An insight into the genetic pathway of adenocarcinoma of the small intestine

Bibliometrics analysis on the research status and trends of small bowel adenocarcinoma: 1923-2023

Objectives

The aim of this research is to discuss the research status, hotspots, frontiers, and development trends in the field of small bowel adenocarcinoma based on bibliometrics and visual analysis by CiteSpace software.

Methods

The relevant research articles on SBA from 1923 to 2023 were retrieved from the Web of Science Core Collection database. CiteSpace software was used to form a visual knowledge map and conduct analysis for the countries/regions, journals, authors, keywords, clusters, research hotspots and frontiers of the included articles.

Results

There were 921 articles included, and the number of articles published during 1923-2023 is increasing. The country with the highest number of articles published was the United States (443, 38.76%), followed by Japan (84, 9.12%) and France (72, 7.82%). The author with the highest number of publications is Ansell, Overman MJ (33, 3.58%), and the author with the highest co-citation frequency is Overman MJ (218). Journal of Clinical Oncology is the journal with the highest publication frequency. The top five cluster groups were "chemotherapy", "inflammatory bowel disease", "celiac disease", "tumor" and "small intestine". The related disease, chemotherapy drugs, and treatment regimens of SBA form the main research fields, and prognosis and diagnosis are the research hotspots and trends.

Conclusion

The global research field in SBA has expanded in the past 100 years. The prognosis and new diagnosis of SBA are hotspots in this field and require further study in the future.

Incidence, Risk Factors, and Temporal Trends of Small Intestinal Cancer: A Global Analysis of Cancer Registries

BACKGROUND & AIMS

Small intestinal cancer is a rare cancer, with limited studies exploring its epidemiology. To our knowledge, this study is the first effort to comprehensively analyze the incidence, risk factors, and trends for small intestinal cancer by sex, age, and country.

METHODS

Global Cancer Observatory, Cancer Incidence in Five Continents Plus, and Global Burden of Disease were accessed to estimate the age-standardized rates of small intestinal cancer incidence (International Classification of Diseases, 10th Revision, Clinical Modification: C17) and prevalence of lifestyle risk factors, metabolic risk factors, and inflammatory bowel disease (IBD). Risk factor associations were assessed by linear and logistic regressions. Average annual percent change was calculated using joinpoint regression.

RESULTS

A total of 64,477 small intestinal cancer cases (age-standardized rate, 0.60 per 100,000) were estimated globally in 2020, with a higher disease burden found in North America (1.4). Higher small intestinal cancer incidence was associated with higher human development index; gross domestic product; and prevalence of smoking, alcohol drinking, physical inactivity, obesity, diabetes, lipid disorder, and IBD (β = 0.008-0.198; odds ratios, 1.07-10.01). There was an overall increasing trend of small intestinal cancer incidence (average annual percent change, 2.20-21.67), and the increasing trend was comparable among the 2 sexes but more evident in the older population aged 50-74 years than in the younger population aged 15-49 years.

CONCLUSION

There was a substantial geographic disparity in the burden of small intestinal cancer, with higher incidence observed in countries with higher human development index; gross domestic product; and prevalence of unhealthy lifestyle habits, metabolic disorders, and IBD. There was an overall increasing trend in small intestinal cancer incidence, calling for the development of preventive strategies.

Microsatellite instability in the high-grade dysplasia component of duodenal adenoma is associated with progression to adenocarcinoma

PURPOSE

We examined the microsatellite instability of duodenal tumors to evaluate their molecular features associated with the adenoma-carcinoma sequence.

METHODS

Fifty-two non-ampullary duodenal epithelial tumors collected by endoscopic mucosal resection or surgical resection were studied. When a tumor had two or more dysplasia grades, the highest grade was considered. Representative areas were macro-dissected and subjected to a microsatellite instability analysis and immunohistochemical staining.

