Identification of MYH mutation carriers in colorectal cancer: a multicenter, case-control, population-based study

Phenotype correlations with pathogenic DNA variants in the MUTYH gene

MUTYH -associated polyposis (MAP) is an autosomal recessive disorder where the inheritance of constitutional biallelic pathogenic MUTYH variants predisposes a person to the development of adenomas and colorectal cancer (CRC). It is also associated with extracolonic and extraintestinal manifestations that may overlap with the phenotype of familial adenomatous polyposis (FAP). Currently, there are discrepancies in the literature regarding whether certain phenotypes are truly associated with MAP. This narrative review aims to explore the phenotypic spectrum of MAP to better characterise the MAP phenotype. A literature search was conducted to identify articles reporting on MAP-specific phenotypes. Clinical data from 2109 MAP patients identified from the literature showed that 1123 patients (53.2%) had CRC. Some patients with CRC had no associated adenomas, suggesting that adenomas are not an obligatory component of MAP. Carriers of the two missense founder variants, and possibly truncating variants, had an increased cancer risk when compared to those who carry other pathogenic variants. It has been suggested that somatic G:C>T:A transversions are a mutational signature of MAP, and could be used as a biomarker in screening and identifying patients with atypical MAP, or in associating certain phenotypes with MAP. The extracolonic and extraintestinal manifestations that have been associated with MAP include duodenal adenomas, duodenal cancer, fundic gland polyps, gastric cancer, ovarian cancer, bladder cancer and skin cancer. The association of breast cancer and endometrial cancer with MAP remains disputed. Desmoids and Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPEs) are rarely reported in MAP, but have long been seen in FAP patients, and thus could act as a distinguishing feature between the two. This collection of MAP phenotypes will assist in the assessment of pathogenic MUTYH variants using the American College of Medical Genetics and the Association for Molecular Pathology (ACMG/AMP) Variant Interpretation Guidelines, and ultimately improve patient care.

The Progress of Colorectal Polyposis Syndrome in Chinese Population

The pathogenesis, clinical phenotype, treatment strategy, and family management of hereditary tumor syndromes are different from those of sporadic tumors. Nearly a quarter of patients with colorectal cancer show significant familial aggregation and genetic predisposition, and 5 to 10% are associated with definite genetic factors. According to the clinical phenotype, it can be divided into nonpolyposis syndrome and polyposis syndrome. Among the polyposis syndrome patients with definite clinical symptoms, there are still some patients with unknown etiology (especially attenuated familial adenomatous polyposis), which is a difficult problem in clinical diagnosis and treatment. Therefore, for this rare disease, it is urgent to carry out multicenter studies, complete the gene variation spectrum, explore new pathogenic factors, and accumulate clinical experience. This article mainly introduces the research progress and related work of colorectal polyposis syndrome in China.

Clinical Multigene Panel Testing Identifies Racial and Ethnic Differences in Germline Pathogenic Variants Among Patients With Early-Onset Colorectal Cancer

PURPOSE

The early-onset colorectal cancer (EOCRC) burden differs across racial/ethnic groups, yet the role of germline genetic predisposition in EOCRC disparities remains uncharacterized. We defined the prevalence and spectrum of inherited colorectal cancer (CRC) susceptibility gene variations among patients with EOCRC by race and ethnicity.

PATIENTS AND METHODS

We included individuals diagnosed with a first primary CRC between age 15 and 49 years who identified as Ashkenazi Jewish, Asian, Black, Hispanic, or White and underwent germline genetic testing of 14 CRC susceptibility genes performed by a clinical testing laboratory. Variant comparisons by racial and ethnic groups were evaluated using chi-square tests and multivariable logistic regression adjusted for sex, age, CRC site, and number of primary colorectal tumors.

RESULTS

Among 3,980 patients with EOCRC, a total of 530 germline pathogenic or likely pathogenic variants were identified in 485 individuals (12.2%). By race/ethnicity, 12.7% of Ashkenazim patients, 9.5% of Asian patients, 10.3% of Black patients, 14.0% of Hispanic patients, and 12.4% of White patients carried a germline variant. The prevalence of Lynch syndrome (P = .037), as well as APC, CHEK2, MLH1, monoallelic MUTYH, and PTEN variants, varied by race/ethnicity among patients with EOCRC (all P < .026). Ashkenazim and Hispanic patients had significantly higher odds of presenting with a pathogenic APC variant, which included p.I1307K (odds ratio [OR], 2.67; 95% CI, 1.30 to 5.49; P = .007) and MLH1 variant (OR, 8.69; 95% CI, 2.68 to 28.20; P = .0003), respectively, versus White patients in adjusted models.

CONCLUSION

Germline genetic features differed by race/ethnicity in young patients with CRC, suggesting that current multigene panel tests may not be representative of EOCRC risk in diverse populations. Further study is needed to optimize genes selected for genetic testing in EOCRC via ancestry-specific gene and variant discovery to yield equitable clinical benefits for all patients and to mitigate inequities in disease burden.

Hereditary Cancer Syndromes: A Comprehensive Review with a Visual Tool

Hereditary cancer syndromes account for nearly 10% of cancers even though they are often underdiagnosed. Finding a pathogenic gene variant could have dramatic implications in terms of pharmacologic treatments, tailored preventive programs, and familiar cascade testing. However, diagnosing a hereditary cancer syndrome could be challenging because of a lack of validated testing criteria or because of their suboptimal performance. In addition, many clinicians are not sufficiently well trained to identify and select patients that could benefit from a genetic test. Herein, we searched the available literature to comprehensively review and categorize hereditary cancer syndromes affecting adults with the aim of helping clinicians in their daily clinical practice through a visual tool.

Monoallelic MUTYH pathogenic variants ascertained via multi-gene hereditary cancer panels are not associated with colorectal, endometrial, or breast cancer

We aimed to determine whether monoallelic MUTYH pathogenic and likely pathogenic variants (PVs) are associated with colorectal, breast, and endometrial cancer. Cases were individuals with colorectal, female breast, or endometrial cancer who reported European ancestry alone and underwent a multi-gene hereditary cancer panel at a large reference laboratory. Controls were individuals of European (non-Finnish) descent from GnomAD with cancer cohorts removed. We performed a Fisher's exact test to generate odds ratios (ORs) with 95% confidence intervals (CI). Prevalence of single MUTYH PVs in cancer cohorts versus controls, respectively, was: colorectal cancer, 2.1% vs. 1.8% (OR 1.2, 95% CI 0.99-1.5, p = 0.064); breast cancer 1.9% vs. 1.7% (OR 1.1, 95% CI 0.96-1.3, p = 0.15); and endometrial cancer, 1.7% vs. 1.7% (OR 0.98; 95% CI 0.70-1.3, p = 0.94). Using the largest colorectal and endometrial cancer cohorts and one of the largest breast cancer cohorts from a single case-control study, we did not observe a significant difference in the prevalence of monoallelic MUTYH PVs in these cohorts compared to controls. Additionally, frequencies among cancer cohorts were consistent with the published MUTYH carrier frequency of 1-2%. These findings suggest there is no association between colorectal, endometrial, or breast cancer and MUTYH heterozygosity in individuals of European ancestry.

