A Novel Mutation of MSH2 Gene in a Patient with Lynch Syndrome Presenting with Thirteen Metachronous Malignancies

Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer (HNPCC), accounts for 2-3% of all colorectal cancers. This autosomal dominant disorder is associated with a predisposition to endometrial, stomach, small bowel, pancreatic, biliary tract, ovary, urinary tract, brain, and skin tumors. Lynch syndrome is caused by the mutation of the MLH1, MSH2 (EPCAM), MSH6, and PMS2 genes. In this article, a case study of a 70-year-old female patient with Lynch syndrome is presented. Over a span of 30 years, the patient underwent multiple surgical procedures for a total of thirteen different malignancies. She was found to have a deleterious pathogenic gene MSH2 (NM_000251.2) variant (mutation) c.1774_1775insT in the 12th exon. This variant, c.1774_1775insT, represents a novel finding, as it has not been previously reported in existing databases or literature. No other case of 13 metachronous tumors in a patient with Lynch syndrome was found in the literature.

Relative Risk of Bladder and Kidney Cancer in Lynch Syndrome: Systematic Review and Meta-Analysis

Background: The association between Lynch syndrome (LS) and a higher risk of upper tract urothelial carcinoma is well established, but its effect on the risk of bladder and kidney cancers remains controversial. This review aimed to compare the relative risk (RR) of bladder and kidney cancer in confirmed LS germline mutation carriers compared to the general population. Methods: Medline, Embase, Cochrane Central, and Google Scholar were searched on 14 July 2022 for studies published in English that reported on the rates of urological cancer in adults with confirmed LS germline mutation. The quality of included studies was assessed using Cochrane’s tool to evaluate risk of bias in cohort studies. Random effects meta-analysis estimated the pooled relative risk of bladder and kidney cancer in LS carriers compared to the general population. The quality of the overall evidence was evaluated using GRADE. Results: Of the 1839 records identified, 5 studies involving 7120 participants from 3 continents were included. Overall, LS carriers had a statistically significantly higher RR of developing bladder cancer (RR: 7.48, 95% CI: 3.70, 15.13) and kidney cancer (RR: 3.97, 95% CI: 1.23, 12.81) compared to unaffected participants (p < 0.01). The quality of the evidence was assessed as “low” due to the inclusion of cohort studies, the substantial heterogeneity, and moderate-to-high risk of bias. Conclusion: Lynch syndrome is associated with a significant increase in the relative risk of kidney and bladder cancer. Clinicians should adopt a lower threshold for germline mutation genetic testing in individuals who present with bladder cancer. Further studies evaluating the role and cost-effectiveness of novel urine-based laboratory tests are needed. High-quality studies in histologically proven renal cell carcinoma and their underlying germline mutations are necessary to strengthen the association with LS.

A practical screening strategy for Lynch syndrome and Lynch syndrome mimics in colorectal cancer

Objectives

The objective of the study is to provide an efficient and practical screening strategy to distinguish a broader spectrum of Lynch syndrome (LS) and LS mimics-associated colorectal cancer (CRC), including Lynch-like syndrome (LLS), constitutional mismatch repair-deficiency, familial CRC type X (FCCTX), and polymerase proofreading-associated polyposis syndrome.

Materials and Methods

1294 cases of CRC samples were detected mismatch repair (MMR) status using immunohistochemistry (IHC) staining, in which the cases with MLH1-deficient CRC underwent BRAF mutation analysis by IHC. Following the personal and/or family history survey, next-generation sequencing (NGS) was used to detect gene variants.

Results

1294 CRC patients were dichotomized into tumors caused by a deficient MMR (dMMR) system and a proficient MMR (pMMR) system after MMR status analysis. 45 patients with suspected sporadic dMMR CRC were then separated from MLH1-deficient CRC though BRAF mutation status analysis by IHC. Following the personal and/or family history survey for 1294 patients, as well as germline genetic testing by NGS, 34 patients were diagnosed as LS (8 cases), SLS (13 cases), LLS ( 6 cases), FCCTX (3 cases), and sporadic CRC (4 cases).

Conclusions

Our screening strategy, which consists of clinical and molecular analyses, is expected to improve the screening efficiency and management for the LS and LS mimics.

Current mismatch repair deficiency tumor testing practices and capabilities: A survey of Australian pathology providers

AIM & METHODS

An electronic survey of the Royal College of Pathologists of Australasia accredited pathology services was conducted to assess Lynch syndrome tumor screening practices and to identify barriers and capabilities to screen newly diagnosed colorectal and endometrial tumors in Australia.

