Attenuated familial adenomatous polyposis (AFAP). A review of the literature

Screening and Surveillance of Colorectal Cancer: A Review of the Literature

Colorectal cancer (CRC) has the highest mortality rate among men and is the second highest among women under fifty, with incidence and mortality rates rising in younger populations. Studies indicate that up to one-third of patients diagnosed before fifty have a family history or genetic factors, highlighting the need for earlier screening. Contrariwise, diagnosis in healthy subjects through screening strategies enables early-stage detection of the tumor and better clinical outcomes. In recent years, mortality rates of CRC in Western countries have been on a steady decline, which is largely attributed to widespread screening programs and advancements in treatment modalities. Indeed, early detection through screening significantly improves prognosis, with stark differences in survival rates between localized and metastatic disease. This article aims to provide a comprehensive review of the existing literature, delving into the performance and efficacy of various CRC screening strategies. It navigates through available screening tools, evaluating their efficacy and cost-effectiveness. The discussion extends to delineating target populations for screening, emphasizing the importance of tailored approaches for individuals at heightened risk.

Clinical features and distribution of the APC variant in duodenal and ampullary polyps in patients with familial adenomatous polyposis: a multicenter retrospective cohort study in Japan

BACKGROUND

Management of duodenal or ampullary adenomas in patients with familial adenomatous polyposis (FAP) is a major challenge for clinicians. Insufficient data are available to evaluate the clinical manifestations and distribution of adenomatous polyposis coli (APC) variants in these patients.

METHODS

We enrolled 451 patients with data regarding duodenal or ampullary polyps from 632 patients with FAP retrospectively registered in a nationwide Japanese multicenter study. Clinicopathological features and distribution of APC variants were compared between patients with and without duodenal or ampullary polyps.

RESULTS

Duodenal and ampullary polyps were found in 59% and 18% of patients with FAP, respectively. The incidence of duodenal cancer was 4.7% in patients with duodenal polyps, and that of ampullary cancer was 18% in patients with ampullary polyps. Duodenal polyps were significantly associated with the presence of ampullary polyps and jejunal/ileal polyps. Duodenal polyps progressed in 35% of patients with a median follow-up of 776 days, mostly in those with early Spigelman stage lesions. Ampullary polyps progressed in 50% of patients with a follow-up of 1484 days. However, only one patient developed a malignancy. The proportion of patients with duodenal polyps was significantly higher among those with intermediate- or profuse-type APC variants than attenuated-type APC variants. The presence of duodenal polyps was significantly associated with ampullary and jejunal/ileal polyps in patients with intermediate- or profuse-type APC variants.

CONCLUSIONS

Periodic endoscopic surveillance of the papilla of Vater and small intestine should be planned for patients with FAP with duodenal polyps.

Gastrointestinal Malignancy: Genetic Implications to Clinical Applications

Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.

Low adenoma burden in unselected patients with a pathogenic APC variant

PURPOSE

Genomic screening can improve clinical outcomes, but presentation of individuals with risk for polyposis identified via genomic screening is unknown. To inform assessment of clinical utility of genomic screening for polyposis risk, clinical presentation of individuals in an unselected health care system cohort with an APC pathogenic or likely pathogenic (P/LP) variant causative of familial adenomatous polyposis are described.

METHODS

Electronic health records of individuals with an APC P/LP variant identified via the MyCode program (MyCode APC+) were reviewed to assess adenoma burden and compare it among individuals with a clinical diagnosis of familial adenomatous polyposis and matched variant-negative controls.

RESULTS

The prevalence of APC P/LP variants in this health care cohort is estimated to be 1 in 2800. Twenty-four MyCode APC+ individuals were identified during the study period. Median age at result disclosure was 53 years. Rate of clinical polyposis was 8%. Two of six participants with a classic region variant and none of those with an attenuated region variant had polyposis. MyCode APC+ participants did not differ from controls in cumulative adenoma count.

CONCLUSION

APC P/LP variant prevalence estimate in the MyCode cohort is higher than prior published prevalence rates. Individuals with APC P/LP variants identified via genomic screening had a low adenoma burden.

A case of attenuated familial adenomatous polyposis in which genetic testing revealed that the children were asymptomatic gene carriers

Attenuated familial adenomatous polyposis, which accounts for ~10% of familial adenomatous polyposis, is difficult to diagnose because of its milder course and later onset. In both familial adenomatous polyposis and attenuated familial adenomatous polyposis, duodenal cancer is usually recognized 10-20 years after the diagnosis of colonic polyposis. We present herein a 66-year-old man who received pancreaticoduodenectomy due to ampullary carcinoma 17 years before onset of colonic polyposis. He then received extended right hemicolectoy for ascending colon cancer and ⁓100 polyps located from ceacum to splenic flexure of colon 2 years ago. The patient received Adenomatous polyposis coli (APC) genetic testing and detected a germline pathogenic frameshift variant in the APC gene (NM_000038.6:c.4875delA, ClinVar variant ID (127299)). The variant is classified as likely pathogenic according to the American College of Medical Genetics and Genomics guidelines. APC genetic testing was subsequently performed on his younger children (30 and 26 year old) and they found a same frameshift variant as his father. They were not detected any colonic polyposis by colonoscopy. This is a rare case report of attenuated familial adenomatous polyposis that diagnosed with gastric and colon polyposis >10 years after the diagnosis of ampullary carcinoma and the first report of genetic diagnosis of an attenuated familial adenomatous polyposis variant in young relatives before the onset of the disease.

Hereditary cancer variants and homologous recombination deficiency in biliary tract cancer

BACKGROUND & AIMS

The heritability and actionability of variants in homologous recombination-related genes in biliary tract cancers (BTCs) are uncertain. Although associations between BTC and BRCA germline variants have been reported, homologous recombination deficiency has not been investigated in BTCs.

METHODS

We sequenced germline variants in 27 cancer-predisposing genes in 1,292 BTC cases and 37,583 controls without a personal nor family history of cancer. We compared pathogenic germline variant frequencies between cases and controls and documented the demographic and clinical characteristics of carriers. In addition, whole-genome sequencing of 45 BTC tissues was performed to evaluate homologous recombination deficiency status.

RESULTS

Targeted sequencing identified 5,018 germline variants, which were classified into 317 pathogenic, 3,611 variants of uncertain significance, and 1,090 benign variants. Seventy-one BTC cases (5.5%) had at least one pathogenic variant among 27 cancer-predisposing genes. Pathogenic germline variants enriched in BTCs were present in BRCA1, BRCA2, APC, and MSH6 (p <0.00185). PALB2 variants were marginally associated with BTC (p = 0.01). APC variants were predominantly found in ampulla of Vater carcinomas. Whole-genome sequencing demonstrated that three BTCs with pathogenic germline variants in BRCA2 and PALB2, accompanied by loss of heterozygosity, displayed homologous recombination deficiency. Conversely, pathogenic germline variants without a second hit or variants of other homologous recombination-related genes such as ATM and BRIP1 showed homologous recombination-proficient phenotypes.

CONCLUSIONS

In this study, we describe the heritability and actionability of variants in homologous recombination-related genes, which could be used to guide screening and therapeutic strategies for BTCs.

IMPACT AND IMPLICATIONS

We found that 5.5% of biliary tract cancers (BTCs) in a Japanese population possessed hereditary cancer-predisposing gene alterations, including in BRCA and genes associated with colorectal cancer. Two hits in homologous recombination-related genes were required to confer a homologous recombination-deficient phenotype. PARP inhibitors and DNA-damaging regimens may be effective strategies against BTCs exhibiting homologous recombination deficiency. Hence, in this study, genome-wide sequencing has revealed a potential new therapeutic strategy that could be applied to a subset of BTCs.