Incident Cancer Risk and Signatures Among Older MUTYH Carriers: Analysis of Population-Based and Genomic Cohorts

MUTYH carriers have an increased colorectal cancer risk in case-control studies, with loss of heterozygosity (LOH) as the presumed mechanism. We evaluated cancer risk among carriers in a prospective, population-based cohort of older adults. In addition, we assessed if cancers from carriers demonstrated mutational signatures (G:C>T:A transversions) associated with early LOH. We calculated incident risk of cancer and colorectal cancer among 13,131 sequenced study participants of the ASPirin in Reducing Events in the Elderly cohort, stratified by sex and adjusting for age, smoking, alcohol use, BMI, polyp history, history of cancer, and aspirin use. MUTYH carriers were identified among 13,033 participants in The Cancer Genome Atlas and International Cancer Genome Consortium, and somatic signatures of cancers were analyzed. Male MUTYH carriers demonstrated an increased risk for overall cancer incidence [multivariable HR, 1.66; 95% confidence interval (CI), 1.03-2.68; P = 0.038] driven by increased colorectal cancer incidence (multivariable HR, 3.55; 95% CI, 1.42-8.78; P = 0.007), as opposed to extracolonic cancer incidence (multivariable HR, 1.40; 95% CI, 0.81-2.44; P = 0.229). Female carriers did not demonstrate increased risk of cancer, colorectal cancer, or extracolonic cancers. Analysis of mutation signatures from cancers of MUTYH carriers revealed no significant contribution toward early mutagenesis from widespread G:C>T:A transversions among gastrointestinal epithelial cancers. Among cancers from carriers, somatic transversions associated with base-excision repair deficiency are uncommon, suggestive of diverse mechanisms of carcinogenesis in carriers compared with those who inherit biallelic MUTYH mutations.

PREVENTION RELEVANCE

Despite absence of loss of heterozygosity in colorectal cancers, elderly male MUTYH carriers appeared to be at increased of colorectal cancer.

Identifying colorectal cancer caused by biallelic MUTYH pathogenic variants using tumor mutational signatures

Carriers of germline biallelic pathogenic variants in the MUTYH gene have a high risk of colorectal cancer. We test 5649 colorectal cancers to evaluate the discriminatory potential of a tumor mutational signature specific to MUTYH for identifying biallelic carriers and classifying variants of uncertain clinical significance (VUS). Using a tumor and matched germline targeted multi-gene panel approach, our classifier identifies all biallelic MUTYH carriers and all known non-carriers in an independent test set of 3019 colorectal cancers (accuracy = 100% (95% confidence interval 99.87-100%)). All monoallelic MUTYH carriers are classified with the non-MUTYH carriers. The classifier provides evidence for a pathogenic classification for two VUS and a benign classification for five VUS. Somatic hotspot mutations KRAS p.G12C and PIK3CA p.Q546K are associated with colorectal cancers from biallelic MUTYH carriers compared with non-carriers (p = 2 × 10-23 and p = 6 × 10-11, respectively). Here, we demonstrate the potential application of mutational signatures to tumor sequencing workflows to improve the identification of biallelic MUTYH carriers.

Utility of germline multi-gene panel testing in patients with endometrial cancer

OBJECTIVES

Patients with germline mutations in mismatch repair genes (MLH1, MSH2, MSH6, PMS2) associated with Lynch syndrome (LS) have an increased lifetime risk of endometrial cancer (EC). Multi-gene panel testing (MGPT) is a recent hereditary cancer risk tool enabling next-generation sequencing of numerous genes in parallel. We determined the prevalence of actionable cancer predisposition gene mutations identified through MGPT in an EC patient cohort.

METHODS

A single center retrospective cohort study was conducted of patients with EC who had a clinical indication for genetic testing and who underwent MGPT as part of standard of care treatment between 2012 and 2021. Pathogenic mutations were identified and actionable mutations were defined as those with clinical management implications. Additionally, the number of individuals identified with LS was compared between MGPT and tumor-based screening.

RESULTS

The study included a total of 224 patients. Thirty-three patients [14.7%, 95% confidence interval (CI) = 10.4-20.1] had actionable mutations. Twenty-one patients (9.4%, 95% CI = 5.9-14.0) had mutations in LS genes (4 MLH1, 5 MSH2, 7 MSH6, 4 PMS2, 1 Epcam-MSH2). MGPT revealed two patients with LS (9.5% of LS cases) not identified through routine tumor-based screening. Thirteen patients (5.8%, 95% CI = 3.1-9.7) had at least one actionable mutation in a non-Lynch syndrome gene (6 CHEK2, 2 BRCA2, 2 ATM, 2 APC, 1 RAD51C, 1 BRCA1).

CONCLUSIONS

Germline MGPT is both feasible and informative as it identifies LS cases not found on tumor testing as well as additional actionable mutations in patients with EC.

Comparative genomic signatures in young and old Chinese patients with colorectal cancer

BACKGROUND

Occurrence at a young age is known to be associated with unique clinical features in colorectal cancer (CRC). However, the genomic differences between young and old patients with CRC are not well elucidated and, to the best of our knowledge, have never been investigated in a Chinese population.

METHODS

Tumor tissue samples from 29 young (age ≤50 years) and 46 old (age >50 years) patients with CRC were collected. Targeted sequencing of 808 cancer-related genes was conducted to characterize the genomic landscape for Chinese CRC.

RESULTS

Overall, mutational profiles exhibited notable differences between the two groups. In particular, APC and PIK3CA mutations were more frequently observed in old patients (p = 0.009 and p = 0.012, respectively), while SMAD4 mutations tended to occur in young patients (p = 0.054). Mutation loci distributions of KRAS in the young cohort differed from those in the old cohort, and a higher frequency of KRAS codon 12 mutations was potentially associated with a young age (p = 0.076). The frequencies of clinically actionable alterations were analyzed by defined age categories, which unveiled a distinctive targeted genomic profile in the young group. Furthermore, among patients with mismatch repair-proficient (pMMR) CRC, tumor mutation burden (TMB) was positively correlated with age (Pearson's r = 0.306, p = 0.011), and genomic alterations associated with high TMB in young patients differentiated from those in old patients.

CONCLUSIONS

These findings revealed different molecular characterization between young and old Chinese patients with CRC, which may provide novel insights for the personalized treatment of CRC.

Risk of colorectal adenomas and cancer in monoallelic carriers of MUTYH pathogenic variants: a single-centre experience

PURPOSE

The carrier frequency of MUTYH pathogenic variants in the population may be as high as one in 45. Some studies have found an increased risk of colorectal cancer (CRC) in monoallelic carriers of MUTYH pathogenic variants, but the role of early surveillance colonoscopy is not conclusive. This study aimed to assess the outcomes of colonoscopy surveillance in MUTYH carriers.

