A prospective study of the clinical, genetic, screening, and pathologic features of a family with hereditary mixed polyposis syndrome

Genetic Predisposition to Colorectal Cancer: How Many and Which Genes to Test?

Colorectal cancer is one of the most common tumors, and genetic predisposition is one of the key risk factors in the development of this malignancy. Lynch syndrome and familial adenomatous polyposis are the best-known genetic diseases associated with hereditary colorectal cancer. However, some other genetic disorders confer an increased risk of colorectal cancer, such as Li-Fraumeni syndrome (TP53 gene), MUTYH-associated polyposis (MUTYH gene), Peutz-Jeghers syndrome (STK11 gene), Cowden syndrome (PTEN gene), and juvenile polyposis syndrome (BMPR1A and SMAD4 genes). Moreover, the recent advances in molecular techniques, in particular Next-Generation Sequencing, have led to the identification of many new genes involved in the predisposition to colorectal cancers, such as RPS20, POLE, POLD1, AXIN2, NTHL1, MSH3, RNF43 and GREM1. In this review, we summarized the past and more recent findings in the field of cancer predisposition genes, with insights into the role of the encoded proteins and into the associated genetic disorders. Furthermore, we discussed the possible clinical utility of genetic testing in terms of prevention protocols and therapeutic approaches.

Update on genetic predisposition to colorectal cancer and polyposis

The present article summarizes recent developments in the characterization of genetic predisposition to colorectal cancer (CRC). The main themes covered include new hereditary CRC and polyposis syndromes, non-CRC hereditary cancer genes found mutated in CRC patients, strategies used to identify novel causal genes, and review of candidate genes that have been proposed to predispose to CRC and/or colonic polyposis. We provide an overview of newly described genes and syndromes associated with predisposition to CRC and polyposis, including: polymerase proofreading-associated polyposis, NTHL1-associated polyposis, mismatch repair gene biallelic inactivation-related adenomatous polyposis (including MSH3- and MLH3-associated polyposes), GREM1-associated mixed polyposis, RNF43-associated serrated polyposis, and RPS20 mutations as a rare cause of hereditary nonpolyposis CRC. The implementation of next generation sequencing approaches for genetic testing has exposed the presence of pathogenic germline variants in genes associated with hereditary cancer syndromes not traditionally linked to CRC, which may have an impact on genetic testing, counseling and surveillance. The identification of new hereditary CRC and polyposis genes has not deemed an easy endeavor, even though known CRC-related genes explain a small proportion of the estimated familial risk. Whole-genome sequencing may offer a technology for increasing this proportion, particularly if applied on pedigree data allowing linkage type of analysis. The final section critically surveys the large number of candidate genes that have been recently proposed for CRC predisposition.

Inherited Cancer in the Age of Next-Generation Sequencing

Next-generation sequencing (NGS) technology has led to the ability to test for multiple cancer susceptibility genes simultaneously without significantly increasing cost or turnaround time. With growing usage of multigene testing for inherited cancer, ongoing education for nurses and other health-care providers about hereditary cancer screening is imperative to ensure appropriate testing candidate identification, test selection, and posttest management. The purpose of this review article is to (1) provide an overview of how NGS works to detect germline mutations, (2) summarize the benefits and limitations of multigene panel testing, (3) describe risk categories of cancer susceptibility genes, and (4) highlight the counseling considerations for patients pursuing multigene testing.

Features of Patients With Hereditary Mixed Polyposis Syndrome Caused by Duplication of GREM1 and Implications for Screening and Surveillance

Hereditary mixed polyposis syndrome is a rare colon cancer predisposition syndrome caused by a duplication of a noncoding sequence near the gremlin 1, DAN family BMP antagonist gene (GREM1) originally described in Ashkenazi Jews. Few families with GREM1 duplications have been described, so there are many questions about detection and management. We report 4 extended families with the duplication near GREM1 previously found in Ashkenazi Jews; 3 families were identified at cancer genetic clinics in Israel and 1 family was identified in a cohort of patients with familial colorectal cancer. Their clinical features include extracolonic tumors, onset of polyps in adolescence, and rapid progression of some polyps to advanced adenomas. One family met diagnostic criteria for Lynch syndrome. Expansion of the hereditary mixed polyposis syndrome phenotype can inform surveillance strategies for carriers of GREM1 duplications.

