdam-II criteria.

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.

Frequent Novel Variations Within MSH2 and MLH1 Genes in a Subset of Iranian Families With Hereditary Non-Polyposis Colorectal Cancer Shadi

Abstract- Hereditary non-polyposis colorectal cancer (HNPCC) is the most frequent autosomal dominant predisposition for development of colorectal cancer (CRC) caused by germline defects in mismatch repair (MMR) genes. Current study was aimed to find genetic variations in MSH2 and MLH1 genes and their correlation with the serum levels of Carcinoembryonic Antigen (CEA) in seven Iranian HNPCC families. Seven unrelated Iranian families including 11 HNPCC patients and 7 affected family members were selected. They were initially screened for mutations in exons 7 of MSH2 and exon 15 of MLH1 gene through polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP). Positive PCR results were further analyzed through exon sequencing. Serum CEA level was determined using the ELISA test. PCRSSCP was positive in 8 out of 18 patients (44%) for exons 7 of MSH2 gene, whereas two samples (11%) demonstrated to bear a mutation in exon 15 of the MLH1 gene. Sequencing analysis of both amplified exons in positive and negative samples have confirmed no mutation in negative samples while revealed 5 and 7 novel mutations in exons 7 and 15, respectively. The mean serum concentration of CEA had a significant difference between HNPCC patients and their healthy family members. Our results demonstrated that the PCR-SSCP method has high specificity and sensitivity in the first step of mutation screening of HNPCC families. High frequency of novel alterations found in the current assay may revise the mutation screening of MSH2 and MLH1 genes and abet further assessment of their frequency among individual HNPCC patients.

Extensive colectomy in colorectal cancer and hereditary nonpolyposis colorectal cancer – long-term results

BackgroundColorectal cancer survival is better in hereditary nonpolyposis colorectal cancer patients than in sporadic colorectal cancer patients and even for hereditary nonpolyposis colorectal cancer with colorectal cancer is not consensual that extensive colectomy is preferable to partial colectomy. This study analyzes and compares the long-term results of these two groups of patients submitted to curative subtotal colectomy or total colectomy. MethodsBetween 2002 and 2018, 68 patients with colorectal cancer without familial adenomatous polyposis were submitted to a total or subtotal colectomy in a single tertiary center. The patients were divided in two groups: hereditary nonpolyposis colorectal cancer patients (with Amsterdam criteria) and sporadic colorectal cancer patients (the others). The presence of Amsterdam criteria for hereditary nonpolyposis colorectal cancer and germline mutation for mismatch repair genes was confirmed by clinical records. Results and survival were analyzed following surgery. ResultsWe obtained a sporadic colorectal cancer group with 31 patients and a hereditary nonpolyposis colorectal cancer group with 37 patients. The two groups differ in age but not in gender, tumor stage or surgical morbidity. The overall survival and disease-free survival were good in both groups but even better for hereditary nonpolyposis colorectal cancer group with statistical significance when comparing the two groups. ConclusionTotal or subtotal colectomy for colorectal cancer provides a good survival. These surgical procedures should be considered the first option for colorectal cancer in young hereditary non polyposis colorectal cancer patients. In those cases, they provide good long-term results, avoiding the risk of metachronous colorectal cancer and the surveillance is restricted only to the remaining need for rectum.

The fragile X CGG repeat shows a marked level of instability in hereditary non-polyposis colorectal cancer patients.

The allelic variation of the FMR1 CGG repeat was investigated by small-pool PCR in nonneoplastic peripheral blood leukocytes from HNPCC patients and matched controls for similar CGG repeat lengths. The allelic variation for repeat lengths appears to be roughly twice as frequent in HNPCC patients as in controls, especially when patients are mutated in hMLH1. There are more expansions in HNPCC patients (42%) than in controls (20%) but this difference is statistically borderline. The mean length of expansions relative to the genuine size did not differ in HNPCC patients or controls (respectively 17% and 20% of the constitutional allelic length). The reported data suggest that instability within nonneoplastic cells of a subset of HNPCC patients might be one mechanism for transition from normal to the premutation range of the FMR1 CGG repeat.