RESULTS

Australia lacks a national policy for universal mismatch repair-deficient (dMMR) testing of incident colorectal and endometrial tumors cases. Routine Lynch syndrome tumor screening program for colorectal and/or endometrial tumors was applied by 95% (37/39) of laboratories. Tumor dMMR screening methods varied; MMR protein immunohistochemistry (IHC) alone was undertaken by 77% of 39 laboratories, 18% performed both IHC and microsatellite instability testing, 5% did not have the capacity to perform in-house testing. For colorectal tumors, 47% (17/36) reported following a universal approach without age limit, 30% (11/36) tested only "red flag" cases; 6% (3/36) on clinician request only. For endometrial tumors, 37% (12/33) reported clinician request generated testing, 27% (9/33) were screening only "red flag" cases, and 12% (4/33) carried out universal screening without an age criteria. BRAF V600E mutation testing of colorectal tumors demonstrating aberrant MLH1 protein expression by IHC was the most common secondary tumor test, with 53% of laboratories performing the test; 15% of laboratories also applied the BRAF V600E test to endometrial tumors with aberrant MLH1 expression despite no evidence for its utility. Tumor testing for MLH1 promoter methylation was performed by less than 15% laboratories.

CONCLUSION

Although use of tumor screening for evidence of dMMR is widely available, protocols for its use in Australia vary widely. This national survey provides a snapshot of the current availability and practice of tumor dMMR screening and identifies the need for a uniform national testing policy.

Lynch syndrome and sextuple primary malignancies

Lynch syndrome or hereditary nonpolyposis colorectal cancer is the most common of hereditary colorectal cancer and accounts for 1-3%. Lynch and Chapelle estimated that it accounts 5-8% for all colorectal cancers. It is an autosomal dominant syndrome characterized by predisposition of various cancers (colorectal, stomach, endometrial, ovarian, renal, small bowel, and hepatobiliary tract) at earlier age than in general population and occurs as a result of mutation in DNA mismatch repair genes. This article presents a rare clinical of a 61-year-old female diagnosed with extracolonic Lynch syndrome with six metachronous tumours acquiring in digestive tract during the period from 1993 to 2014 (over 21 years). No other cases of six primary malignancies in patient with Lynch syndrome have been reported in literature. Upon diagnosis of Lynch syndrome, it is important to screen patient for malignancies of different localization as this syndrome predisposes appearance of various cancers at earlier age than in general population.

Analysis of human MutS homolog 2 missense mutations in patients with colorectal cancer

Germline mutations of DNA mismatch repair gene human MutS homolog 2 (hMSH2) are associated with hereditary nonpolyposis colorectal cancer (HNPCC). A total of one-third of these mutations are missense mutations. Several hMSH2 missense mutations have been identified in patients in East Asia, although their function has not been evaluated. In the present study, the role of ten hMSH2 missense mutations in the pathogenesis of colorectal cancer was examined. The hMSH2/hMSH6 protein interaction system was established using yeast two-hybrid screening. Next, the missense mutations were analyzed for their ability to affect the protein interaction of hMSH2 with its partner hMSH6. Additionally, the Sorting Intolerant from Tolerant tool was applied to predict the effects of different amino acid substitutions. The results demonstrated that certain hMSH2 mutations (L173R and C199R) caused a significant functional change in the human hMutSα complex and were identified to be pathological mutations. The Y408C, D603Y, P696L and S703Y mutations partially affected interaction and partly affected the function of hMSH2. The remaining four variants, T8M, I169V, A370T and Q419K, may be non-functional polymorphisms or could affect protein function through other molecular mechanisms. The present study evaluated the functional consequences of previously unknown missense mutations in hMSH2, and may contribute to improved clinical diagnosis and mutation screening of HNPCC.

Inflammatory potential of the diet and colorectal tumor risk in persons with Lynch syndrome

Background: Persons with Lynch syndrome (LS) have high lifetime risk of developing colorectal tumors (CRTs) because of a germline mutation in one of their mismatch repair (MMR) genes. An important process in the development of CRTs is inflammation, which has been shown to be modulated by diet.Objective: We aimed to investigate the association between the inflammatory potential of the diet and the risk of CRTs in persons with LS.Design: We used the dietary intake of 457 persons with LS from a prospective cohort study to calculate the adapted dietary inflammatory index (ADII). The ADII was split into tertiles in which the highest tertile reflects the most proinflammatory potential of the diet. Cox proportional hazard models, with robust sandwich variance estimates to adjust for dependency within families, were used to calculate HRs and 95% CIs of CRTs by ADII tertile. HRs were adjusted for age, smoking status, and education level, and number of colonoscopies as a time-dependent variable. A potential effect measure modification was explored by stratifying the results by mutated MMR gene, sex, and a history of CRTs. We performed sensitivity analyses by repeating the analyses in non-nonsteroidal anti-inflammatory drug (NSAID) users (n = 315).Results: During a median follow-up time of 59 mo, 200 participants (43.8%) developed CRTs. No significant association was shown between highest compared with lowest ADII tertiles (HR for highest compared with lowest tertiles: 1.37; 95% CI: 0.80, 2.34). Stratification by mutated MMR gene, sex, and CRT history did not show significantly differential associations (P-interactions ≥ 0.64). In non-NSAID users, an HR of 1.60 (95% CI: 0.88, 2.93) for highest compared with lowest tertiles was shown. No significant effect modification was shown in this group either (P-interactions ≥ 0.24).Conclusion: A proinflammatory potential of the diet does not seem to be significantly associated with CRT risk in persons with LS.