Reprint of: the natural history of adenomas

It is well known that adenomas represent the morphologically categorised precursor of the vast majority of colorectal cancers. Only few adenomas actually develop invasive cancer (progressive adenomas), although every adenoma has the capacity of malignant evolution. Most adenomas stabilise their progression or even regress. Easily identifiable but widely ranged pathological features (size, architectural growth, type, grade and gross organisation of dysplasia) are predictive of their natural history in terms of potential of cancerisation and duration of the adenoma-carcinoma sequence. Knowledge of the biological machineries sustaining the progression rates and times could be crucial to refine the natural history assumptions in screening modelling.

The natural history of adenomas

It is well known that adenomas represent the morphologically categorised precursor of the vast majority of colorectal cancers. Only few adenomas actually develop invasive cancer (progressive adenomas), although every adenoma has the capacity of malignant evolution. Most adenomas stabilise their progression or even regress. Easily identifiable but widely ranged pathological features (size, architectural growth, type, grade and gross organisation of dysplasia) are predictive of their natural history in terms of potential of cancerisation and duration of the adenoma-carcinoma sequence. Knowledge of the biological machineries sustaining the progression rates and times could be crucial to refine the natural history assumptions in screening modelling.

Genetics of the hamartomatous polyposis syndromes: a molecular review

BACKGROUND AND AIMS

Hamartomatous polyposis syndromes are a heterogeneous group of disorders that are inherited in an autosomal dominant fashion. These syndromes only represent a small number of the inherited gastrointestinal cancer predisposition syndromes. However, many of these syndromes carry a substantial risk for developing colorectal cancer, as well as extra-colonic malignancy.

MATERIALS AND METHODS

We searched for articles on inherited hamartomatous polyposis syndromes, including familial juvenile polyposis syndrome, Peutz-Jeghers syndrome, PTEN hamartoma tumor syndrome, multiple endocrine neoplasia syndrome 2B, hereditary mixed polyposis syndrome, Cronkhite-Canada syndrome, basal cell nevus syndrome, and neurofibromatosis 1, in PubMed, Embase, and Elsevier ScienceDirect. In this review, we briefly discuss the diagnosis and clinical features of these disorders and the molecular alterations responsible for these syndromes.

RESULTS AND CONCLUSION

Given the clinical similarities of these hamartomatous syndromes and the autosomal dominant pattern of inheritance, it is sometimes difficult to differentiate hamartomatous polyps, especially with atypical presentation. The molecular analysis and diagnosis make it possible to identify the subtype of these syndromes. In addition, these tests raise an intriguing possibility that surveillance and early medical intervention will allow for the identification of at-risk patients and the reduction of morbidity and mortality.

Hamartomatous polyposis syndromes

Since the histologic description of the hamartomatous polyp in 1957 by Horrilleno and colleagues, descriptions have appeared of several different syndromes with the propensity to develop these polyps in the upper and lower gastrointestinal tracts. These syndromes include juvenile polyposis, Peutz-Jeghers syndrome, hereditary mixed polyposis syndrome, and the phosphatase and tensin homolog gene (PTEN) hamartoma tumor syndromes (Cowden and Bannayan-Riley-Ruvalcaba syndromes), which are autosomal-dominantly inherited, and Cronkhite-Canada syndrome, which is acquired. This article reviews the clinical aspects, the molecular pathogenesis, the affected organ systems, the risks of cancer, and the management of these hamartomatous polyposis syndromes. Although the incidence of these syndromes is low, it is important for clinicians to recognize these disorders to prevent morbidity and mortality in these patients, and to perform presymptomatic testing in patients at risk.