METHODS

Patients, with a monoallelic pathogenic variant in MUTYH, found at cascade testing, were identified from the St Mark's Hospital Polyposis Registry database. Findings at surveillance colonoscopy were reviewed.

RESULTS

Two hundred and forty-nine carriers were identified, of whom 125 had undergone at least one surveillance colonoscopy. Twenty-eight patients (22%) developed at least one adenoma; all adenomas had low-grade dysplasia (LGD). The median age at first colonoscopy was 36 years (range 16-75 years). The median age at first adenoma detection was 43 years (range 22-75 years). The cumulative incidence of adenoma development by age 30, 40, 50, 60 and 70 years was 3.2%, 8.8%, 15.2%, 18.4% and 20.8%, respectively. No CRCs were observed.

CONCLUSIONS

Our cohort of monoallelic carriers of MUTYH pathogenic variants is a relatively younger group than adults entering population screening colonoscopy, but a high adenoma rate was not observed. No CRCs were detected, suggesting that current guidance that these individuals should be managed in the same way as the general population is reasonable.

MUTYH: Not just polyposis

MUTYH is a base excision repair enzyme, it plays a crucial role in the correction of DNA errors from guanine oxidation and may be considered a cell protective factor. In humans it is an adenine DNA glycosylase that removes adenine misincorporated in 7,8-dihydro-8-oxoguanine (8-oxoG) pairs, inducing G:C to T:A transversions. MUTYH functionally cooperates with OGG1 that eliminates 8-oxodG derived from excessive reactive oxygen species production. MUTYH mutations have been linked to MUTYH associated polyposis syndrome (MAP), an autosomal recessive disorder characterized by multiple colorectal adenomas. MAP patients show a greatly increased lifetime risk for gastrointestinal cancers. The cancer risk in mono-allelic carriers associated with one MUTYH mutant allele is controversial and it remains to be clarified whether the altered functions of this protein may have a pathophysiological involvement in other diseases besides familial gastrointestinal diseases. This review evaluates the role of MUTYH, focusing on current studies of human neoplastic and non-neoplastic diseases different to colon polyposis and colorectal cancer. This will provide novel insights into the understanding of the molecular basis underlying MUTYH-related pathogenesis. Furthermore, we describe the association between MUTYH single nucleotide polymorphisms (SNPs) and different cancer and non-cancer diseases. We address the utility to increase our knowledge regarding MUTYH in the light of recent advances in the literature with the aim of a better understanding of the potential for identifying new therapeutic targets. Considering the multiple functions and interactions of MUTYH protein, its involvement in pathologies based on oxidative stress damage could be hypothesized. Although the development of extraintestinal cancer in MUTYH heterozygotes is not completely defined, the risk for malignancies of the duodenum, ovary, and bladder is also increased as well as the onset of benign and malignant endocrine tumors. The presence of MUTYH pathogenic variants is an independent predictor of poor prognosis in sporadic gastric cancer and in salivary gland secretory carcinoma, while its inhibition has been shown to reduce the survival of pancreatic ductal adenocarcinoma cells. Furthermore, some MUTYH SNPs have been associated with lung, hepatocellular and cervical cancer risk. An additional role of MUTYH seems to contribute to the prevention of numerous other disorders with an inflammatory/degenerative basis, including neurological and ocular diseases. Finally, it is interesting to note that MUTYH could be a new therapeutic target and future studies will shed light on its specific functions in the prevention of diseases and in the improvement of the chemo-sensitivity of cancer cells.

Multi-gene panel testing confirms phenotypic variability in MUTYH-Associated Polyposis

Biallelic pathogenic variants (PVs) in MUTYH cause MUTYH-Associated Polyposis (MAP), which displays phenotypic overlap with other hereditary colorectal cancer (CRC) syndromes including Familial Adenomatous Polyposis (FAP) and Lynch syndrome. We report the phenotypic spectrum of MAP in the context of multi-gene hereditary cancer panel testing. Genetic testing results and clinical histories were reviewed for individuals with biallelic MUTYH PVs detected by panel testing at a single commercial molecular diagnostic laboratory. Biallelic MUTYH PVs were identified in 82 individuals (representing 0.2% of tested individuals) with most (75/82; 91.5%) reporting a personal history of CRC and/or polyps. Ten percent (6/61) of individuals reporting polyp number reported fewer than 10 polyps and therefore did not meet current MAP testing criteria. Extracolonic cancers (21/82; 25.6%), multiple primaries (19/82; 23.2%), Lynch-like (17/82; 20.7%) and FAP-like phenotypes (16/82; 19.5%) were observed, including individuals with mismatch repair-deficient tumors (3/82; 3.7%), sebaceous neoplasms (2/82; 2.4%), or congenital hypertrophy of the retinal pigment epithelium (CHRPE) (2/82; 2.4%). We report what is to our knowledge the first cohort of individuals with MAP identified by panel testing. The phenotypic spectrum of MAP observed in this cohort aligns with the published literature. In addition to standard indications for MUTYH testing, our data provide evidence to support consideration of MAP in the differential diagnosis for some individuals with fewer than 10 polyps, depending on other personal and/or family history, as well as for individuals suspected to have Lynch syndrome or FAP.

Lynch-like syndrome is as frequent as Lynch syndrome in early-onset nonfamilial nonpolyposis colorectal cancer

Early-onset (<50 years-old) nonpolyposis nonfamilial colorectal cancer (EO NP NF CRC) is a common clinical challenge. Although Lynch syndrome (LS) is associated with EO CRC, the frequency of this syndrome in the EO NF cases remains unknown. Besides, mismatch repair deficient (MMRd) CRCs with negative MMR gene testing have recently been described in up to 60% of cases and termed "Lynch-like syndrome" (LLS). Management and counseling decisions of these patients are complicated because of unconfirmed suspicions of hereditary cancer. To define the prevalence of MMR deficient CRCs, LS and LLS in patients with EO NP NF CRC, we recruited 102 patients with a first diagnosis of NP NF CRC ≤ 50 years old during 2003-2009 who underwent genetic counseling at our institution in Argentina. Tumor immunohistochemical (IHC) MMR for protein expression and microsatellite instability (MSI) status were evaluated, and in those with loss of MLH1 expression by IHC, somatic BRAF V600E mutation and both somatic and germline MLH1 methylation levels were studied. Tumors characterized as MMRd without somatic BRAF mutation nor MLH1 methylation were sent for germline analysis. Twenty one (20.6%) tumors were MMRd. Fourteen of 16 putative LS cases underwent germline testing: 6 pathogenic mutations were identified and 8 cases had no identifiable pathogenic mutations. The prevalence of LS and LLS in this cohort was 5.8% (6/102) and 7.8% (8/102), respectively. As a conclusion we found that 20% of patients with EO NP NF CRC have MMRd tumors, and at least half of these are likely to have LLS.