Association between the Lynch syndrome gene MSH2 and breast cancer susceptibility in a Canadian familial cancer registry

BACKGROUND

Previous studies assessing breast cancer risk in families with Lynch syndrome (LS) have yielded conflicting results. Furthermore, conclusions are limited by small sample size and few breast cancer outcomes. This study assesses breast cancer risk in a large prospectively followed LS cohort.

METHODS

Pedigrees of 325 unrelated families with LS within the Familial Gastrointestinal Cancer Registry in Canada were examined for breast cancer diagnoses. Standardised incidence ratios (SIR) and lifetime cumulative incidence calculations were used to compare the incidence of breast cancer in mutation carriers with the general population.

RESULTS

Forty-one mutation carriers diagnosed with breast cancer belonging to 34 unrelated families were identified. Mean age at diagnosis was 54 years. The mutation distribution among the LS patients with breast cancer was statistically different from those without breast cancer (p=0.015), reflecting the predominance of MSH2 mutations among affected patients (74%). Eighty-eight per cent of LS families with breast cancer met Amsterdam criteria, compared with 49% of LS families without breast cancer (p=0.03). Lifetime cumulative incidence of breast cancer in female MSH2 mutation carriers in our cohort was 22% (p<0.001). The SIR for breast cancer of female MSH2 mutation carriers in our cohort was 3.11 (95% CI 1.95 to 4.71).

CONCLUSIONS

An increased risk of breast cancer in MSH2 mutation carriers was demonstrated in a Canadian familial cancer registry. Women with breast cancer often had a personal and family history of multiple LS-related malignancies. These results suggest a potential role for intensified breast cancer surveillance among women with LS.

Muir-Torre syndrome caused by exonic deletion of MLH1 due to homologous recombination

BACKGROUND

Muir-Torre syndrome (MTS) is characterized by sebaceous neoplasms with internal malignancies and regarded as a variant of hereditary nonpolyposis colorectal cancer (HNPCC). Pathogenic variations of MTS have been identified in the MSH2, MLH1, and MSH6 genes, with the majority of variations located in MSH2.

OBJECTIVES

To present an MTS patient who was the only individual with skin malignancies within a cancer-prone pedigree and to show the usefulness of RNA-based genetic analysis in the investigation of MTS.

MATERIALS & METHODS

A 77-year-old man who had operated X-ray equipment at his workplace in his twenties was clinically diagnosed with MTS and investigated by RNA-based analysis, multiplex ligation-dependent probe amplification, and genomic DNA sequencing.

RESULTS

The patient had suffered from sebaceous tumours, squamous cell carcinomas of the skin, and colon cancer. The patient's family history was remarkable for visceral malignant diseases. Genetic analysis revealed homologous recombination between two Alu elements within intron 4 and 5 of the MLH1 gene. The rearrangement caused a 1,222-bp deletion, including the entire exon 5. Deletion of exon 5 has previously been reported only in two patients with HNPCC, and not in patients with MTS.

CONCLUSION

For the genetic analysis of MTS, the possibility of rare copy number variations of MLH1, as well as MSH2 variations, should be considered. RNA-based screening using puromycin is recommended in order to identify such variations. It remains unclear why only the proband among the pedigree had skin malignancies, however, the skin carcinogenesis might have been related to occupational radiation exposure.

Diagnostic Approach to Hereditary Colorectal Cancer Syndromes

Approximately 5 to 10% of colorectal cancers develop within a known hereditary syndrome. Specific underlying genetic mutations drive the clinical phenotype and it is imperative to determine the genetic etiology to provide meaningful surveillance and intervention. Recognizing potential patients and families with a hereditary predisposition is the first step in management. Syndromes can be categorized according to polyp burden as polyposis or nonpolyposis. Clinical assessment should start with a personal and family medical history, physical examination, and evaluation for the presence and type of colorectal polyps or cancers. Key information is gained from these simple steps and should guide the specific genetic analysis for diagnosis. Genetic counseling is a critical component to any hereditary colorectal cancer program and should be conducted before genetic testing to provide education about the implications of test results. This review focuses on the thought process that drives initial clinical evaluation and guides genetic testing for patients with suspected hereditary colorectal cancer syndromes.

[The tip of the iceberg: multiple cutaneous sebaceous tumor in colon cancer. Muir-Torre syndrome--case report]

Muir-Torre syndrome is a rare genodermatosis with autosomal dominant inheritance. The syndrome is considered to be a subtype of the hereditary nonpolyposis colorectal cancer (or Lynch-syndrome). In two-third of the cases, it develops as the consequence of germline mutations in mismatch-repair genes--most commonly MutS Homolog-2 and MutL Homolog-1. Its diagnosis can be established if at least one sebaceous tumor (sebaceoma, sebaceous adenoma, epithelioma, carcinoma or basal-cell carcinoma with sebaceous differentiation) and/or keratoacanthoma and at least one internal neoplasm are present. Here the authors present the history of a 52-year-old man with multiple sebaceous carcinomas on his back. Immunohistochemical analysis showed the lack of MutL Homolog-1 protein expression in the tumor cells. Detailed clinical workup in order to identify internal malignancy found malignant coecum tumor. Histopathological evaluation of the sample from the right hemicolectomy revealed mid-grade adenocarcinoma with MutL Homolog-1 and postmeiotic segregation increased-2 deficiency. The detection of the cutaneous sebaceous carcinoma and the application of the modern diagnostic methods resulted in identification of the associated colorectal cancer in an early stage; hence, definitive treatment was available for the patient.