Pathology of the hereditary colorectal carcinoma

Positive familial history (first or second degree relative) for colorectal carcinoma (CRC) can be found in approximately 30% of all newly diagnosed cases, but less than 5% will be due to a defined genetic category of hereditary CRC. Pathologic examination of the biopsy or resection specimen can help in identification of unsuspected cases of certain forms of hereditary CRC due to the characteristic morphologic findings. Additional immunohistochemical and molecular studies can then provide a definitive diagnosis. The most common form of hereditary CRC is Lynch syndrome (hereditary non-polyposis colorectal cancer, HNPCC) which is characterized by proximally located tumors frequently showing mucinous and medullary type histologic features. The syndrome results from a germline mutation in genes for mismatch repair (MMR) proteins leading to insufficient DNA repair and development of tumors characterized by high levels of instability in short tandem repeat DNA sequences (microsatellites) or "microsatellite instability-high" (MSI-H). The presence of intra-epithelial lymphocytes is single most helpful morphologic feature in identification of CRC caused by deficiency in MMR proteins, for which MSI-H status is a good marker but morphologic features and MSI-H do not differentiate tumors caused by germline mutations in one of the MMR genes (Lynch syndrome) from sporadic CRC due to inactivation of MLH-1 through promoter methylation. Hereditary CRC may also arise in various familial polyposis syndromes which include familial adenomatous polyposis (FAP), attenuated FAP and other multiple adenomas syndromes as well as various hamartomatous polyposis syndromes. All of these rare conditions have characteristic clinical presentation and histopathologic features of polyps and most of them have defined genetic abnormality. Furthermore, due to the germline nature of mutations in these syndromes, various extracolonic manifestations may be the first sign of the disease and knowledge of such associations can greatly improve the quality of care for these patients. The role of pathologist is to recognize these characteristics and initiate appropriate follow up with clinicians and genetic counselors.

Familial adenomatous polyposis: The practical applications of clinical and molecular screening

Familial adenomatous polyposis (FAP) is an autosomal dominant condition mostly due to a mutation of the APC gene on the chromosome 5q. Carriers have an almost 100% chance of developing colorectal cancer after having multiple (typically 100s to 1000s) of adenomatous polyps. It is usually readily identified through this phenotype of multiple adenomas. Correlations between the location of the family-specific mutation on the APC gene and clinical manifestations of the disease are of some assistance in clinical management, though there is heterogeneity in clinical course even between family members with the same mutation. FAP is important to recognize, as there are disease-specific management implications with respect to offering mutational analysis of the APC (and perhaps other) genes for predictive testing of other family members, endoscopic diagnostic procedures, surveillance planning, and surgical management. Extra-colonic manifestations, including duodenal polyposis, desmoid disease and other tumours, can dominate clinical care after colectomy. The inheritable and lethal nature of the disease, together with the availability of effective treatment strategies, makes a sensitive clinical and psychosocial approach important to maximize compliance and good outcomes for all members of affected families.

[Serrated neoplasia of the gastro-intestinal tract]

Serrated neoplasia of the gastro-intestinal tract have peculiar microscopic and molecular features that are still incompletely described. Some serrated polyps seem to be involved in a new carcinogenic pathway in the colon: the serrated neoplasia pathway, with hypermethylation of the cytosine-guanine dinucleotides, located in the promoter of some genes such as h-MLH1, BRAF and MGMT. The natural history of the serrated polyps and their risk for progression to malignancy are still unclear. There is no official guideline for the management of serrated polyps. The aim of this article is to describe the epidemiological, morphological, immunohistochemical and molecular characteristics of the serrated neoplasia of the gastrointestinal tract: hyperplastic polyps, "traditional" serrated adenomas, mixed hyperplastic and adenomatous polyps, sessile serrated adenomas, hyperplastic polyposis and serrated adenocarcinomas.

Trends in colorectal cancer incidence and mortality in the Israeli Jewish ethnic populations

BACKGROUND

Ashkenazi Jews, as compared to non-European Jews and non-Jews, are at increased risk for colorectal cancer (CRC), this is attributed to genetic susceptibility and/or lifestyle.