Strong Hereditary Predispositions to Colorectal Cancer

Cancer is one of the most common causes of death worldwide. A strong predisposition to cancer is generally only observed in colorectal cancer (5% of cases) and breast cancer (2% of cases). Colorectal cancer is the most common cancer with a strong genetic predisposition, but it includes dozens of various syndromes. This group includes familial adenomatous polyposis, attenuated familial adenomatous polyposis, MUTYH-associated polyposis, NTHL1-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis syndrome, Cowden syndrome, Lynch syndrome, and Muir-Torre syndrome. The common symptom of all these diseases is a very high risk of colorectal cancer, but depending on the condition, their course is different in terms of age and range of cancer occurrence. The rate of cancer development is determined by its conditioning genes, too. Hereditary predispositions to cancer of the intestine are a group of symptoms of heterogeneous diseases, and their proper diagnosis is crucial for the appropriate management of patients and their successful treatment. Mutations of specific genes cause strong colorectal cancer predispositions. Identifying mutations of predisposing genes will support proper diagnosis and application of appropriate screening programs to avoid malignant neoplasm.

Current clinical practice for familial adenomatous polyposis in Japan: A nationwide multicenter study

Introduction

In Japanese patients with familial adenomatous polyposis (FAP), colectomy tends to be postponed or avoided.

Aim

This study aimed to clarify the current clinical practice from a Japanese multicenter cohort study database.

Methods

We analyzed the records of 250 patients with non-dense FAP who did not require colorectal cancer removal. The clinical outcomes were compared between patients who received colectomy (n = 142) (Group A) and those who did not receive colectomy (n = 108) (Group B).

Results

The colectomy rate based on the age at the final follow-up examination was 46%, 60%, 54%, 65%, at ≤29, 30-39, 40-49, and ≥ 50 years, respectively (P = .11). The development of colorectal cancer did not differ between Groups A and B (25% vs 22% P = .67); however, colorectal cancer was diagnosed at the Tis stage in 88% of the patients with colorectal cancer in Group B, and 34% of the patients with colorectal cancer in Group A (P < .01). Regarding survival, all patients in Group B were alive at the final follow-up examination. In contrast, six patients in Group A died, including three patients with desmoid tumors and one with colon cancer.

Conclusion

Over one-third of patients with non-dense FAP (polyps ≤ 1000) in Japan did not receive colectomy at >30 years of age, and patients who managed without colectomy showed acceptable survival with the early diagnosis of colorectal cancer, and a very low incidence of desmoid tumor development, indicating that this approach represents a potential option for the management of selected non-dense FAP patients.

A Rare Case of Multiple Gastrointestinal Stromal Tumors Coexisting with a Rectal Adenocarcinoma in a Patient with Attenuated Familial Adenomatous Polyposis Syndrome and a Mini Review of the Literature

Background: Multiple gastrointestinal stromal tumors (GISTs) are extremely rare entities that exist either as spontaneous GISTs or as part of various syndromes, such as Carney’s triad and type I neurofibromatosis (NF1). Attenuated familial adenomatous polyposis (AFAP) is a variant of familial adenomatous polyposis (FAP) with a milder clinical presentation. Both GISTs and AFAP have been reported to coexist with colorectal cancer, but the coexistence of GISTs and AFAP has never been reported in the literature before. Case report: A 45-year-old male patient with known AFAP arrived scheduled for a total colectomy and ileo-rectal anastomosis due to the malignancy of one of the previously biopsied polyps of the upper rectum. Intraoperatively, multiple nodular tumors were found at the jejunum within a length of 45 cm, for which an enterectomy and enteroanastomosis were performed. A histopathological examination of the whole colectomy specimen confirmed the presence of multiple polyps in the large intestine along with a rectal invasive adenocarcinoma. At the same time, in the examined part of the small intestine, 15 GISTs sized from 0.5 to 2.0 cm of prognostic group I, were identified. The patient’s postoperative course was uncomplicated. Conclusion: Multiple GISTs may present as an asymptomatic disease, and the same thing is true for colorectal cancer. Therefore, the appropriate screening is crucial for entities such as AFAP, since the surgery was performed because of the malignant transformation in one of the polyps and revealed multiple GISTs, as well.

Role of endoscopy in patients with familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is a hereditary disease that, without intervention, will cause nearly all patients to develop colorectal cancer by the age of 45. However, even after prophylactic colorectal surgery the eventual development of duodenal adenomas leads to an additional risk of duodenal and ampullary cancers. Endoscopy is an essential part of the multidisciplinary management of FAP to aid the early identification or prevention of advanced gastrointestinal malignancy. This review article details the current evidence and consensus guidance available regarding the role of endoscopic surveillance and treatment strategies for FAP.

Identification of Germline Mutations in Genes Involved in Classic FAP in Patients from Northern Brazil

BACKGROUND

Colorectal cancer is a common cancer worldwide, with 5-10% of cases being hereditary. Familial adenomatous polyposis syndrome (FAP) is caused by germline mutations in the APC gene or rarely in the MUTYH gene.

PATIENTS AND METHODS

This work did not identify germline mutations in the MUTYH, NTHL1, POLD1 and POLE genes in 15 individuals belonging to five families with classic FAP, who had the mutation in the APC gene confirmed in a previous study. Our results support mutations in the APC gene as the main genetic contribution of classical FAP with severe phenotype. In the family that had the most aggressive form of the disease, we performed an array-based Comparative Genomic Hybridization analysis and identified the germinal loss of an allele of the NOTCH2 and BMPR2 genes in the mother (proband) and daughter. In order to validate the involvement of these genes in the other four families of this study, we analyzed the DNA copy number variation in the peripheral blood of the 15 participants.

RESULTS

FAP is a syndrome with considerable genetic and phenotypic heterogeneity and this phenomenon may explain the presence of secondary genetic alterations, such as the allelic loss of NOTCH2 and BMPR2 genes, found only in one family in this study. The CNV analysis confirmed that only the two members of the FAP2 family (patient 02H and 02F) had a deletion of these two genes, as the aCGH methodology had found. The other study participants did not show allelic loss for these two genes.

CONCLUSION

Validation in a larger number of families could confirm the presence of these new genetic alterations in classic FAP and improve understanding of the different types of aggressiveness of the disease.

Attenuated Familial Adenomatous Polyposis: A Phenotypic Diagnosis but Obsolete Term?

BACKGROUND

Attenuated familial adenomatous polyposis is characterised by low number (≤100) and delayed development of colorectal adenomas. Various definitions have been used, and genotype-phenotype correlations have been suggested.

OBJECTIVE

We aimed to evaluate phenotypic and genotypic correlation in patients with presumed attenuated familial adenomatous polyposis and assess familial variability.

DESIGN

This is a retrospective study.

SETTINGS

This study was conducted at a tertiary polyposis registry.

PATIENTS

Individuals with attenuated familial adenomatous polyposis were identified. Phenotypic group was defined as 100 or fewer adenomas at age 25 years and genotypic group was defined as a variant in the adenomatous polyposis coli region associated with attenuated familial adenomatous polyposis. Pathology polyp count was used for patients who had undergone surgery and endoscopic polyp count for those with intact colon.

MAIN OUTCOME MEASURES

We evaluated phenotypic and genotypic correlation in patients with presumed attenuated familial adenomatous polyposis and familial variability.