Constitutional mismatch repair deficiency syndrome: Do we know it?

Constitutional mismatch repair deficiency syndrome is a rare autosomal recessive syndrome caused by homozygous mutations in mismatch repair genes. This is characterized by the childhood onset of brain tumors, colorectal cancers, cutaneous manifestations of neurofibromatosis-1 like café au lait spots, hematological malignancies, and occasionally other rare malignancies. Here, we would like to present a family in which the sibling had glioblastoma, and the present case had acute lymphoblastic lymphoma and colorectal cancer. We would like to present this case because of its rarity and would add to literature.

The genetic basis of Lynch syndrome and its implications for clinical practice and risk management

Lynch syndrome is the most common cause of hereditary colon cancer, and accounts for as much as 3% of all colon and endometrial cancers. The identification and management of individuals with Lynch syndrome have evolved over the past 20 years, yet the syndrome remains vastly underdiagnosed. It is important for clinicians to recognize individuals and families who are at risk in order to be able to manage them appropriately and reduce their morbidity and mortality from this condition. This review will touch on the history of Lynch syndrome, the current knowledge of genotype–phenotype correlations, the cancers associated with Lynch syndrome, and management of individuals who are gene carriers.

Familial risk of small intestinal carcinoid and adenocarcinoma

BACKGROUND & AIMS

Small intestinal cancer (SIC) is rare, and its etiology is poorly understood. We compared clusters of families with SICs of different histologic subtypes.

METHODS

By using the nationwide family cancer data sets of Sweden and Finland, we identified a cohort of 9964 first-degree relatives of 1799 patients with SIC, diagnosed from 1961 through 2009. Data were collected from time periods as long as 47 years (mean, 35.4 y), and cancer incidence was determined. Standardized incidence ratios (SIRs) were calculated and stratified by sex, age, time period, and cancer type, using the incidence rates for the entire national population as the reference.

RESULTS

Among the 1799 SIC cases, 1.1% had a sibling with SIC, so the SIR was 11.8 (95% confidence interval [CI], 7.2-18.2); 1.1% had a parent or child with SIC (SIR, 3.5; 95% CI, 2.0-5.6). The SIR of concordant carcinoid histology of SIC among siblings was 28.4 (95% CI, 14.7-49.6; n = 12) and in parent-child pairs was 9.9 (95% CI, 5.4-16.6; n = 14). The familial risk of concordant histologic subtypes increased for siblings diagnosed with adenocarcinoma, but only 2 familial cases were identified. In family members of patients with SIC of the adenocarcinoma subtype, risks of colorectal and bladder cancer were modestly but significantly increased compared with the general population. Family members of patients with SIC of the carcinoid subtype had an increased risk for kidney cancer and polycythemia vera.

CONCLUSIONS

Based on data from our population-based study, first-degree relatives of patients with small intestinal carcinoid tumors have developed these tumors with high incidence. Because of the rareness of this tumor, the absolute risk remains moderate even within families. Gastroenterologists could inform patients with small intestinal carcinoids about the familial risk and encourage counseling for their first-degree relatives. Studies are needed to identify genetic factors that affect susceptibility to SIC.

Endoscopic and surgical management of hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome is a disease characterized by autosomal dominant clustering of colorectal cancer (CRC) as well as other cancers. It is critical for clinicians and surgeons caring for patients with HNPCC to be familiar with their management related to CRC. Based on retrospective studies, screening colonoscopy is recommended every 1 to 2 years beginning at age 20 to 25, or 10 years younger than the earliest CRC in the family (whichever is earlier). HNPCC patients with colon cancer should be considered for total abdominal colectomy rather than a more limited segmental colon resection due to the increased risk of metachronous neoplasia associated with the condition. Rectal cancer in HNPCC has not been well studied, but discussions with the patient regarding surgical management should weigh the risks of metachronous CRC with the morbidity and quality of life issues associated with proctocolectomy. Regardless of the procedure, a patient with HNPCC requires close postoperative endoscopic surveillance of any remaining at-risk mucosa. In terms of chemoprevention, aspirin has been shown to be effective in preventing colorectal neoplasia in prospective trials and should be considered in patients who do not have a contraindication to the drug. Trials for other chemopreventative agents in HNPCC are ongoing. As more is learned about particular genotype-phenotype correlations with Lynch syndrome, this will likely affect surgical decision making. Despite all of these efforts in the management of patients with HNPCC or Lynch syndrome, incident CRCs still occur, thus reinforcing the need for further studies to better understand the optimal management of these patients.