Genetic predisposition to colorectal cancer: syndromes, genes, classification of genetic variants and implications for precision medicine

This article reviews genes and syndromes associated with predisposition to colorectal cancer (CRC), with an overview of gene variant classification. We include updates on the application of preventive and therapeutic measures, focusing on the use of non-steroidal anti-inflammatory drugs (NSAIDs) and immunotherapy. Germline pathogenic variants in genes conferring high or moderate risk to cancer are detected in 6-10% of all CRCs and 20% of those diagnosed before age 50. CRC syndromes can be subdivided into nonpolyposis and polyposis entities, the most common of which are Lynch syndrome and familial adenomatous polyposis, respectively. In addition to known and novel genes associated with highly penetrant CRC risk, identification of pathogenic germline variants in genes associated with moderate-penetrance cancer risk and/or hereditary cancer syndromes not traditionally linked to CRC may have an impact on genetic testing, counseling, and surveillance. The use of multigene panels in genetic testing has exposed challenges in the classification of variants of uncertain significance. We provide an overview of the main classification systems and strategies for improving these. Finally, we highlight approaches for integrating chemoprevention in the care of individuals with genetic predisposition to CRC and use of targeted agents and immunotherapy for treatment of mismatch repair-deficient and hypermutant tumors. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

MutYH-associated polyposis

MutYH-associated polyposis is the only polyposis syndrome with an autosomal recessive type of inheritance, often phenotypically similar to a weakened form of familial adenomatous polyposis. For the development of the disease mutations in both alleles of the gene are required, but an increased risk of developing colorectal cancer in carriers of monoallelic mutations is noted. The diagnosis of MutYH-associated polyposis should be suspected in a patient with colorectal cancer over 45 years old on the background of polyps in the colon. The review presents modern algorithms for diagnostic and treatment of the disease.

Hereditary Colorectal Cancer Syndromes

OBJECTIVES

To review the most common hereditary colorectal cancer syndromes with known associated mutated genes, associated cancer risks, and current screening and prevention current.

DATA SOURCES

Online search of PubMed, EBSCOhost, and Medline, review of the literature for each syndrome described.

CONCLUSION

Hereditary colon cancer accounts for approximately 10% of all colorectal cancers in the United States. There are multiple hereditary colorectal cancer syndromes known with respective associated genetic mutations, cancer risks, and screening and prevention recommendations.

IMPLICATIONS FOR NURSING PRACTICE

Nurses at all levels of practice need to be knowledgeable about the various hereditary colorectal cancer syndromes to guide appropriate referral to a genetics professional and to provide appropriate care to these high-risk individuals.

Germline mutation prevalence in individuals with pancreatic cancer and a history of previous malignancy

BACKGROUND

Approximately 10% of pancreatic adenocarcinoma (PC) cases are attributed to hereditary causes. Individuals with PC and a personal history of another cancer associated with hereditary breast and ovarian cancer (HBOC) or Lynch syndrome (LS) may be more likely to carry germline mutations.

METHODS

Participants with PC and a history of cancer were selected from a pancreatic disease registry. Of 1296 individuals with PC, 149 had a relevant history of cancer. If banked DNA was available, a multigene panel was performed for individuals who had not 1) previously had a mutation identified through clinical testing or 2) undergone clinical multigene panel testing with no mutations detected.

RESULTS

Twenty-two of 124 individuals with PC and another HBOC- or LS-related cancer who underwent genetic testing had a mutation identified in a PC susceptibility gene (18%). If prostate cancer is excluded, the mutation prevalence increased to 23% (21/93). Mutation carriers were more likely to have more than 1 previous cancer diagnosis (P = .001), to have had clinical genetic testing (P = .001), and to meet National Comprehensive Cancer Network (NCCN) genetic testing criteria (P < .001). Approximately 23% of mutation carriers did not meet NCCN HBOC or LS testing guidelines based on their personal cancer history and reported cancer history in first-degree relatives.

CONCLUSION

At least 18% of individuals with PC and a personal history of other HBOC- or LS-related cancers carry mutations in a PC susceptibility gene based on our data, suggesting that criteria for genetic testing in individuals with PC should include consideration of previous cancer history. Cancer 2018;124:1691-700. © 2018 American Cancer Society.

Association of monoallelic MUTYH mutation among Egyptian patients with colorectal cancer

Colorectal cancer (CRC) is a heterogeneous triat that involves both environmental and genetic factors. Genetic mutations of MUTYH (p.Y179C and p.G396D) have been reported to be associated with increased risk of CRC among several ethnic populations. The aim of this work is to assess the association of the monoallelic MUTYH mutations (p.Y179C and p.G396D) with increased risk of CRC among Egyptian patients. This study included 120 unrelated CRC Egyptian patients who were compared with 100 healthy controls from the same locality. For all individuals, DNA was genotyped for MUTYH p.Y179C and MUTYH p.G396D mutations using the T-ARMS-PCR technique. The frequencies of monoallelic MUTYH mutations showed a strong association with the increased risk of CRC among Egyptian patients compared with controls (12.5 vs. 4.0 %, OR = 3.49, 95 % CI = 1.12-10.90, P = 0.03). Moreover, the frequency of MUTYH p.Y179C mutation was noted to be significantly higher among CRC patients compared to controls rather than MUTYH p.G396D mutation. Interestingly, CRC patients with tumors in the right side colon showed an evidence for association with the MUTYH p.Y179C mutation compared with tumors in the left side colon (p = 0.01). MUTYH p.Y179C mutation was associated with an increased risk of CRC among Egyptian patients rather than MUTYH p.G396D mutation.

Hereditary Colorectal Tumors: A Literature Review on MUTYH-Associated Polyposis

MAP (MUTYH-associated polyposis) is a syndrome, described in 2002, which is associated with colorectal adenomas, with enhanced colorectal carcinogenesis. This review synthesizes the available literature on MAP and outlines its pathogenesis, association with colorectal tumorigenesis, screening, treatment, and the subtle differences between it and its close cousins—FAP and AFAP. The preponderance of data is collected using MAP guidelines. However, although AFAP and MAP appear similar, potentially important distinctions exist, warranting targeted diagnostic criteria and treatment approaches. We suggest that it may be prudent to screen for MAP earlier than in current clinical practice, as it has been shown that sequence variants are associated with more severe disease, presenting with an earlier onset of colorectal cancer. Finally, we issue a call-to-action for much-needed further data to establish clear clinical and diagnostic criteria.

Genetic predisposition to colorectal cancer: Implications for treatment and prevention

Colorectal cancer (CRC) is the third most common cancer diagnosed in men and women and approximately 5% of cases are associated with identifiable germline mutations associated with hereditary cancer syndromes. Lifetime risks for CRC can approach 50%-80% for mutation carriers in the absence of endoscopic and/or surgical intervention, and early identification of at-risk individuals can guide clinical interventions for cancer prevention and treatment. Personal and family history and molecular phenotype of CRC tumors are used in determining which patients should be referred for clinical genetic evaluation. Outcomes of genetic testing performed using next-generation sequencing (NGS) multigene panels suggest there can be significant overlap in clinical features among the various hereditary cancer syndromes. This review summarizes new developments in diagnosis and management of patients with genetic predisposition to CRC.