Screening for susceptibility genes in hereditary non-polyposis colorectal cancer.

In the present study, hereditary non-polyposis colorectal cancer (HNPCC) susceptibility genes were screened for using whole exome sequencing in 3 HNPCC patients from 1 family and using single nucleotide polymorphism (SNP) genotyping assays in 96 other colorectal cancer and control samples. Peripheral blood was obtained from 3 HNPCC patients from 1 family; the proband and the proband's brother and cousin. High-throughput sequencing was performed using whole exome capture technology. Sequences were aligned against the HAPMAP, dbSNP130 and 1,000 Genome Project databases. Reported common variations and synonymous mutations were filtered out. Non-synonymous single nucleotide variants in the 3 HNPCC patients were integrated and the candidate genes were identified. Finally, SNP genotyping was performed for the genes in 96 peripheral blood samples. In total, 60.4 Gb of data was retrieved from the 3 HNPCC patients using whole exome capture technology. Subsequently, according to certain screening criteria, 15 candidate genes were identified. Among the 96 samples that had been SNP genotyped, 92 were successfully genotyped for 15 gene loci, while genotyping for HTRA1 failed in 4 sporadic colorectal cancer patient samples. In 12 control subjects and 81 sporadic colorectal cancer patients, genotypes at 13 loci were wild-type, namely DDX20, ZFYVE26, PIK3R3, SLC26A8, ZEB2, TP53INP1, SLC11A1, LRBA, CEBPZ, ETAA1, SEMA3G, IFRD2 and FAT1. The CEP290 genotype was mutant in 1 sporadic colorectal cancer patient and was wild-type in all other subjects. A total of 5 of the 12 control subjects and 30 of the 81 sporadic colorectal cancer patients had a mutant HTRA1 genotype. In all 3 HNPCC patients, the same mutant genotypes were identified at all 15 gene loci. Overall, 13 potential susceptibility genes for HNPCC were identified, namely DDX20, ZFYVE26, PIK3R3, SLC26A8, ZEB2, TP53INP1, SLC11A1, LRBA, CEBPZ, ETAA1, SEMA3G, IFRD2 and FAT1.

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.

Simplified microsatellite instability detection protocol provides equivalent sensitivity to robust detection strategies in Lynch syndrome patients.

Objective: Germline mutations in mismatch repair (MMR) genes cause Lynch syndrome (LS). LS is an inherited disease, and an important consequence of MMR deficiency is microsatellite instability (MSI) phenotype. MSI phenotype influences the efficacy of 5 fluorouracil (5-FU) chemotherapy. Reproducible, cost effective, and easy to perform laboratory tests are required to include MSI detection in routine laboratory practice. Evaluation of CAT25 as monomorphic short tandem repeat sequence enables CAT25 to be an efficient screening tool among hereditary nonpolyposis colorectal cancer (HNPCC) patients compared with other methods used currently.Methods: Based on Amsterdam II criteria, 31 patients in 31 families were shortlisted from a total number of 1,659 colorectal cancer patients. MSI status was examined in these patients using CAT25 and a commercially available Promega MSI five-marker-based detection system as well as immunohistochemical (IHC) staining of four important MMR proteins. Patients were scored as high microsatellite instable (MSI-H), low (MSI-L), or stable (MSS). MSI status determined by CAT25 single mononucleotide marker was compared with that of five mononucleotide markers, Promega commercial kit, and IHC method.Results: MMR protein deficiency was observed on 7/31 probands using IHC methodology and 6/31 categorized as MSI-H using commercial kit or CAT25 single marker. The sensitivity and specificity of the CAT25 single marker were the same as those detected by five-marker Promega commercial kit in our patients.Conclusions: Based on our results, the performance of the CAT25 single mononucleotide marker for MSI status determination in our HNPCC patients is the same as that of the five-marker-based commercial kit.