History and pathogenesis of lynch syndrome

Lynch syndrome is the familial clustering of colorectal and endometrial cancers. This syndrome is passed in an autosomal dominant fashion within families with defective mismatch repair as the genetic basis for cancer development in these patients. There remains a group of patients who fit clinical diagnostic criteria for an autosomal dominant familial cancer syndrome, which is phenotypically similar to Lynch syndrome, but for which no mismatch repair mutation is identified. Identification of alternate genetic mutations such as EPCAM and CHEK2 may explain the cancer risk in a small subset of these patients, but continuing work into the genetic basis of colorectal familial cancer syndromes is needed.

DNA repair mechanisms in dividing and non-dividing cells

DNA damage created by endogenous or exogenous genotoxic agents can exist in multiple forms, and if allowed to persist, can promote genome instability and directly lead to various human diseases, particularly cancer, neurological abnormalities, immunodeficiency and premature aging. To avoid such deleterious outcomes, cells have evolved an array of DNA repair pathways, which carry out what is typically a multiple-step process to resolve specific DNA lesions and maintain genome integrity. To fully appreciate the biological contributions of the different DNA repair systems, one must keep in mind the cellular context within which they operate. For example, the human body is composed of non-dividing and dividing cell types, including, in the brain, neurons and glial cells. We describe herein the molecular mechanisms of the different DNA repair pathways, and review their roles in non-dividing and dividing cells, with an eye toward how these pathways may regulate the development of neurological disease.

Colon tumour secretopeptidome: insights into endogenous proteolytic cleavage events in the colon tumour microenvironment

The secretopeptidome comprises endogenous peptides derived from proteins secreted into the tumour microenvironment through classical and non-classical secretion. This study characterised the low-Mr (<3kDa) component of the human colon tumour (LIM1215, LIM1863) secretopeptidome, as a first step towards gaining insights into extracellular proteolytic cleavage events in the tumour microenvironment. Based on two biological replicates, this secretopeptidome isolation strategy utilised differential centrifugal ultrafiltration in combination with analytical RP-HPLC and nanoLC-MS/MS. Secreted peptides were identified using a combination of Mascot and post-processing analyses including MSPro re-scoring, extended feature sets and Percolator, resulting in 474 protein identifications from 1228 peptides (≤1% q-value, ≤5% PEP) - a 36% increase in peptide identifications when compared with conventional Mascot (homology ionscore thresholding). In both colon tumour models, 122 identified peptides were derived from 41 cell surface protein ectodomains, 23 peptides (12 proteins) from regulated intramembrane proteolysis (RIP), and 12 peptides (9 proteins) generated from intracellular domain proteolysis. Further analyses using the protease/substrate database MEROPS, (http://merops.sanger.ac.uk/), revealed 335 (71%) proteins classified as originating from classical/non-classical secretion, or the cell membrane. Of these, peptides were identified from 42 substrates in MEROPS with defined protease cleavage sites, while peptides generated from a further 205 substrates were fragmented by hitherto unknown proteases. A salient finding was the identification of peptides from 88 classical/non-classical secreted substrates in MEROPS, implicated in tumour progression and angiogenesis (FGFBP1, PLXDC2), cell-cell recognition and signalling (DDR1, GPA33), and tumour invasiveness and metastasis (MACC1, SMAGP); the nature of the proteases responsible for these proteolytic events is unknown. To confirm reproducibility of peptide fragment abundance in this study, we report the identification of a specific cleaved peptide fragment in the secretopeptidome from the colon-specific GPA33 antigen in 4/14 human CRC models. This improved secretopeptidome isolation and characterisation strategy has extended our understanding of endogenous peptides generated through proteolysis of classical/non-classical secreted proteins, extracellular proteolytic processing of cell surface membrane proteins, and peptides generated through RIP. The novel peptide cleavage site information in this study provides a useful first step in detailing proteolytic cleavage associated with tumourigenesis and the extracellular environment. This article is part of a Special Issue entitled: An Updated Secretome.

BRAF V600E-specific immunohistochemistry for the exclusion of Lynch syndrome in MSI-H colorectal cancer