Heritable Gastrointestinal Cancer Syndromes

Although almost all gastrointestinal cancers develop from sporadic genomic events, approximately 5% arise from germline mutations in genes associated with cancer predisposition. The number of these genes continues to increase. Tumor phenotypes and family history provide the framework for identifying at-risk individuals. The diagnosis of a hereditary cancer syndrome has implications for management of patients and their families. Systematic approaches that integrate family history and molecular characterization of tumors and polyps facilitate identification of individuals with this genetic predisposition. This article summarizes diagnosis and management of hereditary cancer syndromes associated with gastrointestinal cancers.

Advances in Hereditary Colorectal and Pancreatic Cancers

PURPOSE

Innovations in genetic medicine have led to improvements in the early detection, prevention, and treatment of cancer for patients with inherited risks of gastrointestinal cancer, particularly hereditary colorectal cancer and hereditary pancreatic cancer.

METHODS

This review provides an update on recent data and key advances that have improved the identification, understanding, and management of patients with hereditary colorectal cancer and hereditary pancreatic cancer.

FINDINGS

This review details recent and emerging data that highlight the developing landscape of genetics in hereditary colorectal and pancreatic cancer risk. A summary is provided of the current state-of-the-art practices for identifying, evaluating, and managing patients with suspected hereditary colorectal cancer and pancreatic cancer risk. The impact of next-generation sequencing technologies in the clinical diagnosis of hereditary gastrointestinal cancer and also in discovery efforts of new genes linked to familial cancer risk are discussed. Emerging targeted therapies that may play a particularly important role in the treatment of patients with hereditary forms of colorectal cancer and pancreatic cancer are also reviewed. Current approaches for pancreatic cancer screening and the psychosocial impact of such procedures are also detailed.

IMPLICATIONS

Given the availability of new diagnostic, risk-reducing, and therapeutic strategies that exist for patients with hereditary risk of colorectal or pancreatic cancer, it is imperative that clinicians be vigilant about evaluating patients for hereditary cancer syndromes. Continuing to advance genetics research in hereditary gastrointestinal cancers will allow for more progress to be made in personalized medicine and prevention.

Familial colorectal cancer

Identifying individuals with a genetic predisposition to developing familial colorectal cancer (CRC) is crucial to the management of the affected individual and their family. In order to do so, the physician requires an understanding of the different gene mutations and clinical manifestations of familial CRC. This review summarises the genetics, clinical manifestations and management of the known familial CRC syndromes, specifically Lynch syndrome, familial adenomatous polyposis, MUTYH-associated neoplasia, juvenile polyposis syndrome and Peutz-Jeghers syndrome. An individual suspected of having a familial CRC with an underlying genetic predisposition should be referred to a familial cancer centre to enable pre-test counselling and appropriate follow up.

Molecular Features and Methylation Status in Early Onset (≤40 Years) Colorectal Cancer: A Population Based, Case-Control Study

Colorectal cancer is usually considered a disease of the elderly. However, a small fraction of patients develops colorectal cancer earlier. The aim of our study was to define the frequency of known hereditary colorectal syndromes and to characterise genetic and epigenetic features of early nonhereditary tumors. Thirty-three patients ≤40 years with diagnosis of colorectal cancer and 41 patients with disease at >60 years of age were investigated for MSI, Mismatch Repair proteins expression, KRAS and BRAF mutations, hypermethylation, and LINE-1 hypomethylation. Detection of germline mutations was performed in Mismatch Repair, APC and MUTYH genes. Early onset colorectal cancer showed a high incidence of hereditary forms (18%). KRAS mutations were detected in 36% of early nonhereditary tumors. Early onset colorectal cancer disclosed an average number of methylated genes significantly lower when compared to the controls (p = 0.02). Finally both of the two groups were highly methylated in ESR1, GATA5, and WT1 genes and were similar for LINE-1 hypomethylation. The genetic make-up of carcinomas differs from young to elderly patients. Early onset tumors showed more frequently a constitutional defective of Mismatch Repair System and a minor number of methylated genes. Hypermethylation of ESR1, GATA5, and WT1 genes suggests possible markers in the earlier diagnosis of colorectal tumorigenesis.

Genetics and Genetic Testing in Hereditary Colorectal Cancer

Colorectal cancer (CRC) remains the third most common cancer affecting men and women in the United States. Approximately one-third of CRCs are diagnosed in individuals who have family members also affected with the disease. Although the vast majority of colorectal neoplasms develop as a consequence of somatic genomic alterations arising in individual cells, approximately 5% of all CRCs arise in the setting of germline mutations in genes involved in key cellular processes. To date, multiple genes have been implicated in single-gene hereditary cancer syndromes, many of which are associated with increased risk for CRC, as well as other tumor types. This review outlines the clinical, pathologic, and genetic features of the hereditary cancer syndromes known to be associated with increased risk for CRC and delineates strategies for implementing genetic risk assessments in clinical settings.

Identification of a Variety of Mutations in Cancer Predisposition Genes in Patients With Suspected Lynch Syndrome

BACKGROUND & AIMS

Multigene panels are commercially available tools for hereditary cancer risk assessment that allow for next-generation sequencing of numerous genes in parallel. However, it is not clear if these panels offer advantages over traditional genetic testing. We investigated the number of cancer predisposition gene mutations identified by parallel sequencing in individuals with suspected Lynch syndrome.

METHODS

We performed germline analysis with a 25-gene, next-generation sequencing panel using DNA from 1260 individuals who underwent clinical genetic testing for Lynch syndrome from 2012 through 2013. All patients had a history of Lynch syndrome-associated cancer and/or polyps. We classified all identified germline alterations for pathogenicity and calculated the frequencies of pathogenic mutations and variants of uncertain clinical significance (VUS). We also analyzed data on patients' personal and family history of cancer, including fulfillment of clinical guidelines for genetic testing.

RESULTS

Of the 1260 patients, 1112 met National Comprehensive Cancer Network (NCCN) criteria for Lynch syndrome testing (88%; 95% confidence interval [CI], 86%-90%). Multigene panel testing identified 114 probands with Lynch syndrome mutations (9.0%; 95% CI, 7.6%-10.8%) and 71 with mutations in other cancer predisposition genes (5.6%; 95% CI, 4.4%-7.1%). Fifteen individuals had mutations in BRCA1 or BRCA2; 93% of these met the NCCN criteria for Lynch syndrome testing and 33% met NCCN criteria for BRCA1 and BRCA2 analysis (P = .0017). An additional 9 individuals carried mutations in other genes linked to high lifetime risks of cancer (5 had mutations in APC, 3 had bi-allelic mutations in MUTYH, and 1 had a mutation in STK11); all of these patients met NCCN criteria for Lynch syndrome testing. A total of 479 individuals had 1 or more VUS (38%; 95% CI, 35%-41%).