RESULTS

A total of 69 patients were identified in the phenotypic group, of whom 54 (78%) had a pathogenic variant in the attenuated regions of the adenomatous polyposis coli gene. Forty-eight (70%) had intact colon (median age at last colonoscopy 43 [25-73] years; median endoscopic polyp count 20 [0-100]) and 21 (30%) had undergone colectomy (median age at surgery 45 [25-54] years; median pathology polyp count 43 [3-100]). Eighty-three patients were identified in the genotypic group of which 54 (65%) had attenuated phenotype. Inter- and intrafamilial variability were observed.

LIMITATIONS

This study was limited by its retrospective nature and single-center experience.

CONCLUSION

Phenotype in familial adenomatous polyposis lies on a spectrum and is determined in part by genotype and age at adenoma count. Diagnosis of attenuated familial adenomatous polyposis should be based on phenotype; genotype is not a reliable indicator. Management should be personalized according to the phenotype of each individual. See Video Abstract at http://links.lww.com/DCR/B775.

POLIPOSIS ADENOMATOSA FAMILIAR ATENUADA UN DIAGNSTICO FENOTPICO PERO TRMINO OBSOLETO

ANTECEDENTES:La poliposis adenomatosa familiar atenuada se caracteriza por un número bajo (≤100) y desarrollo retardado de adenomas colorrectales. Se han utilizado varias definiciones y se han sugerido correlaciones genotipo-fenotipo.OBJETIVO:Nuestro objetivo es evaluar la correlación fenotípica y genotípica en pacientes con presunta poliposis adenomatosa familiar atenuada y evaluar la variabilidad familiar.DISEÑO:Este es un estudio retrospectivo.AJUSTE:Este estudio se realizó en un registro terciario de poliposis.PACIENTES:Se identificaron individuos con poliposis adenomatosa familiar atenuada. El grupo fenotípico se definió como ≤100 adenomas a la edad de 25 años y el grupo genotípico se definió como una variante en la región de poliposis coli adenomatosa asociada con poliposis adenomatosa familiar atenuada. Se utilizó el recuento de pólipos en patología para los pacientes que se habían sometido a cirugía y el recuento de pólipos endoscópico para los que tenían el colon intacto.PRINCIPALES MEDIDAS DE RESULTADO:Evaluamos la correlación fenotípica y genotípica en pacientes con presunta poliposis adenomatosa familiar atenuada y variabilidad familiar.RESULTADOS:Un total de 69 pacientes se identificaron en el grupo fenotípico de los cuales 54 (78%) tenían una variante patogénica en las regiones atenuadas del gen de la poliposis coli adenomatosa. Cuarenta y ocho (70%) tenían colon intacto (edad media en la última colonoscopia 43 [25-73] años; mediana del recuento de pólipos endoscópicos 20 [0-100]) y 21 (30%) se habían sometido a colectomía (edad edia en el momento de la cirugía 45 [25-54] años; mediana del recuento de pólipos patológicos 43 [3-100]). Se identificaron 83 pacientes en el grupo genotípico de los cuales 54 (65%) tenían fenotipo atenuado. Se observó variabilidad inter e intrafamiliar.LIMITACIONES:Este estudio estuvo limitado por su naturaleza retrospectiva y la experiencia de un solo centro.CONCLUSIÓNES:El fenotipo en la poliposis adenomatosa familiar se encuentra en un espectro, determinado en parte por el genotipo y la edad en el momento del recuento de adenomas. El diagnóstico de poliposis adenomatosa familiar atenuada debe basarse en el fenotipo; el genotipo no es un indicador confiable. El manejo debe personalizarse según el fenotipo de cada individuo. Consulte Video Resumen en http://links.lww.com/DCR/B775.

Reviewing the occurrence of large genomic rearrangements in patients with inherited cancer predisposing syndromes: importance of a comprehensive molecular diagnosis

INTRODUCTION

Hereditary cancer predisposition syndromes are caused by germline pathogenic or likely pathogenic variants in cancer predisposition genes (CPG). The majority of pathogenic variants in CPGs are point mutations, but large gene rearrangements (LGRs) are present in several CPGs. LGRs can be much more difficult to characterize and perhaps they may have been neglected in molecular diagnoses.

AREAS COVERED

We aimed to evaluate the frequencies of germline LGRs in studies conducted in different populations worldwide through a qualitative systematic review based on an online literature research in PubMed. Two reviewers independently extracted data from published studies between 2009 and 2020. In total, 126 studies from 37 countries and 5 continents were included in the analysis. The number of studies in different continents ranged from 3 to 48 and for several countries there was an absolute lack of information. Asia and Europe represented most of the studies, and LGR frequencies varied from 3.04 to 15.06% in different continents. MLPA was one of the methods of choice in most studies (93%).

EXPERT OPINION

The LGR frequencies found in this review reinforce the need for comprehensive molecular testing regardless of the population of origin and should be considered by genetic counseling providers.

Incidental Finding of Attenuated Familial Adenomatous Polyposis

Attenuated familial adenomatous polyposis (AFAP) or attenuated adenomatous polyposis coli (AAPC) is defined as the milder polyposis phenotype of classic familial adenomatous polyposis (FAP). FAP syndromes are caused by germline mutations in the adenomatous polyposis coli (APC) gene. AFAP is an inherited autosomal dominant with predominant mutations at the far proximal (5′) end of the APC gene. Unlike FAP, AFAP is characterized by the occurrence of fewer than 100 adenomas that are found mostly in the proximal part of the colon with a delayed progression to colorectal cancer (CRC). The lower risk of development of colorectal cancer and extra-intestinal neoplasms is likely attributable to under-diagnosis. However, 2-5% of all CRCs happen because of inherited syndromes which include both hereditary polyposis syndromes and hereditary nonpolyposis colorectal cancer syndrome (HNPCC) or otherwise known as Lynch syndrome (LS). Here, we present a case of a 64-year-old Polish-speaking female in whom an incidental finding of polyposis turned out to be a malignancy. Our patient had a positive family history of colon cancer. The delay in performing an annual colonoscopy with endoscopic polypectomy per AFAP surveillance guidelines was supposedly delayed due to lack of insurance and language barrier. There were no metastases and she was negative for the APC gene mutation. Pathology was significant for moderately differentiated adenocarcinoma with intact mismatch repair protein (MMRP) (expression of MLH1, PMS2, MSH2, and MSH6) genes immune-histochemical staining. The patient underwent a subtotal colectomy with ileostomy without any complications. This study aimed to emphasize that communication with the patient in their primary language is essential to gather all the data which can lead to an accurate diagnosis and to provide adequate care. Physicians are required to have a professional interpreter to acquire the appropriate medical history and be more vigilant in following up with the patient in order to provide comprehensive care.

Endoscopic management of duodenal adenomatosis in familial adenomatous polyposis-A case-based review

Adenomatous polyposis (AP) diseases, including familial adenomatous polyposis (FAP), attenuated FAP (AFAP), and MUTYH‐associated polyposis (MAP), are the second most common hereditary causes of colorectal cancer. A frequent extra‐colonic manifestation of AP disease is duodenal polyposis, which may lead to duodenal cancer in up to 18% of AP patients. Endoscopic surveillance is recommended at 0.5‐ to 5‐year intervals depending on the extent of polyp growth and histological progression. Although the Spigelman classification is traditionally used to determine surveillance intervals, it lacks information on the (peri‐)ampullary site, where 50% of duodenal carcinomas are located. Hence, information on the papilla has recently been added as a prognostic marker. Patients with duodenal adenoma(s) ≥10 mm and ampullary adenomas of any size are suggested to be referred to an expert center for endoscopic therapy, particularly endoscopic mucosal resection and endoscopic ampullectomy. Nonetheless, despite the logic of this approach, the long‐term efficacy of endoscopic therapy is still to be demonstrated.

Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines 2020 for the Clinical Practice of Hereditary Colorectal Cancer

Hereditary colorectal cancer (HCRC) accounts for < 5% of all colorectal cancer cases. Some of the unique characteristics commonly encountered in HCRC cases include early age of onset, synchronous/metachronous cancer occurrence, and multiple cancers in other organs. These characteristics necessitate different management approaches, including diagnosis, treatment or surveillance, from sporadic colorectal cancer management. There are two representative HCRC, named familial adenomatous polyposis and Lynch syndrome. Other than these two HCRC syndromes, related disorders have also been reported. Several guidelines for hereditary disorders have already been published worldwide. In Japan, the first guideline for HCRC was prepared by the Japanese Society for Cancer of the Colon and Rectum (JSCCR), published in 2012 and revised in 2016. This revised version of the guideline was immediately translated into English and published in 2017. Since then, several new findings and novel disease concepts related to HCRC have been discovered. The currently diagnosed HCRC rate in daily clinical practice is relatively low; however, this is predicted to increase in the era of cancer genomic medicine, with the advancement of cancer multi-gene panel testing or whole genome testing, among others. Under these circumstances, the JSCCR guidelines 2020 for HCRC were prepared by consensus among members of the JSCCR HCRC Guideline Committee, based on a careful review of the evidence retrieved from literature searches, and considering the medical health insurance system and actual clinical practice settings in Japan. Herein, we present the English version of the JSCCR guidelines 2020 for HCRC.

Familial adenomatous polyposis in dogs: hereditary gastrointestinal polyposis in Jack Russell Terriers with germline APC mutations

Many hereditary disorders in dogs have equivalents in humans and thus attract attention as natural animal models. Breed predisposition to certain diseases often provides promising clues to explore novel hereditary disorders in dogs. Recently, cases of gastrointestinal (GI) polyps in Jack Russell Terriers (JRTs) have increased in Japan. In 21 affected JRTs, polyps were found in either or both the stomach and colorectum, with a predilection for the gastric antrum and rectum. Multiple polyps were found in 13 of 21 examined dogs, including 5 dogs with both gastric and colorectal polyps. Some dogs were found to have GI polyps at an early age, with the youngest case being 2.3 years old. Histopathologically, 43 of 46 GI polyps (93.5%) were diagnosed as adenomas or adenocarcinomas. Immunohistochemical analysis revealed cytoplasmic and nuclear accumulation of β-catenin in the tumor cells. As in the case of human patients with familial adenomatous polyposis, all examined JRTs with GI polyps (n = 21) harbored the identical heterozygous germline APC mutations, represented by a 2-bp substitution (c.[462A>T; 463A>T]). The latter substitution was a non-sense mutation (p.K155X) resulting in a truncated APC protein, thus suggesting a strong association with this cancer-prone disorder. Somatic mutation and loss of the wild-type APC allele were detected in the GI tumors of JRTs, suggesting that biallelic APC inactivation was involved in tumor development. This study demonstrated that despite differences in the disease conditions between human and dog diseases, germline APC mutation confers a predisposition to GI neoplastic polyps in both dogs and humans.

Increased Th17-Related Cytokine Serum Levels in Patients With Multiple Polyps of Unexplained Origin

Most patients with multiple colonic polyps do not have a known genetic or hereditary origin. Our aim was to analyze the presence of inflammatory cytokines and levels of glucose, insulin, and C-reactive protein (CRP) in patients with multiple colonic polyps.

Use of sanger and next-generation sequencing to screen for mosaic and intronic APC variants in unexplained colorectal polyposis patients

In addition to classic germline APC gene variants, APC mosaicism and deep intronic germline APC variants have also been reported to be causes of adenomatous polyposis. In this study, we investigated 80 unexplained colorectal polyposis patients without germline pathogenic variants in known polyposis predisposing genes to detect mosaic and deep intronic APC variants. All patients developed more than 50 colorectal polyps, with adenomas being predominantly observed. To detect APC mosaicism, we performed next-generation sequencing (NGS) in leukocyte DNA. Furthermore, using Sanger sequencing, the cohort was screened for the following previously reported deep intronic pathogenic germline APC variants: c.1408 + 731C > T, p.(Gly471Serfs*55), c.1408 + 735A > T, p.(Gly471Serfs*55), c.1408 + 729A > G, p.(Gly471Serfs*55) and c.532-941G > A, p.(Phe178Argfs*22). We did not detect mosaic or intronic APC variants in the screened unexplained colorectal polyposis patients. The results of this study indicate that the deep intronic APC variants investigated in this study are not a cause of colorectal polyposis in this Dutch population. In addition, NGS did not detect any further mosaic variants in our cohort.

Genetic epidemiology of colorectal cancer and associated cancers

We review here data on familial risk in colorectal cancer (CRC) generated from the Swedish Family-Cancer Database, the largest resource of its kind in the world. Although the concordant familial risk for CRC (i.e. CRC risk in families of CRC patients) has been reasonably well established, the studies on discordant familial risks (i.e. CRC risk in families with any other cancers) are rare. Because different cancers could be caused by shared genetic susceptibility or shared environment, data of associations of discordant cancers may provide useful information for identifying common risk factors. In analyses between any of 33 discordant cancers relative risks (RRs) for discordant cancers were estimated in families with increasing numbers of probands with CRC; in the reverse analyses, RRs for CRC were estimated in families with increasing numbers of probands with discordant cancers. In separate analyses, hereditary non-polyposis colorectal cancer (HNPCC) families were excluded from the study, based on HNPCC related double primary cancers, to assess the residual familial RRs. We further reviewed familial risks of colon and rectal cancers separately in search for distinct discordant associations. The reviewed data suggested that colon cancer was associated with a higher familial risk for CRC compared to rectal cancer. The previous data had reported associations of CRC with melanoma, thyroid and eye cancers. Nervous system cancer was only associated with colon cancer, and lung cancer only associated with rectal cancer. The reviewed data on discordant association may provide guidance to gene identification and may help genetic counseling.

Solid-pseudopapillary neoplasm of the pancreas in a patient with familial adenomatous polyposis: a case report

Background

Familial adenomatous polyposis (FAP) is characterized by the presence of hundreds to thousands of colonic polyps, and extracolonic manifestations are likely to occur. Pancreatic tumors are rare extracolonic manifestations in patients with FAP, among which solid-pseudopapillary neoplasm (SPN) are extremely rare. We report here a patient with an SPN of the pancreas found during the follow-up of FAP.

Case presentation

A 20-year-old woman was diagnosed with FAP 3 years previously by colonoscopy which revealed less than 100 colonic polyps within the entire colon. She complained of left upper abdominal pain and a 10-cm solid and cystic pancreatic tumor was found by computed tomography scan. Solid and cystic components within the tumor were seen on abdominal magnetic resonance imaging. Simultaneous laparoscopic resection of the distal pancreas and subtotal colectomy was performed. Histopathological findings confirmed the pancreatic tumor as an SPN without malignancy. Abnormal staining of beta-catenin was observed by immunohistochemical study. Multiple polyps in the colorectum were not malignant. Molecular biological analysis from peripheral blood samples revealed a decrease in the copy number of the promoter 1A and 1B region of the APC gene, which resulted in decreased expression of the APC gene.

Conclusions

A rare association of SPN with FAP is reported. The genetic background with relation to beta-catenin abnormalities is interesting to consider tumor development. So far, there are few reports of SPN in a patient with FAP. Both lesions were treated simultaneously by laparoscopic resection.