Association between Mismatch-repair Genetic variation and the Risk of Multiple Primary Cancers: A Meta-Analysis.

Microsatellites instability (MSI) is a risk factor for multiple primary cancers (MPCs). However, a variety of studies focused on the risk in the hereditary non-polyposis colorectal cancer (HNPCC) not the sporadic colorectal cancer (CRC) patients. The aim of this meta-analysis was to comprehensive overview and quantitative summary the association between MSI and risk of MPCs. A comprehensive literature search in MEDLINE, EMBASE, Web of science, ScienceDirect, Weily and OVID was conducted. Up to May 2016, we identified 22 observational studies. We calculated the summary relative risk (RR) for the risk of MPCs in MSI patients compared with microsatellites stability (MSS) patients using fixed- or random-effects models. The RR of the association between mismatch-repair gene (MMR) genotype and MPCs was 2.59 (95% confidence interval [CI], 2.06 to 3.27); the RR was 2.14 (95% CI, 1.78 to 2.57) for sporadic CRC and 5.59 (95% CI, 2.69 to 11.59) for HNPCC for the MSI versus MSS category. The subgroup analyses showed different mutant gene, mutant locus, and mutant level of MMR with different influence on the patients susceptible to MPCs. In addition, MSI genotype increase the risk of MPC was not associated with an apparently specific in regard to site, timing, age and detection method. In conclusion, this meta-analysis indicates that MSI is associated with an increased risk of MPCs both in the HNPCC and sporadic CRC patients. Our findings will form the backbone of the treatment for MSI genotype may be an important valuable strategy for MPCs prevention.

Cytotoxic and targeted therapy for hereditary cancers.

There is a number of drugs demonstrating specific activity towards hereditary cancers. For example, tumors in BRCA1/2 mutation carriers usually arise via somatic inactivation of the remaining BRCA allele, which makes them particularly sensitive to platinum-based drugs, PARP inhibitors (PARPi), mitomycin C, liposomal doxorubicin, etc. There are several molecular assays for BRCA-ness, which permit to reveal BRCA-like phenocopies among sporadic tumors and thus extend clinical indications for the use of BRCA-specific therapies. Retrospective data on high-dose chemotherapy deserve consideration given some unexpected instances of cure from metastatic disease among BRCA1/2-mutated patients. Hereditary non-polyposis colorectal cancer (HNPCC) is characterized by high-level microsatellite instability (MSI-H), increased antigenicity and elevated expression of immunosuppressive molecules. Recent clinical trial demonstrated tumor responses in HNPCC patients treated by the immune checkpoint inhibitor pembrolizumab. There are successful clinical trials on the use of novel targeted agents for the treatment or rare cancer syndromes, e.g. RET inhibitors for hereditary medullary thyroid cancer, mTOR inhibitors for tumors arising in patients with tuberous sclerosis (TSC), and SMO inhibitors for basal-cell nevus syndrome. Germ-line mutation tests will be increasingly used in the future for the choice of the optimal therapy, therefore turnaround time for these laboratory procedures needs to be significantly reduced to ensure proper treatment planning.

Targeted next-generation sequencing of 22 mismatch repair genes identifies Lynch syndrome families.