CONCLUSIONS

In individuals with suspected Lynch syndrome, multigene panel testing identified high-penetrance mutations in cancer predisposition genes, many of which were unexpected based on patients' histories. Parallel sequencing also detected a high number of potentially uninformative germline findings, including VUS.

Screening in GI Cancers: The Role of Genetics

Genetic and epigenetic alterations identified in tumors of different cancer types can provide insights regarding the roles played by different cell signaling pathways in carcinogenesis. Somatic mutation profiles of GI tumors are used to guide choice of chemotherapy and can facilitate identification of individuals whose cancers arise in the setting of genetic predisposition. This review provides a framework for how clinical history, family history of cancer, and tumor genomic phenotype can be used to screen patients with colorectal, gastric, or pancreatic cancer for hereditary cancer syndromes. Early identification of individuals who carry germline mutations can affect clinical care not only for patients with cancer but also for their at-risk relatives.

Somatic c.34G>T KRAS mutation: a new prescreening test for MUTYH-associated polyposis?

We investigated the somatic c.34G>T KRAS transversion as a marker suggestive of MUTYH-associated polyposis (MAP). We compared 86 adenomas and 19 colorectal cancers (CRCs) of 30 MAP patients to 135 adenomas and five CRCs of 47 familial adenomatous polyposis (FAP) patients. The c.34G>T mutation was investigated by DNA sequencing. Secondly, the germline MUTYH gene sequence was analyzed in patients carrying c.34G>T in CRCs diagnosed between 2008 and 2012. The c.34G>T was present in 39.7% of MAP adenomas versus 1.6% of FAP adenomas (P < 0.01). Sensitivity and specificity for detecting MAP were 39.7% and 98%, respectively. Sensitivity increased with the number of adenomas tested (P = 0.039). KRAS exon 2 analysis was performed on 2239 CRC and 2.2% harbored the c.34G>T transversion. Among 28 carriers of the c.34G>T mutation, biallelic MUTYH mutations were detected in seven patients (25%). One patient did not have any polyp or family history and did not fulfill criteria for MUTYH testing. With high specificity, the c.34G>T mutation seems to be a useful and promising test for MAP. For polyposis, it may guide genetic testing toward APC or MUTYH. If routinely performed in CRC patients, it could help to diagnose MUTYH-mutation carriers, even when they don't fulfill genetic testing criteria.

The genetic basis of familial adenomatous polyposis and its implications for clinical practice and risk management

Familial adenomatous polyposis (FAP) is an inherited disorder that represents the most common gastrointestinal polyposis syndrome. Germline mutations in the APC gene were initially identified as responsible for FAP, and later, several studies have also implicated the MUTYH gene as responsible for this disease, usually referred to as MUTYH-associated polyposis (MAP). FAP and MAP are characterized by the early onset of multiple adenomatous colorectal polyps, a high lifetime risk of colorectal cancer (CRC), and in some patients the development of extracolonic manifestations. The goal of colorectal management in these patients is to prevent CRC mortality through endoscopic and surgical approaches. Individuals with FAP and their relatives should receive appropriate genetic counseling and join surveillance programs when indicated. This review is focused on the description of the main clinical and genetic aspects of FAP associated with germline APC mutations and MAP.

Hereditary and common familial colorectal cancer: evidence for colorectal screening

Colorectal cancer (CRC) is the fourth most common cancer among men and women. Between 3 and 6% of all CRCs are attributed to well-defined inherited syndromes, including Lynch syndrome, familial adenomatous polyposis, MUTYH-associated polyposis and several hamartomatous conditions. Up to 30% of CRC cases exhibit common familial risk, likely related to a combination of inherited factors and environment. Identification of these patients through family history and appropriate genetic testing can provide estimates of cancer risk that inform appropriate cancer screening, surveillance and/or preventative interventions. This article examines the colon cancer syndromes, their genetic basis, clinical management and evidence supporting colorectal screening. It also deals with the category of common (non-syndromic) familial risk including risk determination and screening guidelines.

Report from the OECI Oncology Days 2014

The 2014 OECI Oncology Days was held at the 'Prof. Dr. Ion Chiricuta' Oncology Institute in Cluj, Romania, from 12 to 13 June. The focus of this year's gathering was on developments in personalised medicine and other treatment advances which have made the cost of cancer care too high for many regions throughout Europe.

Colorectal carcinogenesis-update and perspectives

Colorectal cancer (CRC) is a very common malignancy in the Western World and despite advances in surgery, chemotherapy and screening, it is still the second leading cause of cancer deaths in this part of the world. Numerous factors are found important in the development of CRC including colonocyte metbolism, high risk luminal environment, inflammation, as well as lifestyle factors such as diet, tobacco, and alchohol consumption. In recent years focus has turned towards the genetics and molecular biology of CRC and several interesting and promising correlations and pathways have been discovered. The major genetic pathways of CRC are the Chromosome Instability Pathway representing the pathway of sporadic CRC through the K-ras, APC, and P53 mutations, and the Microsatellite Instability Pathway representing the pathway of hereditary non-polyposis colon cancer through mutations in mismatch repair genes. To identify early cancers, screening programs have been initiated, and the leading strategy has been the use of faecal occult blood testing followed by colonoscopy in positive cases. Regarding the treatment of colorectal cancer, significant advances have been made in the recent decade. The molecular targets of CRC include at least two important cell surface receptors: the epidermal growth factor receptor and the vascular endothelial growth factor receptor. The genetic and molecular knowledge of CRC has widen the scientific and clinical perspectives of diagnosing and treatment. However, despite significant advances in the understanding and treatment of CRC, results from targeted therapy are still not convincing. Future studies will determine the role for this new treatment modality.

Hereditary colorectal cancer syndromes: American Society of Clinical Oncology Clinical Practice Guideline endorsement of the familial risk-colorectal cancer: European Society for Medical Oncology Clinical Practice Guidelines

PURPOSE

To provide recommendations on prevention, screening, genetics, treatment, and management for people at risk for hereditary colorectal cancer (CRC) syndromes. The American Society of Clinical Oncology (ASCO) has a policy and set of procedures for endorsing clinical practice guidelines that have been developed by other professional organizations.

METHODS

The Familial Risk-Colorectal Cancer: European Society for Medical Oncology Clinical Practice Guideline published in 2013 on behalf of the European Society for Medical Oncology (ESMO) Guidelines Working Group in Annals of Oncology was reviewed for developmental rigor by methodologists, with content and recommendations reviewed by an ASCO endorsement panel.

RESULTS

The ASCO endorsement panel determined that the recommendations of the ESMO guidelines are clear, thorough, and based on the most relevant scientific evidence. The ASCO panel endorsed the ESMO guidelines and added a few qualifying statements.