Modifiable Factors and Colon Cancer Risk in Thai Population

To demonstrate the possible impact of modifiable factors on colon cancer development in Thai population, we conducted this case-control study from June 2016 until June 2017. The study was conducted in 11 Thai provincial hospitals. The hospitals in this study were selected by stratification by regions. Patients included 504 ones who were newly diagnosed with colon cancer within 1 month. In the control group, 997 health individuals were enrolled. Both case and control were adjusted by age. The results of this study showed that age and socioeconomic factors were associated with colon cancer risk. In addition, it was found that family history of colon cancer had very high association with colon cancer risk. Behavioral factors, including smoking, inadequate physical exercise, and salty food consumption were associated with colon cancer. We detected no association between obesity, alcohol consumption, and colon cancer. The results suggested that colon cancer might have higher association with genetic factors than behavioral factors among Thai patients. Based on the results of this study, stop smoking and promote adequate physical activity are suggested to reduce the incidence of colon cancrr among Thai patients.

Risk Factors and Genetic Predisposition in Colorectal Cancer: A Study on Young and Old Adults

According to GLOBOCAN 2018 data Colorectal cancer (CRC) represents the third most commonly diagnosed cancer in the world and has the second-highest mortality rate. The incidence of CRC has been rising worldwide, the majority of cases being in developing countries mostly due to the adoption of an unhealthy lifestyle. The main driving factors behind CRC are a sedentary lifestyle, obesity, red meat consumption, alcohol, and tobacco; however, early detection screenings and standardized treatment options have reduced CRC mortality. Better family history and genetic testing can help those with a hereditary predisposition in taking preventative measures.

Novel Pathogenic Germline Variant of the Adenomatous Polyposis Coli (APC) Gene, p.S2627Gfs*12 Identified in a Mild Phenotype of APC-Associated Polyposis: A Case Report

Patient: Male, 80-year-old

Final Diagnosis: Attenuated APC-associated polyposis

Symptoms: Colon polyps • renal carcinoma

Medication: —

Clinical Procedure: —

Specialty: Genetics

Candidate Gene Discovery in Hereditary Colorectal Cancer and Polyposis Syndromes-Considerations for Future Studies

To discover novel high-penetrant risk loci for hereditary colorectal cancer (hCRC) and polyposis syndromes many whole-exome and whole-genome sequencing (WES/WGS) studies have been performed. Remarkably, these studies resulted in only a few novel high-penetrant risk genes. Given this observation, the possibility and strategy to identify high-penetrant risk genes for hCRC and polyposis needs reconsideration. Therefore, we reviewed the study design of WES/WGS-based hCRC and polyposis gene discovery studies (n = 37) and provide recommendations to optimize discovery and validation strategies. The group of genetically unresolved patients is phenotypically heterogeneous, and likely composed of distinct molecular subtypes. This knowledge advocates for the screening of a homogeneous, stringently preselected discovery cohort and obtaining multi-level evidence for variant pathogenicity. This evidence can be collected by characterizing the molecular landscape of tumors from individuals with the same affected gene or by functional validation in cell-based models. Together, the combined approach of a phenotype-driven, tumor-based candidate gene search might elucidate the potential contribution of novel genetic predispositions in genetically unresolved hCRC and polyposis.

American Society for Gastrointestinal Endoscopy guideline on the role of endoscopy in familial adenomatous polyposis syndromes

Familial adenomatous polyposis (FAP) syndrome is a complex entity, which includes FAP, attenuated FAP, and MUTYH-associated polyposis. These patients are at significant risk for colorectal cancer and carry additional risks for extracolonic malignancies. In this guideline, we reviewed the most recent literature to formulate recommendations on the role of endoscopy in this patient population. Relevant clinical questions were how to identify high-risk individuals warranting genetic testing, when to start screening examinations, what are appropriate surveillance intervals, how to identify endoscopically high-risk features, and what is the role of chemoprevention. A systematic literature search from 2005 to 2018 was performed, in addition to the inclusion of seminal historical studies. Most studies were from worldwide registries, which have compiled years of data regarding the natural history and cancer risks in this cohort. Given that most studies were retrospective, recommendations were based on epidemiologic data and expert opinion. Management of colorectal polyps in FAP has not changed much in recent years, as colectomy in FAP is the standard of care. What is new, however, is the developing body of literature on the role of endoscopy in managing upper GI and small-bowel polyposis, as patients are living longer and improved endoscopic technologies have emerged.

A rare missense variant in APC interrupts splicing and causes AFAP in two Danish families

Background

We report the first case of a missense variant in the APC gene that interrupts splicing by creating a new cryptic acceptor site. The variant, c.289G>A, p.(Gly97Arg), is located in exon 3, and qualitative and semi-quantitative RNA splicing analysis reveal that the variant results in skipping of the last 70 nucleotides of the exon, which leads to the introduction of a frameshift and a premature stop codon.

Case presentation

The variant was detected in two, apparently unrelated, Danish families with an accumulation of colorectal cancers, colonic adenomas and other cancers. The families both have an attenuated familial adenomatous polyposis phenotype, which is consistent with the association of pathogenic variants in the 5′ end of the gene.

One variant-carrier also had Caroli Disease and a Caroli Disease associated hepatic mucinous cystadenocarcinoma. This is the first description of a person with both Caroli Disease and a pathogenic APC variant, and although the APC variant is not known to be connected to the development of the hepatic malformations in Caroli Disease, it remains unclear whether the variant could have contributed to the carcinogenesis of the liver tumour.

Conclusions

Based on functional and co-segregation data we classify the APC c.289G>A, p.(Gly97Arg) variant as pathogenic (class 5). Our findings emphasize the importance of a functional evaluation of missense variants although located far from the exon-intron boundaries.

Colon Cancer: A Clinician's Perspective in 2019

Colon cancer is a common preventable cancer. With the adoption of widespread colon cancer screening in the developed countries, the incidence and mortality of colon cancer have decreased in the targeted population. But unfortunately, the incidence and mortality of colorectal cancer (CRC) have been increasing over the last 25 years in the young adults below the age of 50. There is disparity in benefit, i.e. reduction in risk of death between right-sided and left-sided colon cancer by screening colonoscopy. The reason could be multifactorial and various measures have been taken to decrease this disparity. Although most of the screened populations are average risk individuals, a minority of the population have various risk factors for developing colon cancer and need to follow specific colon cancer screening guidelines. Gene mutations (adenomatous polyposis coli (APC), deleted in colon cancer (DCC), K-ras, p53, B-Raf proto-oncogene serine/threonine kinase (BRAF), mismatch repair genes) and microsatellite instability lead to the development of colon cancer. Although various non-invasive methods of colon cancer screening are now available, colonoscopy remains the gold standard of colon cancer screening and adenoma detection rate is now being used as the quality metrics in screening colonoscopy. Although Multi-Society Task Force (MSTF) and American College of Physicians (ACP) recommend initiating screening colonoscopy at age 50 years in all individuals except African Americans who should begin screening colonoscopy at age 45 years, the American Cancer Society (ACS) recommends initiating screening colonoscopy at age 45 years in all individuals irrespective of race and ethnicity. Low-volume split-dose prep has been found to be as effective as high-volume split-dose prep and more tolerable to patients with increased compliance. Boston bowel preparation scale is recommended to measure the quality of colon cleansing. CRC is curative if it is diagnosed at an early stage but various palliative treatment options (endoscopic, oncologic and surgical) are available in advanced stages of this cancer. Adequate number of lymph node assessment during surgery is essential in accurate staging of CRC. Checkpoint inhibitors have been found to have dramatic response and durable clinical benefit in dMMR/MSI-H metastatic CRC. Different genetic and immune-oncologic research trials are ongoing for early detection and better management of CRC.