The differentiation between hereditary and sporadic microsatellite-unstable (MSI-H) colorectal cancer is a crucial step in Lynch syndrome diagnostics. Within MSI-H colorectal cancers, the BRAF V600E mutation is strongly associated with sporadic origin. Here, we asked whether BRAF V600E-specific immunohistochemistry (clone VE1) is helpful in separating sporadic from Lynch syndrome-associated MSI-H colorectal cancers. To that end, we performed VE1 immunohistochemistry and BRAF sequencing in a series of 91 MSI-H colorectal cancer specimens from patients tested for Lynch syndrome. Concordance of VE1 immunohistochemistry and molecular BRAF mutation status was observed in 90 of 91 (98.9%) MSI-H samples. All 11 tumors classified as BRAF V600E mutation-positive by Sanger sequencing were immunopositive, and 79 (98.8%) of 80 tumors classified as BRAF wild type showed negative staining. All VE1-positive tumors were MLH1- and PMS2-negative by immunohistochemistry. None of the tumors from mismatch repair (MMR) gene germline mutation carriers (n = 28) displayed positive VE1 staining, indicating that BRAF V600E mutation-specific immunostaining has a low risk of excluding Lynch syndrome patients from germline mutation analysis. In conclusion, implementation of VE1 immunohistochemistry was able to detect BRAF-mutated MSI-H colorectal cancers with a sensitivity of 100% and a specificity of 98.8%. Among MLH1-negative colorectal cancers, the rate of VE1-positive lesions was 21%, offering the exclusion of these patients from MMR germline testing. Therefore, we suggest the integration of VE1 immunohistochemistry into the diagnostic panel of Lynch syndrome.

Ureteroscopic management of upper tract urothelial carcinoma (UTUC) in patients with Lynch Syndrome (hereditary nonpolyposis colorectal cancer syndrome)

OBJECTIVES

To report our experience with ureteroscopic laser ablation of upper tract urothelial carcinoma (UTUC) in patients with Lynch Syndrome (LS), as defined by a documented germline mutation in the MSH-2 gene. To increase awareness among urologists about UTUC in this unique patient population and refer to genetic counselling when appropriate.

PATIENTS AND METHODS

Demographic, clinical and pathological data on 13 consecutive patients with UTUC and documented MSH-2 mutation comprising 15 involved renal units were retrospectively collected. Ureteroscopic evaluations involved biopsy and laser treatment with combination holmium/neodymium yttrium aluminum garnet (YAG) lasers. Tumours were graded from 1 to 3 according to the 1973 World Health Organisation classification by a single pathologist evaluating cell block preparations.

RESULTS

The mean patient age at initial presentation was 56.5 years, with six of 13 patients having metachronous bilateral UT disease. The mean follow-up was 59 months with a mean number of surveillances of 12. Of 15 affected renal units, 10/15 (67%) of initial tumours involved the ureter with mean lesion size of 17.5 mm, while five of 15 (33%) involved the intrarenal collecting system with mean lesion size of 25 mm. Ureteroscopy cleared 13/15 (87%) lesions and four of those 13 (31%) needed staged procedures. Renal preservation rate was 14/15 (93%) with one nephroureterectomy and one segmental ureterectomy performed. One patient developed metastatic UTUC after 40 months surveillance. No patient presented with bladder tumours but seven of the 13 (54%) developed them within 10 months of the initial ureteroscopy.

CONCLUSIONS

Patients with LS who develop UTUC present at younger ages and appear to be more likely to have bilateral UT disease over their lifetimes vs sporadic UTUC patients. Ureteroscopic laser ablation offers a good renal preservation rate with reasonable cancer control in patients willing to undergo endoscopic surveillance. Development of new bladder tumours is common.

Preferences for outcomes associated with decisions to undergo or forgo genetic testing for Lynch syndrome

BACKGROUND

Current guidelines recommend offering genetic testing for Lynch syndrome to individuals whose tumors suggest this condition and to relatives of affected individuals. Little is known, however, regarding how patients view the prospect of such testing. In addition, data on preferences (utilities) for the potential outcomes of testing decisions for use in cost-effectiveness analyses are lacking.

METHODS

Time tradeoff utilities were elicited for 10 potential outcomes of Lynch syndrome testing decisions and 3 associated cancers from 70 participants, representing a range of knowledge about and experiences with Lynch syndrome.

RESULTS

Highest mean utilities were assigned to scenarios in which only the assessor's sibling had Lynch-associated colorectal cancer (ranging from 0.669 ± 0.231 to 0.760 ± 0.220). Utilities assigned to scenarios in which the assessor had Lynch-associated colorectal cancer ranged from 0.605 ± 0.252 to 0.682 ± 0.246, whereas the lowest mean utilities were assigned to 2 of the general cancer states (0.601 ± 0.238 and 0.593 ± 0.272 for colorectal and ovarian cancer respectively). Only 43% of the sample assigned higher values to undergoing Lynch testing and receiving negative results versus forgoing Lynch testing, whereas 50% assigned higher values to undergoing rather than forgoing surgery to prevent a subsequent cancer.

CONCLUSIONS

Genetic testing for Lynch syndrome, regardless of results, can have profound effects on quality of life; the utilities we collected can be used to incorporate these effects into cost-effectiveness analyses. Importantly, preferences for the potential outcomes of testing vary substantially, calling into question the extent to which patients would avail themselves of such testing if it were offered to them.