RECOMMENDATIONS

Approximately 5% to 6% of patient cases of CRC are associated with germline mutations that confer an inherited predisposition for cancer. The possibility of a hereditary cancer syndrome should be assessed for every patient at the time of CRC diagnosis. A diagnosis of Lynch syndrome, familial adenomatous polyposis, or another genetic syndrome can influence clinical management for patients with CRC and their family members. Screening for hereditary cancer syndromes in patients with CRC should include review of personal and family histories and testing of tumors for DNA mismatch repair deficiency and/or microsatellite instability. Formal genetic evaluation is recommended for individuals who meet defined criteria.

A practice guideline from the American College of Medical Genetics and Genomics and the National Society of Genetic Counselors: referral indications for cancer predisposition assessment

DISCLAIMER

The practice guidelines of the American College of Medical Genetics and Genomics (ACMG) and the National Society of Genetic Counselors (NSGC) are developed by members of the ACMG and NSGC to assist medical geneticists, genetic counselors, and other health-care providers in making decisions about appropriate management of genetic concerns, including access to and/or delivery of services. Each practice guideline focuses on a clinical or practice-based issue and is the result of a review and analysis of current professional literature believed to be reliable. As such, information and recommendations within the ACMG and NSGC joint practice guidelines reflect the current scientific and clinical knowledge at the time of publication, are current only as of their publication date, and are subject to change without notice as advances emerge. In addition, variations in practice, which take into account the needs of the individual patient and the resources and limitations unique to the institution or type of practice, may warrant approaches, treatments, and/or procedures that differ from the recommendations outlined in this guideline. Therefore, these recommendations should not be construed as dictating an exclusive course of management, nor does the use of such recommendations guarantee a particular outcome. Genetic counseling practice guidelines are never intended to displace a health-care provider's best medical judgment based on the clinical circumstances of a particular patient or patient population. Practice guidelines are published by the ACMG or the NSGC for educational and informational purposes only, and neither the ACMG nor the NSGC "approve" or "endorse" any specific methods, practices, or sources of information.Cancer genetic consultation is an important aspect of the care of individuals at increased risk of a hereditary cancer syndrome. Yet several patient, clinician, and system-level barriers hinder identification of individuals appropriate for cancer genetics referral. Thus, the purpose of this practice guideline is to present a single set of comprehensive personal and family history criteria to facilitate identification and maximize appropriate referral of at-risk individuals for cancer genetic consultation. To develop this guideline, a literature search for hereditary cancer susceptibility syndromes was conducted using PubMed. In addition, GeneReviews and the National Comprehensive Cancer Network guidelines were reviewed when applicable. When conflicting guidelines were identified, the evidence was ranked as follows: position papers from national and professional organizations ranked highest, followed by consortium guidelines, and then peer-reviewed publications from single institutions. The criteria for cancer genetic consultation referral are provided in two formats: (i) tables that list the tumor type along with the criteria that, if met, would warrant a referral for a cancer genetic consultation and (ii) an alphabetical list of the syndromes, including a brief summary of each and the rationale for the referral criteria that were selected. Consider referral for a cancer genetic consultation if your patient or any of their first-degree relatives meet any of these referral criteria.

Familial colorectal cancer, beyond Lynch syndrome

Although 30% of individuals diagnosed with colorectal cancer (CRC) report a family history of the disease, only 5% to 6% carry germline mutations in genes associated with known hereditary cancer syndromes. The evaluation and management of families affected with CRC can be complicated by variability in disease phenotypes and limited sensitivity of genetic tests. In this review, we examine what is currently known about familial CRC and what we have yet to learn, and explore how novel genomic approaches might be used to identify additional genetic and epigenetic factors implicated in heritable risk for cancer.

Prevalence of germline MUTYH mutations among Lynch-like syndrome patients

BACKGROUND AND AIMS

Individuals with tumours showing mismatch repair (MMR) deficiency not linked to germline mutations or somatic methylation of MMR genes have been recently referred as having 'Lynch-like syndrome' (LLS). The genetic basis of these LLS cases is unknown. MUTYH-associated polyposis patients show some phenotypic similarities to Lynch syndrome patients. The aim of this study was to investigate the prevalence of germline MUTYH mutations in a large series of LLS patients.

METHODS

Two hundred and twenty-five probands fulfilling LLS criteria were included in this study. Screening of MUTYH recurrent mutations, whole coding sequencing and a large rearrangement analysis were undertaken. Age, sex, clinical, pathological and molecular characteristics of tumours including KRAS mutations were assessed.

RESULTS

We found a prevalence of 3.1% of MAP syndrome in the whole series of LLS (7/225) and 3.9% when only cases fulfilling clinical criteria were considered (7/178). Patients with MUTYH biallelic mutations had more adenomas than monoallelic (P=0.02) and wildtype patients (P<0.0001). Six out of nine analysed tumours from six biallelic MUTYH carriers harboured KRAS-p.G12C mutation. This mutation was found to be associated with biallelic MUTYH germline mutation when compared with reported series of unselected colorectal cancer cohorts (P<0.0001).

CONCLUSIONS

A proportion of unexplained LLS cases is caused by biallelic MUTYH mutations. The obtained results further justify the inclusion of MUTYH in the diagnostic strategy for Lynch syndrome-suspected patients.

Clinical characterization and mutation spectrum in Hispanic families with adenomatous polyposis syndromes

Several genetically defined hereditary colorectal cancer (CRC) syndromes are associated with colonic polyposis including familial adenomatous polyposis (FAP) and MUTYH adenomatous polyposis (MAP). Limited data exists on the clinical characterization and genotypic spectrum of polyposis syndromes among Hispanics. To describe the phenotype and genotype of Puerto Rican Hispanic patients with FAP and MUTYH and compare with other ethnic and racial groups. Probands were identified from the Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR). Recruited individuals completed risk factors, medical, and family history questionnaires and underwent genetic testing for genotype analysis. Frequency analysis, Chi square, Fisher's exact and Wilcoxon rank-sum tests were used for statistical analysis methods. A total of 31 FAP (from 19 families) and 13 MAP (from 13 families) Hispanic patients recruited from the PURIFICAR were evaluated. Among the FAP cases, mean age at diagnosis was 27.6 (range 9-71 years); 67.7 % cases had more than 100 polyps and 41.9 % had upper gastrointestinal polyps. Among the 19 FAP families, there were 77 affected FAP individuals and 26 colorectal cancer cases. Genetic mutations were available for 42.2 % of FAP families; all mutations identified were unique. Surgeries were reported in 31 cases; 14 (45.2 %) prophylactic surgeries and 6 (19.4 %) therapeutic surgeries for management of CRC. Among MAP cases, mean age at diagnosis was 53 (range 34-76 years). Genetic analysis revealed homozygous biallelic mutations (G382D) in 53.8 %, compound heterozygous mutations (G382/Y165C) in 23 %, and non-G382/Y165C monoallelic mutations in 23 %. Familial cancer registries should be promoted as vehicles for detection, education and follow up of families at-risk of acquiring familial cancers. PURIFICAR is the first and only familial cancer registry in Puerto Rico providing these services to families affected with familial cancer syndromes promoting education, testing and surveillance of at-risk family members, and focusing on cancer prevention efforts. The fact that only 40 % of FAP patients had access to genetic testing stresses the need to promote the establishment of policies supporting genetic testing coverage by medical insurance companies in order to provide patients with the highest standard of care to prevent cancer. Furthermore, our results suggest that Hispanics may have uncommon mutations in adenomatous polyposis related genes, which emphasize the need for full gene sequencing to establish genetic diagnosis.