Current status of the genetic susceptibility in attenuated adenomatous polyposis

Adenomatous polyposis (AP) is classified according to cumulative adenoma number in classical AP (CAP) and attenuated AP (AAP). Genetic susceptibility is the major risk factor in CAP due to mutations in the known high predisposition genes APC and MUTYH. However, the contribution of genetic susceptibility to AAP is lower and less understood. New predisposition genes have been recently proposed, and some of them have been validated, but their scarcity hinders accurate risk estimations and prevalence calculations. AAP is a heterogeneous condition in terms of severity, clinical features and heritability. Therefore, clinicians do not have strong discriminating criteria for the recommendation of the genetic study of known predisposition genes, and the detection rate is low. Elucidation and knowledge of new AAP high predisposition genes are of great importance to offer accurate genetic counseling to the patient and family members. This review aims to update the genetic knowledge of AAP, and to expound the difficulties involved in the genetic analysis of a highly heterogeneous condition such as AAP.

Acute changes in colonic PGE2 levels as a biomarker of efficacy after treatment of the Pirc (F344/NTac-Apc am1137) rat with celecoxib

OBJECTIVE

This study sought to evaluate short-term treatment with COX-2 inhibitors and acute changes in colonic PGE2 levels as predictors of long-term efficacy in a genetic model of colorectal cancer.

METHODS

Celecoxib oral suspension (40 mg/kg BID) was dosed to Apc-mutant Pirc (F344/NTac-Apcam1137) rats for 4 days (short-term group), or the equivalent dose of 1500 ppm celecoxib was administered in the diet for 4 months (long-term group). Percent inhibition of colonic PGE2 was calculated, and the reduction in colonic PGE2 was assessed in relation to suppression of adenomatous colon polyps.

RESULTS

Colonic mucosa PGE2 was fourfold higher in Pirc than in F344 wild-type rats (21 vs. 5.6 pg/mg epithelial tissue), due at least in part to higher COX-2 expression, and this was confirmed by elevated PGE2-d11 levels in Pirc colonic S9 incubations. In the 4-day study, dose-dependent reductions in PGE2 were observed in colonic epithelium (-33% (P>0.05) and -57% (P=0.0012)), after low- and high-dose celecoxib treatments of 4 mg/kg and 40 mg/kg (bid), respectively. In the 4-month study, 1500 ppm celecoxib suppressed colonic epithelium PGE2 by 43.5%, and tumor multiplicity by 80% (P<0.0015). Suppression of plasma 6-keto PGF1α also was corroborated following long-term treatment with 1500 ppm celecoxib (P<0.05).

CONCLUSIONS

Acute changes in colonic mucosa PGE2 provided a rapid means of predicting long-term chemopreventive effects from celecoxib, and might be useful for screening of new COX-2 inhibitor compounds.

Attenuated familial adenomatous polyposis (AFAP) in a patient associated with a novel mutation in APC

Familial adenomatous polyposis (FAP) is an autosomal dominant syndrome associated with mutation in the adenomatous polyposis coli (APC) gene, a tumour suppressor located on chromosome 5q21. Attenuated familial adenomatous polyposis (AFAP) is a variant associated with fewer and later onset of colon polyps. AFAP-associated APC mutations have largely been found before codon 157, in exon 9 or after codon 1595. We present the case of a 44-year-old man incidentally found to have numerous gastric polyps during bariatric surgery, with innumerable polyps in the remaining part of the stomach and the entire colon, with rectal sparing, consistent with AFAP phenotype. Genetic testing demonstrated the c.7682dup (p.Ser2562Lysfs*21) variant in exon 15 of APC. This represents a previously undescribed APC mutation. This mutation likely yields end-binding protein 1 and human disc large binding protein inactivation, causing cell cycle microtubule dysregulation and tumour suppressor inactivation. Through loss of these regulatory mechanisms, this mutation is associated with AFAP phenotype. The patient was treated surgically and is doing well.

Next-generation sequencing with comprehensive bioinformatics analysis facilitates somatic mosaic APC gene mutation detection in patients with familial adenomatous polyposis

Background

Familial adenomatous polyposis (FAP) is an autosomal dominant colorectal tumor characterized by numerous adenomatous colonic polyps that often lead to colon cancer. Although most patients with FAP harbored germline mutations in APC gene, it was recently recognized that patients with clinical FAP, but without detectable pathogenic mutations, could be associated with somatic mosaic APC mutation.

Methods

We reanalyzed the nest-generation sequencing (NGS) gene panel testing results of patients who were diagnosed with FAP, but did not have APC mutations, at Yonsei Cancer Prevention Center between July 2016 and March 2018. We tested several variant calling algorithms to identify low level mosaic variants. In one patient with a low frequency APC mutation, NGS analysis was performed together with endoscopic biopsy. Variant calling tools HaplotypeCaller, MuTect2, VarScan2, and Pindel were used. We also used 3′-Modified Oligonucleotides (MEMO)-PCR or conventional PCR for confirmation.

Results

Among 28 patients with clinical suspicion of FAP but no detectable pathogenic variants of colonic polyposis associated genes, somatic mosaic pathogenic variants were identified in seven patients. The variant allele frequency ranged from 0.3 to 7.7%. These variants were mostly detected through variant caller MuTect2 and Pindel, and were further confirmed using mutant enrichment with MEMO-PCR.

Conclusions

The NGS with an adequate combination of bioinformatics tools is effective to detect low level somatic variants in a single assay. Because mosaic APC mutations are more frequent than previously thought, the presence of mosaic mutations must be considered when analyzing genetic tests of patients with FAP.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0553-0) contains supplementary material, which is available to authorized users.

The interplay between intrinsic and extrinsic Wnt signaling in controlling intestinal transformation

The intestinal epithelial layer is the fastest renewing tissue in the human body. Due to its incredible turnover rate, the intestine is especially prone to develop cancer, in particular in the colon. Colorectal cancer (CRC) development is characterized by the stepwise accumulation of mutations over time, of which mutations in the tumor suppressor APC are often very early to occur. Generally, mutations in this gene lead to truncated APC proteins that cannot bind to β-catenin to promote its degradation, resulting in a constant overstimulation of the Wnt pathway. The level of intrinsic Wnt activation is dependent on the number of functional β-catenin binding sites remaining within the APC proteins, and the right amount of Wnt signaling is rate-limiting in the formation of polyps. In addition, the intestinal niche provides an extensive spectrum of Wnt ligands, amplifiers and antagonists that locally regulate basal Wnt levels and consequently influence polyp formation propensity. Here we will discuss the crosstalk between transforming epithelial cells and their regional niche in the development of intestinal cancer.

Hereditary Cancer Syndromes-A Primer on Diagnosis and Management, Part 2: Gastrointestinal Cancer Syndromes

Hereditary causes due to mutations and defects in certain genes account for roughly 5% to 10% of all colorectal cancers. These inherited syndromes have been associated with a 60% to 100% lifetime risk for development of colorectal cancer, depending on the genetic syndrome, and many also carry an increased risk for multiple extracolonic malignancies. In this second part of a review series on hereditary cancer syndromes, the focus will be to provide guidance on the features and management of the most commonly encountered hereditary colorectal cancers and polyposis conditions including Lynch syndrome, familial adenomatous polyposis, MUTYH-associated polyposis, and hamartomatous polyposis.