Causative germline mutations in mismatch repair (MMR) genes can only be identified in ~50% of families with a clinical diagnosis of the inherited colorectal cancer (CRC) syndrome hereditary nonpolyposis colorectal cancer (HNPCC)/Lynch syndrome (LS). Identification of these patients are critical as they are at substantially increased risk of developing multiple primary tumors, mainly colorectal and endometrial cancer (EC), occurring at a young age. This demonstrates the need to develop new and/or more thorough mutation detection approaches. Next‐generation sequencing (NGS) was used to screen 22 genes involved in the DNA MMR pathway in constitutional DNA from 14 HNPCC and 12 sporadic EC patients, plus 2 positive controls. Several softwares were used for analysis and functional annotation. We identified 5 exonic indel variants, 42 exonic nonsynonymous single‐nucleotide variants (SNVs) and 1 intronic variant of significance. Three of these variants were class 5 (pathogenic) or class 4 (likely pathogenic), 5 were class 3 (uncertain clinical relevance) and 40 were classified as variants of unknown clinical significance. In conclusion, we have identified two LS families from the sporadic EC patients, one without a family history of cancer, supporting the notion for universal MMR screening of EC patients. In addition, we have detected three novel class 3 variants in EC cases. We have, in addition discovered a polygenic interaction which is the most likely cause of cancer development in a HNPCC patient that could explain previous inconsistent results reported on an intronic EXO1 variant.

Retrospective analysis of patients with hereditary non- polyposis colorectal cancer (HNPCC)

We performed a one–center cohort retrospective analysis of 1378 non-selected patients operated for colorectal cancer (CRC) in the years 1994 – 2013. For the purpose of this study we divided patients into three subdivisions reflecting their family history of HNPCC–associated cancers among firstand second-degree relatives. On detailed pedigree analysis of the families we identified 59 patients as being affected with HNPCC (4.28%). Compared with other CRC patients our HNPCC subjects were significantly younger at time of diagnosis (median age 51 years, p < 0.05), were more likely to present with right–sided tumors rather than with rectal ones (p < 0.05). Synchronous tumors were found in 45 CRC patients (3.27%), of whom HNPCC subjects were predominant (8.47 vs. 3.03%, p= 0.02). HNPCC patients were also more likely to receive radical resection surgery compared with other CRC patients (93.22% vs. 86.73%). Patients with HNPCC presented with more favorable staging and more frequent mucinous component on histological examination. Overall survival was statistically longer in HNPCC than in other CRC patients (45 vs. 25 months, p =0.01806). Submitted data and our experience in colorectal surgery made us to support conclusion corroborated by literature evidence and regarding fine distinction between HNPCC and sporadic CRC patients.

Characteristics of hereditary nonpolyposis colorectal cancer patients with double primary cancers in endometrium and colorectum

ObjectiveThe hereditary nonpolyposis colorectal cancer is inherited syndrome characterized by the development of cancers in various organ system; these includes colorectum, endometrium, and less frequently, small bowel, stomach, urinary tract, ovaries, and brain. We aimed to investigate the clinicopathologic characteristics of hereditary nonpolyposis colorectal cancer patients who had both endometrial and colorectal cancers.MethodsBetween January 2004 and December 2013, 12 women diagnosed with endometrial and colorectal cancers in a single institution were included in this analysis. For these patients, clinical and molecular findings were analyzed retrospectively.ResultsAll 12 women undertook microsatellite instability analysis, and 9 (75%) were confirmed of having microsatellite instability-high. Among 9 cases with immunohistochemical staining for MLH1 and MSH2, 6 were positive for the loss of mismatch repair protein. Mutational analyses for MLH1 and MSH2 were performed in 3 out of 12 patients; all of them showed germline mutation.ConclusionThis study suggests that there is a genetic background in patients with double primary malignancies in their endometrium and colorectum when analyzed with microsatellite instability studies, immunohistochemistry staining, and mutation studies. This finding supports the necessity of re-defining the high-risk groups in endometrial cancers clinically. This will also help diagnose malignancies in such patients in early stages, as well as counsel other family members.

