Phenotype and cancer risk of various polyposis syndromes

The Incidence Characteristics of Second Primary Malignancy after Diagnosis of Primary Colon and Rectal Cancer: A Population Based Study

Background

With the expanding population of colorectal cancer (CRC) survivors in the United States, one concerning issue is the risk of developing second primary malignancies (SPMs) for these CRC survivors. The present study attempts to identify the incidence characteristics of SPMs after diagnosis of first primary colon cancer (CC) and rectal cancer (RC).

Methods

189,890 CC and 83,802 RC cases were identified from Surveillance, Epidemiology and End Results Program (SEER) database. We performed rate analysis on incidence trend of SPMs in both CC and RC. Expected incidence rates were stratified by age, race and stage, calendar year of first CRC diagnosis and latency period since first CRC diagnosis. The standardized incidence ratios (SIRs), measure for estimating risk of SPMs, were calculated for CC and RC respectively.

Results

The trends of incidence of SPMs in both CC and RC were decreasing from 1992 to 2012. Both CC and RC survivors had higher risk of developing SPMs (SIRCC = 1.13; SIRRC = 1.05). For CC patients, the highest risks of SPM were cancers of small intestine (SIR = 4.03), colon (SIR = 1.87) and rectum (SIR = 1.80). For RC patients, the highest risks of SPMs were cancers of rectum (SIR = 2.88), small intestine (SIR = 2.16) and thyroid (SIR = 1.46). According to stratified analyses, we also identified incidence characteristics which were contributed to higher risk of developing SPMs, including the age between 20 and 40, American Indian/Alaska Native, localized stage, diagnosed at calendar year from 2002 to 2012 and the latency between 12 and 59 months.

Conclusions

Both CC and RC survivors remain at higher risk of developing SPMs. The identification of incidence characteristics of SPMs is extremely essential for continuous cancer surveillance among CRC survivors.

Autophagy and hypoxia in colonic adenomas related to aggressive features

AIM

The study investigated whether autophagic activity and hypoxia parallel the adenoma-carcinoma sequence.

METHOD

The study comprised 120 tubular adenomas with high-grade dysplasia, including 22 with questionable evidence of invasion, 37 with definite stromal invasion and 29 with severely dysplastic adenoma, 10 traditional serrated adenomas and 22 classical tubular adenomas lacking aggressive features. The samples were stained immunohistochemically for autophagy (LC3A and Beclin-1) and hypoxia-inducible factor1-alpha (HIF1α) markers.

RESULTS

LC3A was detected as diffuse cytoplasmic staining and as dense "stone-like" structures (SLS) within cytoplasmic vacuoles. Beclin-1 reactivity was purely cytoplasmic, whereas that of HIF1α was both cytoplasmic and nuclear. SLS counts in noninvasive, nontransformed areas of tubular adenomas were consistently low (median SLS = 0.5; 200× magnification), whereas a progressive increase was noted from areas of equivocal invasion (median SLS = 1.3; 200× magnification) and intramucosal carcinoma (median SLS = 1.4; 200× magnification) to unequivocal invasive foci (median SLS = 2.1; 200× magnification) (P < 0.0001). A similar association was shown for Beclin-1 and HIF1α expression (P < 0.05). Traditional serrated adenomas yielded low SLS counts and weak HIF1α reactivity, but high cytoplasmic LC3A and Beclin-1 expression (P < 0.01).

CONCLUSION

A hypoxia-driven autophagy in adenomatous polyps, when particularly intense and localized, is commonly associated with early invasion or severely dysplastic adenoma.

A Novel Germline Mutation in Exon 15 of the APC Gene in Attenuated Familial Adenomatous Polyposis: A Report of Two Cases

Attenuated familial adenomatous polyposis (AFAP) is a variant of familial adenomatous polyposis with fewer than one hundred colorectal polyps and a later age of onset of the cancer. Here, we report two cases of AFAP within family members. Each patient demonstrated the same novel germ line mutation in exon 15 of the adenomatous polyposis coli (APC) gene and was successfully managed with sulindac after refusal to perform colectomy: a 23-year-old man with incidentally diagnosed gastric adenoma and fundic gland polyps underwent colonoscopy, and fewer than 100 colorectal polyps were found; a 48-year-old woman who happened to be the mother of the 23-year-old man also showed fewer than 100 colorectal polyps on colonoscopy. Genetic analysis revealed a novel frameshift mutation in exon 15 of the APC gene. The deletion of adenine-guanine with the insertion of thymine in c.3833-3834 resulted in the formation of stop codon 1,287 in both patients. The patients were treated with sulindac due to their refusal to undergo colectomy. The annual follow-up upper endoscopy and colonoscopy in the following 2 years revealed significant regression of the colorectal polyps in both patients.