Molecular basis of familial adenomatous polyposis in the southeast of Brazil: identification of six novel mutations

BACKGROUND

The goal of this study was to screen point mutations and deletions in APC and MUTYH genes in patients suspected of familial adenomatous polyposis (FAP) in a Brazilian cohort.

METHODS

We used high-resolution melting, Sanger direct sequencing and multiplex ligation-dependent probe association (MLPA) assays to identify point mutations, and large genomic variations within the coding regions of APC and MUTYH genes.

RESULTS

We identified 19 causative mutations in 40 Brazilian patients from 20 different families. Four novel mutations were identified in the APC gene and two in the MUTYH gene. We also found a high intra- and inter-familial diversity regarding extracolonic manifestations, and gastric polyps were the most common manifestation found in our cohort.

CONCLUSION

We believe that the FAP mutational spectrum can be population-specific and screening FAP patients in different populations can improve pre-clinical diagnosis and improve clinical conduct.

APC mosaicism in a young woman with desmoid type fibromatosis and familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is usually caused by germline mutations in the adenomatous polyposis coli (APC) gene. The classic form is characterized by hundreds to thousands of adenomas in the colorectum and early onset colorectal cancer (CRC) if left untreated. FAP is also associated with multiple extra-colonic manifestations such as gastroduodenal polyps, osteomas, epidermoid cysts, fibromas and desmoids. Most desmoid tumours in FAP patients occur intra-abdominally. Approximately 15–20% of the APC mutations are de novo mutations. Somatic mosaicism has been reported in some sporadic cases of polyposis but is probably an underestimated cause of the disease. This case report presents the detection of a mosaic APC mutation in a 26-year-old woman who as a child had been diagnosed with desmoid type fibromatosis. FAP was suggested when she presented with extensive extra abdominal fibromatosis. Our findings indicate that APC mutations may be suspected in patients presenting with a desmoid regardless of its location. If there is clinical evidence that the patient has FAP, adenomas and colonic mucosa in addition to leukocyte DNA should be included in the screening, preferably using methods that are more sensitive than Sanger sequencing.

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.

A novel large germ line deletion in adenomatous polyposis coli (APC) gene associated with familial adenomatous polyposis

Background

Familial adenomatous polyposis (FAP) is a familial colorectal cancer predisposition syndrome characterized by the development of numerous colorectal polyps, which is inherited in an autosomal dominant manner. FAP is caused by germ line mutations in adenomatous polyposis coli (APC) gene. Here, we described the identification of a causative APC gene deletion associated with FAP in an Iranian family.

Methods

Diagnosis of FAP was based on clinical findings, family history, and medical records (colonoscopy and histopathological data) after the patients were referred to Reza Radiotherapy and Oncology Center, Iran, for colonoscopy. Blood samples were collected, and genomic DNA was extracted. APC mutation screening was conducted by target next‐generation sequencing and quantitative real‐time PCR.

Results

A novel heterozygous large deletion mutation, c.(135+1_136–1)_(*2113+1_*2114–1) spanning exon 3 to 16 [EX3_16 DEL] of APC gene (GenBank Accession# MG712911), was detected in a proband and all her affected relatives in five generations, which was absent in unaffected family members and normal controls.

Conclusions

This novel deletion is the first report, describing the largest deletion of APC gene. Our novel finding contributes to a more comprehensive database of germ line mutations of APC gene that could be used in medical practice for the molecular diagnosis, risk assessment susceptibility of the disease for the FAP patients.

An intestinal stem cell niche in Apc mutated neoplasia targetable by CtBP inhibition

C-terminal binding protein 2 (CtBP2) drives intestinal polyposis in the Apc^min mouse model of human Familial Adenomatous Polyposis. As CtBP2 is targetable by an inhibitor of its dehydrogenase domain, understanding CtBP2’s role in adenoma formation is necessary to optimize CtBP-targeted therapies in Apc mutated human neoplasia. Tumor initiating cell (TIC) populations were substantially decreased in Apc^minCtbp2^+/- intestinal epithelia. Moreover, normally nuclear Ctbp2 was mislocalized to the cytoplasm of intestinal crypt stem cells in Ctbp2^+/- mice, both Apc^min and wildtype, correlating with low/absent CD133 expression in those cells, and possibly explaining the lower burden of polyps in Apc^min Ctbp2^+/- mice. The CtBP inhibitor 4-chloro-hydroxyimino phenylpyruvate (4-Cl-HIPP) also robustly downregulated TIC populations and significantly decreased intestinal polyposis in Apc^min mice. We have therefore demonstrated a critical link between polyposis, intestinal TIC’s and Ctbp2 gene dosage or activity, supporting continued efforts targeting CtBP in the treatment or prevention of Apc mutated neoplasia.

Japanese Society for Cancer of the Colon and Rectum (JSCCR) Guidelines 2016 for the Clinical Practice of Hereditary Colorectal Cancer (Translated Version)

Hereditary colorectal cancer accounts for less than 5% of all colorectal cancer cases. Some of the unique characteristics that are commonly encountered in cases of hereditary colorectal cancer include early age at onset, synchronous/metachronous occurrence of the cancer, and association with multiple cancers in other organs, necessitating different management from sporadic colorectal cancer. While the diagnosis of familial adenomatous polyposis might be easy because usually 100 or more adenomas that develop in the colonic mucosa are in this condition, Lynch syndrome, which is the most commonly associated disease with hereditary colorectal cancer, is often missed in daily medical practice because of its relatively poorly defined clinical characteristics. In addition, the disease concept and diagnostic criteria for Lynch syndrome, which was once called hereditary non-polyposis colorectal cancer, have changed over time with continual research, thereby possibly creating confusion in clinical practice. Under these circumstances, the JSCCR Guideline Committee has developed the "JSCCR Guidelines 2016 for the Clinical Practice of Hereditary Colorectal Cancer (HCRC)," to allow delivery of appropriate medical care in daily practice to patients with familial adenomatous polyposis, Lynch syndrome, or other related diseases. The JSCCR Guidelines 2016 for HCRC were prepared by consensus reached among members of the JSCCR Guideline Committee, based on a careful review of the evidence retrieved from literature searches, and considering the medical health insurance system and actual clinical practice settings in Japan. Herein, we present the English version of the JSCCR Guidelines 2016 for HCRC.

Cancer Screening Recommendations and Clinical Management of Inherited Gastrointestinal Cancer Syndromes in Childhood

Hereditary gastrointestinal cancer predisposition syndromes have been well characterized, but management strategies and surveillance remain a major challenge, especially in childhood. In October 2016, the American Association for Cancer Research organized the AACR Childhood Cancer Predisposition Workshop in which international experts in care of children with a hereditary risk of cancer met to define surveillance strategies and management of children with cancer predisposition syndromes. In this article, we review the current literature in polyposis syndromes that can be diagnosed in childhood and may be associated with an increased incidence of gastrointestinal neoplasms and other cancer types. These disorders include adenomatous polyposis syndromes (APC and MUTYH), juvenile polyposis coli (BMPR1A and SMAD4), Peutz-Jeghers Syndrome (STK11/LKB1), and PTEN hamartoma tumor syndrome (PHTS; PTEN), which can present with a more limited juvenile polyposis phenotype. Herein, the panel of experts provides recommendations for clinical diagnosis, approach to genetic testing, and focus on cancer surveillance recommendations when appropriate during the pediatric period. We also review current controversies on genetic evaluation of patients with hepatoblastoma and indications for surveillance for this tumor. Childhood cancer risks and surveillance associated with disorders involving the mismatch repair genes, including Lynch syndrome and constitutional mismatch repair deficiency (CMMRD), are discussed elsewhere in this series. Clin Cancer Res; 23(13); e107-e14. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Update on Hereditary Colorectal Cancer: Improving the Clinical Utility of Multigene Panel Testing