P33. NK-92 cellular immunotherapy as an alternative to donor derived peripheral blood NK cells

<h3>INTRODUCTION</h3> Hypermethylation of the promoter region of the <i>hMLH1</i> gene is associated with absent expression of MLH1 protein in sporadic colorectal cancers with microsatellite instability (MSI+), and it has been proposed that methylation may be a mechanism of inactivation in Knudson9s hypothesis. The incidence of hypermethylation of the<i>hMLH1</i> promoter in hereditary non-polyposis colorectal cancer (HNPCC) versus MSI+ sporadic colorectal cancer was investigated and compared. <h3>METHODS</h3> DNA was available from 10 HNPCC colorectal cancers (median age 58 years, range 39-67) with germline mutations in <i>hMLH1 </i>and 10 MSI+ sporadic colorectal cancers (mean age 79 years, range 41-85). MSI was determined by amplification of BAT26 and TGF-β RII. The methylation status of the <i>hMLH1</i> promoter was studied by the polymerase chain reaction (PCR) based<i>Hpa</i>II restriction enzyme assay technique. Evidence of allelic loss at <i>hMLH1 </i>was searched for in the HNPCC colorectal cancers. <h3>RESULTS</h3> All cases were confirmed to be MSI+. The promoter region of <i>hMLH1 </i>was hypermethylated in seven of 10 MSI+ sporadic cancers versus 0 of 10 HNPCC cancers (p&lt;0.002). Evidence of loss of heterozygosity at<i>hMLH1 </i>was observed in eight of the 10 HNPCC colorectal cancers. <h3>CONCLUSION</h3> While mutations and allelic loss are responsible for the MSI+ phenotype in HNPCC cancers, the majority of MSI+ sporadic cancers are hypermethylated in the promoter region of <i>hMLH1.</i> These data further support our argument that tumours from HNPCC patients, which almost always acquire a raised mutation rate, mostly follow a different pathway from MSI+ sporadic tumours.

Germline mutation analysis, microsatellite instability and clinical pathology in Hazakh in China hereditary nonpolyposis colorectal cancer pedigree

Objective To study the significance of mismatch repair (MMR) gene and microsatellite instability (MSI) in Hazakh in China hereditary nonpolyposis colorectal cancer (HNPCC) pedigree.Methods The tumor tissues and normal intestine mucosa of the 105 members of this family were immunohistochemically examined for hMLH1 and hMSH2.The mutation of BAT25,BAT26,D2S123,D5S346 and D17S250 were analyzed with polymerase chain reaction-single-stmded conformation polymorphism (PCR-SSCP) in tissue paraffin imbedding in all cases of the family.Results MSI-positive rate of 17tumor in HNPCC families group was 100 ％,in which there are 16 patients (94.1％) with high frequency microsatellite instability (MSI-H),1 patients with low frequency microsatellite instability (MSI-L)(5.9％).The negative expression of hMLH1 or hMSH2 rate of 17 tumor in HNPCC families group was 100％.There are 44 patients (50.0％) in the other 88 members of the HNPCC family with MSI-H.There are 40 patients with hMLH1 or hMSH2 MMR protein expression absence in the 44 patients with MSI-H.Conclusion HNPCC patients with MSI-H and hMLH1 or hMSH2 MMR protein expression absence have a better consistency with earlier age of onset,right colon cancer incidence and the occurrence of poorly differentiated carcinoma. Key words: Hereditary nonpolyposis colorectal cancer; Microsatellite instability; Mismatch repair gene; Hazakh

Investigating of microsatellites instability in patients with hereditary non-polyposis colorectal cancer in Isfahan

Background:Microsatellites or simple sequence repeats are repeating sequences of deoxyribonucleic acid (DNA). Mutation in mismatch repair (MMR) genes can cause microsatellites instability (MSI) in some tumors. In familial disorder of hereditary non-polyposis colorectal cancer (HNPCC), there is a defect in the mechanism of MMR and clearly defective MMR cause unstable microsatellites. This study has been conducted for investigating the instability of microsatellites in alleles of BAT-26 of MSH2 gene in patients with HNPCC in Isfahan, which is an important prognostic biomarker for the prediction of the treatment outcome.Materials and Methods:DNA extraction from forty HNPCC patients peripheral blood samples were performed by using the DNA extraction kit. The polymerase chain reaction (PCR) reaction to amplify BAT-26 was performed. The PCR products were studied by electrophoresis on agarose gel.Results:The size of specific band was 121 bp out of 40 HNPCC samples and based on the above method, it was shown that 12 cases (30%) demonstrated MSI. Chi-square test showed this difference is statistically significant (P < 0.05).Conclusions:The present study was conducted to evaluate the MSI in HNPCC patients. It was determined that the polymorphisms in BAT-26 of MSH2 gene could detect MSI with high sensitivity. Previous reports as well as our results have shown that the use of BAT-26 alone would be sufficient to identify HNPCC-associated MSH2 gene. Identifying MSI in these genes as a marker for prognosis, according to the present study and other researches is important to predict the treatment outcomes.