Inherited colorectal cancer syndromes

Colorectal cancer is common in the Western world; ~5% of individuals diagnosed with colorectal cancer have an identifiable inherited genetic predisposition to this malignancy. Genetic testing and rational clinical management recommendations currently exist for the management of individuals with a variety of colorectal cancer syndromes, including hereditary nonpolyposis colorectal cancer (HNPCC, also known as Lynch syndrome), familial adenomatous polyposis (FAP), MYH-associated polyposis (MAP), and the hamartomatous polyposis syndromes (Peutz-Jeghers, juvenile polyposis, and Cowden disease). In addition to colorectal neoplasia, these syndromes frequently predispose carriers to a variety of extracolonic cancers. The elucidation of the genetic basis of several colorectal cancer predisposition syndromes over the past two decades has allowed for better management of individuals who are either affected with, or at-risk for inherited colorectal cancer syndromes. Appropriate multidisciplinary management of these individuals includes genetic counseling, genetic testing, clinical screening, and treatment recommendations.

A review of statistical methods for testing genetic anticipation: looking for an answer in Lynch syndrome

Anticipation, manifested through decreasing age of onset or increased severity in successive generations, has been noted in several genetic diseases. Statistical methods for genetic anticipation range from a simple use of the paired t-test for age of onset restricted to affected parent-child pairs to a recently proposed random effects model which includes extended pedigree data and unaffected family members [Larsen et al., 2009]. A naive use of the paired t-test is biased for the simple reason that age of onset has to be less than the age at ascertainment (interview) for both affected parent and child, and this right truncation effect is more pronounced in children than in parents. In this study, we first review different statistical methods for testing genetic anticipation in affected parent-child pairs that address the issue of bias due to right truncation. Using affected parent-child pair data, we compare the paired t-test with the parametric conditional maximum likelihood approach of Huang and Vieland [1997] and the nonparametric approach of Rabinowitz and Yang [1999] in terms of Type I error and power under various simulation settings and departures from the modeling assumptions. We especially investigate the issue of multiplex ascertainment and its effect on the different methods. We then focus on exploring genetic anticipation in Lynch syndrome and analyze new data on the age of onset in affected parent-child pairs from families seen at the University of Michigan Cancer Genetics clinic with a mutation in one of the three main mismatch repair (MMR) genes. In contrast to the clinic-based population, we re-analyze data on a population-based Lynch syndrome cohort, derived from the Danish HNPCC-register. Both datasets indicate evidence of genetic anticipation in Lynch syndrome. We then expand our review to incorporate recently proposed statistical methods that consider family instead of affected pairs as the sampling unit. These prospective censored regression models offer additional flexibility to incorporate unaffected family members, familial correlation and other covariates into the analysis. An expanded dataset from the Danish HNPCC-register is analyzed by this alternative set of methods.

Microsatellite instability in colorectal cancer

Microsatellite instability (MSI) is a hypermutable phenotype caused by the loss of DNA mismatch repair activity. MSI is detected in about 15% of all colorectal cancers; 3% are of these are associated with Lynch syndrome and the other 12% are caused by sporadic, acquired hypermethylation of the promoter of the MLH1 gene, which occurs in tumors with the CpG island methylator phenotype. Colorectal tumors with MSI have distinctive features, including a tendency to arise in the proximal colon, lymphocytic infiltrate, and a poorly differentiated, mucinous or signet ring appearance. They have a slightly better prognosis than colorectal tumors without MSI and do not have the same response to chemotherapeutics. Discovery of MSI in colorectal tumors has increased awareness of the diversity of colorectal cancers and implications for specialized management of patients.

Review of the Lynch syndrome: history, molecular genetics, screening, differential diagnosis, and medicolegal ramifications

More than one million patients will manifest colorectal cancer (CRC) this year of which, conservatively, approximately 3% (approximately 30,700 cases) will have Lynch syndrome (LS), the most common hereditary CRC predisposing syndrome. Each case belongs to a family with clinical needs that require genetic counseling, DNA testing for mismatch repair genes (most frequently MLH1 or MSH2) and screening for CRC. Colonoscopy is mandated, given CRC's proximal occurrence (70-80% proximal to the splenic flexure). Due to its early age of onset (average 45 years of age), colonoscopy needs to start by age 25, and because of its accelerated carcinogenesis, it should be repeated every 1 to 2 years through age 40 and then annually thereafter. Should CRC occur, subtotal colectomy may be necessary, given the marked frequency of synchronous and metachronous CRC. Because 40-60% of female patients will manifest endometrial cancer, tailored management is essential. Additional extracolonic cancers include ovary, stomach, small bowel, pancreas, hepatobiliary tract, upper uroepithelial tract, brain (Turcot variant) and sebaceous adenomas/carcinomas (Muir-Torre variant). LS explains only 10-25% of familial CRC.