[Colorectal polyposis syndrome: a guide to diagnosis]

Biopsies and resection specimens of the gastrointestinal tract are a major part of the routine workload in many histopathology departments, whereby polypoid lesions are generally the main focus. In addition to distinguishing non-neoplastic from neoplastic polyps and evaluating the grade of dysplasia of the latter, the pathologist should always consider the possibility of an underlying polyposis syndrome. Not only have additional hereditary polyposis syndromes been identified in recent years due to a better understanding of their genetic and epigenetic alterations but also knowledge on well known polyposes has improved, leading to subtyping of various forms according to their different genotype. It is essential for the histopathologist to understand that the conventional histomorphology of individual polyps combined with information on the number and distribution of these lesions and clinical data can provide clues regarding a possible hereditary background. Therefore, the correct histological assessment of polyps is not just about getting the diagnosis right, it might also lead to genetic screening of family members and spouses.

Lower gastrointestinal tract cancer predisposition syndromes

Although inherited predisposition to colorectal cancer (CRC) has been suspected for more than 100 years, definitive proof of Mendelian syndromes had to await maturation of molecular genetic technologies. Since the l980s, the genetics of several clinically distinct entities has been revealed. Five disorders that share a hereditary predisposition to CRC are reviewed in this article.

Diagnostic yield of repeat capsule endoscopy and the effect on subsequent patient management

BACKGROUND

Capsule endoscopy (CE) has been shown to produce a high diagnostic yield in patients with obscure gastrointestinal bleeding (OGIB); however, in those with negative studies, management is controversial. Very few studies have reported on repeat CE in the same patient; data regarding this diagnostic strategy are limited.

OBJECTIVE

To determine the diagnostic yield of repeated CE studies and how this yield affects subsequent patient management.

METHODS

A retrospective chart review of all patients who underwent CE at St Paul's Hospital (Vancouver, British Columbia) between December 2001 and June 2009 was conducted. Patients who underwent subsequent repeat CE were identified and divided into one of four subgroups. Findings were classified as positive or negative.

RESULTS

Eighty-two of 676 patients underwent more than one CE study. Group 1 (incomplete study) included 22 patients (27%) and yielded 10 positive findings (45%). Group 2 (screening) comprised four patients (5%) and yielded two positive findings (50%). Group 3 (ongoing symptoms despite previous negative study) totalled 26 patients (32%) and yielded 10 positive findings (38%). Group 4 (previous positive study with treatment/investigation) included 30 patients (37%) and yielded 23 positive findings (77%). Overall, the present study found positive findings in 55% (45 of 82) of repeated CE cases, which resulted in a change in management in 39% (n=32) of the patients.

CONCLUSION

Due to the high diagnostic yield and noninvasive nature of CE, repeat CE appears to be of benefit and should be considered for specific patients before other types of small bowel studies.

Three novel mutations of the APC gene in Korean patients with familial adenomatous polyposis

Germline mutations within the adenomatous polyposis coli (APC) gene are associated with familial adenomatous polyposis (FAP), an autosomal dominant disease predisposing individuals to colorectal cancer. Identification of APC mutations has important implications for genetic counseling and management of FAP patients. We examined the APC mutation status of 10 Korean FAP patients by polymerase chain reaction-direct sequencing method and found six APC mutations, including three novel mutations. Testing for MUTYH mutation was done for FAP patients in whom no mutation in the APC gene was identified. Three novel mutations (c.1654_1663delTCTTGGCGAG, c.3709C>T, and c.6092_6094delinsTT) and three previously reported mutations (c.3631_3632delAT, c.4438C>T, and c.4612_4613delGA) were detected. The MUTYH mutation was not detected in any of the four FAP patients without an APC mutation. This finding of three novel mutations in a group of Korean FAP patients broadens the spectrum of APC mutations.

Matrix metalloproteinases in the urine and tissue of patients with juvenile polyps: potential biomarkers for the presence of polyps

BACKGROUND AND AIMS

Juvenile polyps are the most common type of pediatric gastrointestinal polyp and are typically characterized as hamartomatous overgrowths. Juvenile polyps are highly vascularized tissues and display a markedly increased mucosal microcirculation. Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes that play an essential role in the physiological degradation of the extracellular matrix in normal development, tumor invasion, and metastasis, as well as angiogenesis. We hypothesized that the presence of these enzymes in urine may serve as clinical biomarkers of juvenile polyps.