Integrative Analysis of Hereditary Nonpolyposis Colorectal Cancer: the Contribution of Allele-Specific Expression and Other Assays to Diagnostic Algorithms

The identification of germline variants predisposing to hereditary nonpolyposis colorectal cancer (HNPCC) is crucial for clinical management of carriers, but several probands remain negative for such variants or bear variants of uncertain significance (VUS). Here we describe the results of integrative molecular analyses in 132 HNPCC patients providing evidences for improved genetic testing of HNPCC with traditional or next generation methods. Patients were screened for: germline allele-specific expression (ASE), nucleotide variants, rearrangements and promoter methylation of mismatch repair (MMR) genes; germline EPCAM rearrangements; tumor microsatellite instability (MSI) and immunohistochemical (IHC) MMR protein expression. Probands negative for pathogenic variants of MMR genes were screened for germline APC and MUTYH sequence variants. Most germline defects identified were sequence variants and rearrangements of MMR genes. Remarkably, altered germline ASE of MMR genes was detected in 8/22 (36.5%) probands analyzed, including 3 cases negative at other screenings. Moreover, ASE provided evidence for the pathogenic role and guided the characterization of a VUS shared by 2 additional probands. No germline MMR gene promoter methylation was observed and only one EPCAM rearrangement was detected. In several cases, tumor IHC and MSI diverged from germline screening results. Notably, APC or biallelic MUTYH germline defects were identified in 2/19 probands negative for pathogenic variants of MMR genes. Our results show that ASE complements gDNA-based analyses in the identification of MMR defects and in the characterization of VUS affecting gene expression, increasing the number of germline alterations detected. An appreciable fraction of probands negative for MMR gene variants harbors APC or MUTYH variants. These results indicate that germline ASE analysis and screening for APC and MUTYH defects should be included in HNPCC diagnostic algorithms.

Survival of patients with Stage III colon cancer is improved in hereditary non-polyposis colorectal cancer compared with sporadic cases. A Danish registry based study

Patients with hereditary non-polyposis colorectal cancer (HNPCC) seem to have a better prognosis than those with sporadic colorectal cancer (CRC). The aim was to compare survival after Stage III CC in patients with HNPCC with those having sporadic CC. A total of 230 patients with hereditary cancer from the Danish HNPCC Register and 3557 patients with sporadic CC from the Danish Colorectal Cancer Database, diagnosed during May 2001-December 2008, were included. HNPCC patients were classified according to mismatch repair mutation status and family pedigree. Sporadic cases had no known family history of cancer. Patient characteristics, geographical differences and survival data were analysed. The overall survival (OS) was better in HNPCC patients compared with sporadic CC after stratification for sex and age (P=0.02; CI 1.04-1.7). The 5-year survival was 70% in HNPCC patients compared with 56% in sporadic CC (P<0.001). No survival difference was found between HNPCC subgroups but a tendency to better OS was seen in patients with Lynch syndrome. No geographical differences in OS were found. The median follow-up was 3.9 (0-9.5) years for HNPCC vs 3.2 (0-9.6) years for sporadic CC. HNPCC patients with Stage III CC have a better OS compared with sporadic CC. No significant difference in OS was found within HNPCC subgroups.