Colorectal cancer (CRC), one of the most common cancers, is a major public health issue globally, especially in Westernized countries. Up to 35% of CRCs are thought to be due to heritable factors, but currently only 5% to 10% of CRCs are attributable to high-risk mutations in known CRC susceptibility genes, predominantly the mismatch repair genes (Lynch syndrome) and adenomatous polyposis coli gene (APC; familial adenomatous polyposis). In this era of precision medicine, high-risk mutation carriers, when identified, can be offered various risk management options that prevent cancers and improve survival, including risk-reducing medication, screening for early detection, and surgery. The practice of clinical genetics is currently transitioning from phenotype-directed single gene testing to multigene panels, now offered by numerous providers. For CRC, the genes included across these panels vary, ranging from well established, clinically actionable susceptibility genes with quantified magnitude of risk, to genes that lack extensive validation or have less evidence of association with CRC and, therefore, have minimal clinical utility. The current lack of consensus regarding inclusion of genes in CRC panels presents challenges in patient counseling and management, particularly when a variant in a less validated gene is identified. Furthermore, there remain considerable challenges regarding variant interpretation even for the well established CRC susceptibility genes. Ironically though, only through more widespread testing and the accumulation of large international data sets will sufficient information be generated to (i) enable well powered studies to determine if a gene is associated with CRC susceptibility, (ii) to develop better models for variant interpretation and (iii) to facilitate clinical translation.

Screening of colorectal cancer: present and future

INTRODUCTION

Colorectal cancer (CRC) is the third most common cancer in males and second in females, and the fourth most common cause of cancer death worldwide. Currently, about 60-70% of diagnosed cases in symptomatic patients are detected at an advanced stage of disease. Earlier stage detection through the use of screening strategies would allow for better outcomes in terms of reducing the disease burden. Areas covered: The aim of this paper is to review the current published evidence from literature which assesses the performance and effectiveness of different screening tests for the early detection of CRC. Expert commentary: Adequate screening strategies can reduce CRC incidence and mortality. In the last few decades, several tests have been proposed for CRC screening. To date, there is still insufficient evidence to identify which approach is definitively superior, and no screening strategy for CRC can therefore be defined as universally ideal. The best strategy would be the one that can be economically viable and to which the patient can adhere best to over time. The latest guidelines suggest colonoscopy every 10 years or annual fecal immuno-chemical test (FIT) for people with normal risk, while for individuals with high risk or hereditary syndromes specific recommendations are provided.

Hereditary Colorectal Polyposis and Cancer Syndromes: A Primer on Diagnosis and Management

Colorectal cancer (CRC) is the fourth most common cancer amongst men and women. Between 3 and 6% of all CRCs are attributed to well-defined inherited syndromes, including Lynch syndrome, familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), and several hamartomatous polyposis conditions. 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 narrative review examines the hereditary colorectal cancer and polyposis syndromes, their genetic basis, clinical management, and evidence supporting cancer screening.

Improving Mutation Screening in Patients with Colorectal Cancer Predisposition Using Next-Generation Sequencing

Identification of genetic alterations is important for family risk assessment in colorectal cancers. Next-generation sequencing (NGS) technologies provide useful tools for single-nucleotide and copy number variation (CNV) identification in many genes and samples simultaneously. Herein, we present the validation of current Multiplicom MASTR designs of mismatch repair combined to familial adenomatous polyposis genes in a single PCR reamplification test for eight DNA samples simultaneously on a MiSeq apparatus. Blood samples obtained from 224 patients were analyzed. We correctly identified the 97 mutations selected among 48 samples tested in a validation cohort. PMS2 NGS analysis of the eight positive controls identified single-nucleotide variations not detected with targeted referent methods. As NGS method could not discriminate if some of them were assigned to PMS2 or pseudogenes, only CNV analysis with multiplex ligand probe-dependent amplification confirmation was retained for clinical use. Twenty-seven new variants of unknown significance, 21 disease-causing variants, and two CNVs were detected among the 176 patient samples analyzed in diagnosis routine. MUTYH disease-causing mutations were identified in two patient samples assessed for mismatch repair testing, confirming that this method facilitates accurate and rapid individual risk assessments. In one sample, the MUTYH mutation was associated with a MSH6 disease-causing mutation, suggesting that this method is helpful to identify additional cancer risk modifiers and provides a useful tool to optimize clinical issues.

The genetic basis of colonic adenomatous polyposis syndromes

Colorectal cancer (CRC) is one of the most common forms of cancer worldwide and familial adenomatous polyposis (FAP) accounts for approximately 1% of all CRCs. Adenomatous polyposis syndromes can be divided into; familial adenomatous polyposis (FAP) – classic FAP and attenuated familial adenomatous polyposis (AFAP), MUTYH-associated polyposis (MAP), NTHL1-associated polyposis (NAP) and polymerase proofreading-associated polyposis (PPAP). The polyposis syndromes genetics and clinical manifestation of disease varies and cases with clinical diagnosis of FAP might molecularly show a different diagnosis.

This review examines different aspects of the adenomatous polyposis syndromes genetics and clinical manifestation of disease; in addition the genotype-phenotype and modifier alleles of FAP will be discussed. New technology has made it possible to diagnose some of the APC mutation negative patients into their respective syndromes. There still remain many molecularly undiagnosed adenomatous polyposis patients indicating that there remain causative genes to be discovered and with today’s technology these are expected to be identified in the near future. The knowledge about the role of modifier alleles in FAP will contribute to improved pre-symptomatic diagnosis and treatment.

New novel mutations will continually be discovered in genes already associated with disease and new genes will be discovered that are associated with adenomatous polyposis. The search for modifier alleles in FAP should be made a priority.

New frontiers in the treatment of colorectal cancer: Autophagy and the unfolded protein response as promising targets

Colorectal cancer (CRC), despite numerous therapeutic and screening attempts, still remains a major life-threatening malignancy. CRC etiology entails both genetic and environmental factors. Macroautophagy/autophagy and the unfolded protein response (UPR) are fundamental mechanisms involved in the regulation of cellular responses to environmental and genetic stresses. Both pathways are interconnected and regulate cellular responses to apoptotic stimuli. In this review, we address the epidemiology and risk factors of CRC, including genetic mutations leading to the occurrence of the disease. Next, we discuss mutations of genes related to autophagy and the UPR in CRC. Then, we discuss how autophagy and the UPR are involved in the regulation of CRC and how they associate with obesity and inflammatory responses in CRC. Finally, we provide perspectives for the modulation of autophagy and the UPR as new therapeutic options for CRC treatment.

Colonic Polyps: Diagnosis and Surveillance

Colorectal cancer begins as a polyp that is a benign growth on the mucosal surface of the colon or rectum. Over a period of 5 to 15 years, polyps can degenerate into a cancer, thus invading the colonic wall. Colorectal screening methods are designed to diagnose and remove polyps before they acquire invasive potential and develop into cancer. Screening for colorectal cancer can prevent and reduce mortality. Given the benefits and effectiveness of screening, guidelines exist from multiple organizations. These guidelines risk-stratify patients to determine the age of screening initiation and the interval for repeat screening. Categories of colorectal cancer risk include average risk, increased risk, and high risk based on individual and family medical history. Screening methods vary widely in the ability to diagnose and treat polyps and in the degree of invasiveness or risk of complication to the patient. Colonoscopy is held as the "gold standard" by which all other methods are compared; however, less-invasive modalities including computed tomographic colonography are increasing in popularity.