Analysis of current testing practices for biallelic MUTYH mutations in MUTYH-associated polyposis

MUTYH-associated polyposis (MAP) is an autosomal recessive syndrome caused by biallelic mutations in the base excision repair gene MUTYH. Owing to potential limitations in the MAP testing strategy and testing criteria, it is possible that MAP is being under-identified both genotypically and phenotypically. To determine whether full sequencing of MUTYH would increase clinical sensitivity over a founder mutation (FM) strategy, a retrospective analysis of two datasets from a commercial clinical laboratory was performed. The first cohort contained 1522 individuals who received MUTYH analysis for two FMs with subsequent full-gene sequencing. Eighty-five biallelic individuals were identified; 47 carried two FMs, 17 carried one FM and one mutation identified on full sequencing, and 21 carried biallelic mutations identified only on full sequencing. The second cohort contained 921 patients with colorectal cancer <50 years and <10 reported colorectal adenomas who had undergone MUTYH mutation testing. In this cohort, 19 of 921 (2.1%) individuals were identified as biallelic MUTYH carriers. Of these, 13 did not have a personal or family history of polyps and would not have met guidelines for MUTYH testing. These results suggest that individuals with biallelic MUTYH mutations are under-ascertained based on both genotype and phenotype under current standard testing practices.

Risk of colorectal cancer for carriers of mutations in MUTYH, with and without a family history of cancer

We studied 2332 individuals with monoallelic mutations in MUTYH among 9504 relatives of 264 colorectal cancer (CRC) cases with a MUTYH mutation. We estimated CRC risks through 70 years of age of 7.2% for male carriers of monoallelic mutations (95% confidence interval [CI], 4.6%-11.3%) and 5.6% for female carriers of monoallelic mutations (95% CI, 3.6%-8.8%), irrespective of family history. For monoallelic MUTYH mutation carriers with a first-degree relative with CRC diagnosed by 50 years of age who does not have the MUTYH mutation, risks of CRC were 12.5% for men (95% CI, 8.6%-17.7%) and 10% for women (95% CI, 6.7%-14.4%). Risks of CRC for carriers of monoallelic mutations in MUTYH with a first-degree relative with CRC are sufficiently high to warrant more intensive screening than for the general population.

Multiple sporadic colorectal cancers display a unique methylation phenotype

Epigenetics are thought to play a major role in the carcinogenesis of multiple sporadic colorectal cancers (CRC). Previous studies have suggested concordant DNA hypermethylation between tumor pairs. However, only a few methylation markers have been analyzed. This study was aimed at describing the epigenetic signature of multiple CRC using a genome-scale DNA methylation profiling. We analyzed 12 patients with synchronous CRC and 29 age-, sex-, and tumor location-paired patients with solitary tumors from the EPICOLON II cohort. DNA methylation profiling was performed using the Illumina Infinium HM27 DNA methylation assay. The most significant results were validated by Methylight. Tumors samples were also analyzed for the CpG Island Methylator Phenotype (CIMP); KRAS and BRAF mutations and mismatch repair deficiency status. Functional annotation clustering was performed. We identified 102 CpG sites that showed significant DNA hypermethylation in multiple tumors with respect to the solitary counterparts (difference in β value ≥0.1). Methylight assays validated the results for 4 selected genes (p = 0.0002). Eight out of 12(66.6%) multiple tumors were classified as CIMP-high, as compared to 5 out of 29(17.2%) solitary tumors (p = 0.004). Interestingly, 76 out of the 102 (74.5%) hypermethylated CpG sites found in multiple tumors were also seen in CIMP-high tumors. Functional analysis of hypermethylated genes found in multiple tumors showed enrichment of genes involved in different tumorigenic functions. In conclusion, multiple CRC are associated with a distinct methylation phenotype, with a close association between tumor multiplicity and CIMP-high. Our results may be important to unravel the underlying mechanism of tumor multiplicity.

Hereditary colorectal cancer syndromes

SUMMARY Colorectal cancer (CRC) is one of the most common malignancies and the second-leading cause of cancer death in both sexes in developed countries. Over the last 25 years, highly penetrant monogenic germline mutations that predispose to CRC and other digestive tumors have been identified, accounting for up to 5% of all CRC cases. Identification and characterization of these disorders have allowed modification of their natural history, with a substantial decrease in morbidity and mortality among high-risk patients. Recognizing hereditary CRC has also impacted predictive genetic testing and personalized medicine based on genomic information. This review summarizes the current knowledge on hereditary CRC regarding pathogenesis, clinical features, diagnostic evaluation and management recommendations.

Prevalence and characteristics of MUTYH-associated polyposis in patients with multiple adenomatous and serrated polyps

PURPOSE

The present study aimed to determine the prevalence of MUTYH mutations in patients with multiple colonic polyps and to explore the best strategy for diagnosing MUTYH-associated polyposis (MAP) in these patients.

EXPERIMENTAL DESIGN

This study included 405 patients with at least 10 colonic polyps each. All cases were genetically tested for the three most frequent MUTYH mutations. Whole-gene analysis was performed in heterozygous patients and in 216 patients lacking the three most frequent mutations. Polyps from 56 patients were analyzed for the KRAS-Gly12Cys and BRAF V600E somatic mutations.

RESULTS

Twenty-seven (6.7%) patients were diagnosed with MAP, of which 40.8% showed serrated polyps. The sensitivity of studying only the three common variants was 74.1%. Of 216 patients without any monoallelic mutation in common variants, whole-gene analysis revealed biallelic pathogenic mutation in only one. G396D mutation was associated with serrated lesions and older age at diagnosis. There was a strong association between germinal MUTYH mutation and KRAS Gly12Cys somatic mutation in polyps. BRAF V600E mutation was found in 74% of serrated polyps in MUTYH-negative patients and in none of the polyps of MAP patients.

CONCLUSIONS

We observed a low frequency of MUTYH mutations among patients with multiple adenomatous and serrated polyps. The MAP phenotype frequently included patients with serrated polyps, especially when G396D mutation was involved. Our results show that somatic molecular markers of polyps can be useful in identifying MAP cases and support the need for the complete MUTYH gene analysis only in patients heterozygous for recurrent variants.