AIMS

To follow Israeli long-term trends in CRC incidence and mortality and their associations with ethnicity.

METHODS

All Israeli CRC data accumulated 1970-2001 was used, age standardized rates (adjusted to world standard population) was computed by cancer site, US Surveillance, Epidemiology and End Results Program (SEER) Stage and ethnic group (continent of birth: Europe-America, Asia, Africa, Israel).

RESULTS

From 1970, CRC incidence increased 190% in males and 140% in females; mainly colon cancer (270% and 185% respectively) (P < 0.01), while rectal cancer incidence decreased and is now stable. Stage 3 CRC increased while stage 4 decreased significantly (P < 0.01 for both). In 2001, CRC incidence per 100,000 in European-American-born males was 48.3, Asian and African born 35.5 and Israeli born 32.7 (relative risk (RR) 1.36, P = 0.03), while European-American female rates were 35 and all the others 26 (RR 1.35, P < 0.01). Overall survival increased 9% over 30 years (P < 0.01), 5 years survival since 1988-1996 for European-American born was 43.1%, Asian 46.7%, African 47.5% and Israeli 55.8%. Stage-2 CRC 5 years survivals for 1970-1996 (most had no post surgical treatment) for European-American born were 41.7%, Asian and African 44.8% and Israeli 53.4% (P < 0.05). Stage-3 CRC survivals (most received adjuvant therapy in addition to surgery) for European-American born was 38.8%, Asian and African 43.3% and Israeli 45.1% (P < 0.01).

CONCLUSIONS

Colon cancer has increased in Israel, mainly in males and European-American born. Israeli-born Jews (of 20 to 60% mixed ethnicity and lifestyle habits) have the lowest incidence and best survival data for stages-2 and -3 CRC. There is evidence of ethnic survival advantage and possibly in response to adjuvant oncological therapy.

The Jewish people: their ethnic history, genetic disorders and specific cancer susceptibility

The Jews are an ancient and unique group of people linked by language, religion and customs in spite of their major geographical shifts, expulsions, forced conversions and massacres throughout their entire history. As a result of these historical events that led to repeated migration, the Jewish people became dispersed into various ethnic sub-groups. Between these ethnic groups exists heterogeneity, as well as some similarities, to the populations amongst whom they lived. Rare genetic diseases have been reported to be prevalent among the different groups of Jews, which for the most part can be explained by random genetic drift together with intra-familial marriages. In this publication, we will briefly discuss the origin of the various ethnic groups and some of the genetic diseases commonly found in them, with emphasis on the Ashkenazim, their prevalent genetic diseases and cancer susceptibility.

Cyclooxygenase-2 expression in the hereditary mixed polyposis syndrome

Hereditary mixed polyposis syndrome (HMPS), characterized by hyperplastic, juvenile, admixed, serrated adenomas and eventually colorectal cancer, is managed by repeated polypectomy and surgery. We determined if HMPS polyps express cyclooxygenase-2 (COX-2). Nineteen recent HMPS polyps, from five family members, were stained for COX-2. Polyps' epithelium and stroma and comparison tissues (normal colonic mucosa [9], sporadic juvenile polyps [18], colorectal cancers [3]) were quantified for COX-2 by: area of staining (0-3) x intensity (0-3). Epithelial, stromal, and total scores were evaluated in relationship to histology and dysplasia. HMPS polyps COX-2 mean epithelial (5.0+/-3.0), stromal (6.9+/-1.9), and total (11.8+/-4.6) scores were significantly higher (P < 0.01) than sporadic juvenile polyps (0.6+/-0.7, 3.1+/-2.2, and 3.6+/- 2.2 respectively), while colorectal cancer scored 9, 9, and 18. There was a positive association (P < 0.01) among histology, degree of dysplasia, and COX-2 expression. COX-2 expression in HMPS polyps and its association with dysplasia suggest that chemoprevention might be a useful adjunct therapy.