Mismatch repair genes in Lynch syndrome: a review

Lynch syndrome represents 1-7% of all cases of colorectal cancer and is an autosomal-dominant inherited cancer predisposition syndrome caused by germline mutations in deoxyribonucleic acid (DNA) mismatch repair genes. Since the discovery of the major human genes with DNA mismatch repair function, mutations in five of them have been correlated with susceptibility to Lynch syndrome: mutS homolog 2 (MSH2); mutL homolog 1 (MLH1); mutS homolog 6 (MSH6); postmeiotic segregation increased 2 (PMS2); and postmeiotic segregation increased 1 (PMS1). It has been proposed that one additional mismatch repair gene, mutL homolog 3 (MLH3), also plays a role in Lynch syndrome predisposition, but the clinical significance of mutations in this gene is less clear. According to the InSiGHT database (International Society for Gastrointestinal Hereditary Tumors), approximately 500 different LS-associated mismatch repair gene mutations are known, primarily involving MLH1 (50%) and MSH2 (40%), while others account for 10%. Much progress has been made in understanding the molecular basis of Lynch Syndrome. Molecular characterization will be the most accurate way of defining Lynch syndrome and will provide predictive information of greater accuracy regarding the risks of colon and extracolonic cancer and enable optimal cancer surveillance regimens.

Is surveillance of the small bowel indicated for Lynch syndrome families?

BACKGROUND

Small bowel cancer (SBC) is one of the tumours associated with Lynch syndrome (LS). To advise on screening for this tumour it is paramount to be informed about the lifetime risk. The aim of this study was to calculate the lifetime risk of SBC in LS and to identify possible risk factors.

METHODS

Clinical and pathological data were collected on 1496 proven or putative carriers of a mismatch repair gene mutation from 189 families. Kaplan-Meier survival analysis was used to calculate the lifetime risk and to assess potential risk factors.

RESULTS

28 (1.9%) of the 1496 (putative) mutation carriers were identified with SBC. The median age at diagnosis was 52 years (range 23-69 years). The lifetime risk of developing SBC was 4.2%. There was no difference in risk between males and females (log rank: p = 0.2470), or between MLH1 and MSH2 mutation carriers (log rank: p = 0.2754). SBC was not observed in MSH6 mutation carriers (n = 203). The previous occurrence of colorectal cancer and a family history of SBC did not increase the risk significantly.

CONCLUSIONS

Approximately, one out of 25 mutation carriers will develop SBC during life. No specific risk factors were identified. The risk appeared to be too low to advise screening by means of an invasive burdensome procedure like double balloon enteroscopy. However, screening by a non-invasive procedure (videocapsule endoscopy) might be considered if future studies will show its cost effectiveness. In patients with unexplained abdominal complaints and/or unexplained iron deficiency anaemia SBC should be considered.

Microsatellite instability and frameshift mutations in the Bax gene in hereditary nonpolyposis colorectal carcinoma

We studied microsatellite instability (MI) and bax gene abnormalities in colorectal carcinomas from 36 patients diagnosed as having hereditary nonpolyposis colorectal cancers (HNPCC) according to the clinical criteria (12 with confirmed HNPCC in group A and 24 at high risk of HNPCC in group B) and from 20 randomly selected patients with other colorectal cancers. MI was examined at 4 dinucleotide microsatellite loci and one mononucleotide locus. Frameshift mutations in the bax gene were detected by polymerase chain reaction-single strand conformation polymorphism analysis. MI was detected in 7 of the 12 patients in group A and 12 of the 24 in group B. Three MI patterns were identified: type 1, MI in both mono- and dinucleotide repeats; type 2, MI only in mononucleotide repeats and type 3, MI only in dinucleotide repeats. Most MI-positive patients in group A showed type 1 MI, whereas in group B, 5 showed type 1, 3 showed type 2 and 4 showed type 3. Frameshift mutations in the bax gene correlated strongly with type 1 and type 2 MI. These results indicate that mutations of different DNA mismatch repair genes may cause several types of MI and result in several different clinical phenotypes of HNPCC. The bax gene may be one of the target genes which play a role in the tumorigenesis of HNPCC.

Loss or somatic mutations of hMSH2 occur in hereditary nonpolyposis colorectal cancers with hMSH2 germline mutations

Hereditary nonpolyposis colorectal cancer (HNPCC) is a major cancer susceptibility syndrome known to be caused by the inheritance of mutations in DNA mismatch repair genes, such as hMSH2, hMLH1, hPMS1 and hPMS2. To investigate the role of genetic alterations of hMSH2 in HNPCC tumorigenesis, we analyzed 36 Japanese HNPCC kindreds as to hMSH2 germline mutations. Moreover, we also examined somatic mutations of hMSH2 or loss of heterozygosity at or near the hMSH2 locus in the tumors from the hMSH2-related kindreds. Germline mutations were detected in five HNPCC kindreds (5/36, 14%). Among them, three were nonsense mutations, one was a frameshift mutation and the other was a mutation in an intron where the mutation affected splicing. Loss of heterozygosity in four and somatic mutations in one were detected among the eight tumors with hMSH2 germline mutations. All these alterations were only detected in genomic instability(+) tumors, i.e., not in genomic instability(-) ones, indicating that mutations of hMSH2 were responsible for at least some of the tumors with genomic instability. These data establish a basis for the presymptomatic diagnosis of HNPCC patients, and constitute further evidence that both DNA mismatch repair genes and tumor suppressor genes may share the same requirement, i.e., two hits are necessary to inactivate the gene function.