PATIENTS AND METHODS

In this preliminary study, we analyzed 32 urine samples collected prospectively from 16 subjects with known or suspected juvenile polyps who presented to the endoscopy unit for colonoscopic evaluation and 16 age- and sex-matched controls. Urinary MMPs were analyzed by zymography and their localized tissue expression was assayed via immunohistochemistry of tissue sections.

RESULTS

MMPs were detected in the urine of patients with juvenile polyps with significantly higher frequency when compared with urine of control subjects. In addition, immunohistochemistry demonstrated that high levels of MMPs were localized in the epithelium and lamina propria of polyp tissue when compared with colonic tissue collected from healthy control subjects.

CONCLUSIONS

These data are the first to demonstrate that MMPs are present in the urine and tissue of patients with juvenile polyps, and these enzymes have the potential to serve as surrogate markers for the presence of polyps.

Enteroscopy

Until the end of the 20th century, push enteroscopy (PE) was the most commonly used method for the endoscopic investigation of the small bowel. However, PE has been almost completely replaced by double balloon enteroscopy (DBE). Undoubtedly the major endoscopic breakthrough of the last decade, DBE has contributed to the better diagnosis and understanding of diseases of the small bowel, opening-up this obscure part of the gastrointestinal tract to visualisation. Modern diagnostic and therapeutic DBE allows for a deeper and more thorough evaluation of the small bowel than PE, enabling the detection of more pathological lesions. In addition, DBE has for the first time enabled endoscopists to observe the entire small intestine, and has provided endoscopic interventions such as cauterisation of bleeding lesions, polypectomy, placement of small bowel stents, and foreign-body extraction.

[Screening and surveillance for hereditary polyposis and non-polyposis syndromes with capsule endoscopy]

The hereditary polyposis syndromes and non-polyposis colorectal carcinoma have been considered as scarcely occurring but inheritable dominant autosomal syndromes. The increasing risk of small bowel carcinoma and prevention of obstruction and intussusception have been making frequent and acute surgical interventions unavoidably led to the necessity of screening and surveillance the patients. Earlier the diagnosis of these symptoms was difficult to establish because traditional radiological methods have a low yield for small polyps. Furthermore, small bowel is only partially accessible with traditional endoscopic techniques such as upper endoscopy, colonoscopy and push-enteroscopy. The "wireless" capsule endoscopy has opened the way then for the non-invasive and painless test of the entire small intestine. - Test results have been cumulated to justify the efficiency and safety of capsule endoscopy concerning the syndromes above. This method can be applied safely even consequently to repeatedly performed surgical interventions by low risk of capsule retention. As the results compared of the diagnosed familial adenomatous polyposis and of Peutz-Jeghers syndrome reflect on capsule endoscopy, its diagnostic sensitiveness is stated as significantly higher than the Barium-contrast X-Ray and MR-enterography. Nevertheless, determination of size and location of polyps has become more problematic when evaluating the test results.

Surveillance and management of upper gastrointestinal disease in Familial Adenomatous Polyposis

Almost all patients affected by Familial Adenomatous polyposis (FAP) will develop foregut as well as hindgut polyps, and following prophylactic colectomy duodenal cancer constitutes one of the leading causes of death in screened populations. Without prophylactic colectomy, FAP patients predictably develop colorectal cancer, but the lifetime risk of upper gastrointestinal cancer is lower, estimated at approximately 5%. Management of the upper gastrointestinal cancer risk is one of the greatest challenges facing clinicians involved in the care of Polyposis families, and with improved survival following prophylactic colectomy, the burden of foregut disease (particularly duodenal adenomatosis) will increase. Until recently, the value of upper gastrointestinal surveillance in FAP populations has been contentious, but with improved understanding of the natural history coupled with developments in surgery, interventional endoscopy and medical therapy, treatment algorithms for duodenal adenomatosis in FAP are becoming clearer.

Familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is an autosomal-dominant colorectal cancer syndrome, caused by a germline mutation in the adenomatous polyposis coli (APC) gene, on chromosome 5q21. It is characterized by hundreds of adenomatous colorectal polyps, with an almost inevitable progression to colorectal cancer at an average age of 35 to 40 yr. Associated features include upper gastrointestinal tract polyps, congenital hypertrophy of the retinal pigment epithelium, desmoid tumors, and other extracolonic malignancies. Gardner syndrome is more of a historical subdivision of FAP, characterized by osteomas, dental anomalies, epidermal cysts, and soft tissue tumors. Other specified variants include Turcot syndrome (associated with central nervous system malignancies) and hereditary desmoid disease. Several genotype-phenotype correlations have been observed. Attenuated FAP is a phenotypically distinct entity, presenting with fewer than 100 adenomas. Multiple colorectal adenomas can also be caused by mutations in the human MutY homologue (MYH) gene, in an autosomal recessive condition referred to as MYH associated polyposis (MAP). Endoscopic screening of FAP probands and relatives is advocated as early as the ages of 10-12 yr, with the objective of reducing the occurrence of colorectal cancer. Colectomy remains the optimal prophylactic treatment, while the choice of procedure (subtotal vs proctocolectomy) is still controversial. Along with identifying better chemopreventive agents, optimizing screening of extracolonic cancers and applying new radiological and endoscopic technology to the diagnosis and management of extracolonic features are the major challenges for the future.

Endoscopic management of familial colonic neoplasia

Heredity plays an important causative role in a large percentage of colorectal cancers. Clinical recognition of the hereditary polyposis syndromes, hereditary nonpolyposis colorectal cancer, and common familial colorectal cancer is essential because screening, surveillance, and treatment among affected individuals and their family members differs from that recommended for the general population. More intensive cancer screening and surveillance is required if premature death is to be avoided. Genetic testing is commercially available for most of the hereditary colorectal cancer syndromes and can greatly facilitate the management of patients if properly undertaken.

De novo crypt formation and juvenile polyposis on BMP inhibition in mouse intestine

Little is known about the signaling mechanisms that determine the highly regular patterning of the intestinal epithelium into crypts and villi. With the use of mouse models, we show that bone morphogenetic protein (BMP)-4 expression occurs exclusively in the intravillus mesenchyme. Villus epithelial cells respond to the BMP signal. Inhibition of BMP signaling by transgenic expression of noggin results in the formation of numerous ectopic crypt units perpendicular to the crypt-villus axis. These changes phenocopy the intestinal histopathology of patients with the cancer predisposition syndrome juvenile polyposis (JP), including the frequent occurrence of intraepithelial neoplasia. Many JP cases are known to harbor mutations in BMP pathway genes. These data indicate that intestinal BMP signaling represses de novo crypt formation and polyp growth.

Gastrointestinal polyps and polyposis syndromes in children

Gastrointestinal polyps are common during childhood and most often present with painless rectal bleeding. Most polyps occur as isolated colonic lesions and are not harbingers of an underlying genetic disorder, nor do they bestow a risk of gastrointestinal cancer. The astute pediatrician must be aware, however, that occasionally polyps may occur in the context of a genetic polyposis disorder characterized by an increase in the life-time risk of cancer in the gastrointestinal tract and other organ systems. This review outlines the major polyposis syndromes affecting children and highlights associated findings that might clue the alert physician to an underlying diagnosis. Recent developments in the understanding of the genetics of each disorder are emphasized.

The genetics of pancreatic adenocarcinoma: a roadmap for a mouse model

Pancreatic cancer is among the leading causes of cancer death. Although a genetic profile for pancreatic cancer is emerging, many biological aspects of this disease are poorly understood. Indeed, fundamental questions regarding progenitor cell lineages, host stromal milieu, and the role of specific genetic alterations in tumor progression remain unresolved. A mouse model engineered with signature mutations would provide a powerful ally in the study of pancreatic cancer biology and may guide improved prognostic assessment and treatment for the human disease. In this review, we discuss the molecular basis for normal pancreatic development and the genetics of human pancreatic adenocarcinoma in the hope of charting a course for the development of a faithful mouse model for this lethal cancer.

Pathology of colorectal cancer

The earliest phases of colorectal tumourigenesis initiate in the normal mucosa, with a generalised disorder of cell replication, and with the appearance of clusters of enlarged crypts (aberrant crypts) showing proliferative, biochemical and biomolecular abnormalities. The large majority of colorectal malignancies develop from adenomatous polyps. These can be defined as well demarcated masses of epithelial dysplasia, with uncontrolled crypt cell division. An adenoma can be considered malignant when neoplastic cells pass through the muscularis mucosae and infiltrate the submucosa. Definitions like "carcinoma in situ" or "intramucosal carcinoma" should be abandoned, since they lead to confusion. Although several lines of evidence indicate that carcinomas usually originate from pre-existing adenomas, this does not imply that all polyps undergo malignant changes, and does not exclude "de novo" carcinogenesis. Besides adenomas, other types of polypoid lesions include hyperplastic polyps (showing elongated crypts often with cystic dilatation), serrated adenomas (with a serrated glandular pattern], flat adenomas (flat lesions which are difficult to detect in routine lower endoscopy, but may possess malignant potential), hamartomatous polyps (which show a complex branching pattern of smooth muscle supporting normal lamina propria and glands), and inflammatory polyps. Colorectal carcinomas are one of the most frequent neoplasms in Western society; the macroscopic appearance of these lesions may be that of a polypoid vegetating mass or of a flat infiltrating lesion. Most of these tumours are adenocarcinomas (96%), that, in some cases, show a mucinous component. More rare malignancies of the large bowel include signet-ring cell carcinoma, squamous carcinoma, undifferentiated neoplasms and medullary type adenocarcinoma (solid carcinoma with minimal glandular differentiation or slight cellular pleomorphism). Colorectal carcinoma can be graded into well, moderately and poorly differentiated lesions; there is little evidence, however, that grading may be of help in evaluating prognosis of affected patients. In conclusion, colorectal tumours cover a wide range of premalignant and malignant lesions, many of which can easily be removed at endoscopy. It follows that colorectal neoplasms might be prevented by interfering with the various steps of carcinogenesis, which begins with uncontrolled epithelial cell replication, continues with the formation of adenomas of various dimensions, and eventually evolves into malignancy.

Molecular genetic alterations in hamartomatous polyps and carcinomas of patients with Peutz-Jeghers syndrome

AIM

To investigate whether mutations in the STK11/LKB1 gene and genes implicated in the colorectal adenoma-carcinoma sequence are involved in Peutz-Jeghers syndrome (PJS) related tumorigenesis.

METHODS

Thirty nine polyps and five carcinomas from 17 patients (from 13 families) with PJS were analysed for loss of heterozygosity (LOH) at 19p13.3 (STK11/LKB1 gene locus), 5q21 (APC gene locus), 18q21-22 (Smad4 and Smad2 gene locus), and 17p13 (p53 gene locus), and evaluated for immunohistochemical staining of p53. In addition, mutational analysis of K-ras codon 12, APC, and p53 and immunohistochemistry for Smad4 expression were performed on all carcinomas.

RESULTS

LOH at 19p was seen in 15 of the 39 polyps and in all carcinomas (n = 5). Interestingly, six of the seven polyps from patients with cancer had LOH, compared with nine of the 31 polyps from the remaining patients (p = 0.01). In one polyp from a patient without a germline STK11/LKB1 mutation, no LOH at 19p or at three alternative PJS candidate loci (19q, 6p, and 6q) was found. No LOH at 5q was observed. However, mutational analysis revealed an APC mutation in four of the five carcinomas. LOH at 17p was not seen in polyps or carcinomas; immunohistochemistry showed expression of p53 in one carcinoma and focal expression in three polyps. At subsequent sequence analysis, no p53 mutation was found. One carcinoma had an activating K-ras codon 12 mutation and another carcinoma showed 18q LOH; however, no loss of Smad4 expression was seen.

CONCLUSIONS

These results provide further evidence that STK11/LKB1 acts as a tumour suppressor gene, and may be involved in the early stages of PJS tumorigenesis. Further research is needed to see whether LOH in PJS polyps could be used as a biomarker to predict cancer. Differences in molecular genetic alterations noted between the adenoma-carcinoma sequence and PJS related tumours suggest the presence of a distinct pathway of carcinogenesis.

An unusual cause of rectal bleeding in a patient with cystic fibrosis

Here we identify a previously unreported cause of rectal bleeding (juvenile polyposis) in a patient with cystic fibrosis (CF). We believe this patient most likely has two coexisting genetic diseases. It also raises many issues about organ transplantation in a patient with medical conditions that individually increase the risk of gastrointestinal malignancy and stresses the diagnostic value of endoscopy in CF patients with rectal bleeding.

Hereditary non-polyposis colorectal cancer syndrome

Hereditary non-polyposis colorectal cancer (HNPCC) syndrome may account for up to 4% of the total colorectal cancer burden in our community. It is assuming an increasingly important role, both as a clinical management issue and as a model for the application of laboratory and clinical genetic services in cancer detection and prevention. Recent developments in the understanding of the molecular biology of the condition have underpinned recommendations for consideration of genetic testing for DNA mismatch repair gene mutation, recommendations that may have far-reaching implications in terms of the numbers of patients offered genetic testing and for associated costs (both financial and psychological). The aim of this review is to highlight the clinical, pathologic and molecular biologic features of HNPCC that underlie the clinical management of affected index patients and their at-risk family members.