RESULTS

The 52 tumors were classified as either adenoma with low-grade dysplasia (n = 18), adenoma with high-grade dysplasia (n = 20), or adenocarcinomas (n = 14). Among these, 3 adenocarcinoma cases showed microsatellite instability and the remaining 49 tumors showed microsatellite stability. Of the 14 adenocarcinoma cases, 3 contained both high-grade dysplasia and adenocarcinoma components, and 11 contained only the adenocarcinoma component. Interestingly, all three adenocarcinoma + high-grade dysplasia cases were microsatellite instability-high in both the adenocarcinoma and high-grade dysplasia components. Immunohistochemical staining of mismatch repair proteins showed mismatch repair deficiency in three microsatellite instability-high adenocarcinoma + high-grade dysplasia cases.

CONCLUSIONS

Only adenocarcinoma cases with high-grade dysplasia components were microsatellite instability-high (in both the adenocarcinoma and high-grade dysplasia components). This suggests that microsatellite instability in the high-grade dysplasia component of duodenal adenoma is associated with progression to adenocarcinoma.

Small bowel intussusception caused by a serrated adenoma: a case report

The case was a 17-year-old young woman with a one-year history of recurrent abdominal pain and discomfort. B-scan ultrasonography identified intussusception and contrast-enhanced computed tomography of the pelvis revealed volvulus. A laparoscopic procedure was planned to identify the reason for the intussusception and obstruction. Intraoperatively, the intussusception was found to be caused by a cauliflower-shaped polypoid tumor measuring approximately 4 × 3 cm. Postoperative pathological examination identified the tumor to be a traditional serrated adenoma of the small intestine, which is rare and has atypical clinical manifestations. If unexplained abdominal pain or gastrointestinal bleeding occurs and an abdominal mass cannot be accurately located, laparoscopic or open surgery should be performed immediately. Early surgery is the most effective and reliable way of securing a prompt diagnosis and a favorable prognosis.

Interventional gastroenterology in oncology

Cancer is one of the foremost health problems worldwide and is among the leading causes of death in the United States. Gastrointestinal tract cancers account for almost one third of the cancer-related mortality globally, making it one of the deadliest groups of cancers. Early diagnosis and prompt management are key to preventing cancer-related morbidity and mortality. With advancements in technology and endoscopic techniques, endoscopy has become the core in diagnosis and management of gastrointestinal tract cancers. In this extensive review, the authors discuss the role endoscopy plays in early detection, diagnosis, and management of esophageal, gastric, colorectal, pancreatic, ampullary, biliary tract, and small intestinal cancers.

Prognostic Factors and Clinical Characteristics of Duodenal Adenocarcinoma With Survival: A Retrospective Study

Background

To evaluate the clinical risk factors that influence the overall survival in patients with duodenal adenocarcinoma (DA) after tumor resection.

Methods

This study retrospectively analyzed 188 patients who underwent tumor resection for DA between January 2005 and June 2020 at Xiangyang Central Hospital.

Results

The median survival of the patients who underwent resectional operation was 54 months, longer than of those who underwent palliative surgery (20.8 months) (2,916.17; 95% CI, 916.3−9,280.5; p < 0.001). Survival of non-ampullary duodenal carcinoma patients (50.3 months; 95% CI, 39.7−61.8) was similar to that of ampullary duodenal carcinoma patients (59.3 months; 95% CI, 38.6−66.7) but was significantly better than that of papillary adenocarcinoma patients (38.9 months; 95% CI, 29.8−54.8; p = 0.386). Those with intestinal-type ductal adenocarcinomas had a longer median overall survival than those with the gastric type (61.8 vs. 46.7 months; p < 0.01) or pancreatic type (32.2 months; p < 0.001). Clinical DA samples had significantly diverse expressions of ATG12, IRS2, and IGF2. Higher expressions of the ATG12 and IRS2 proteins were significantly correlated with worse survival. Multivariate Cox regression analysis revealed that lymph node metastasis (hazard ratio (HR), 6.44; 95% CI, 3.68−11.27; p < 0.0001), margin status (HR, 4.94; 95% CI, 2.85−8.54; p < 0.0001), and high expression of ATG12 (HR, 1.89; 95% CI, 1.17−3.06; p = 0.0099) were independent prognostic factors negatively associated with survival in patients undergoing curative resection. There was no survival difference between the groups with ampullary, non-ampullary, and papillary adenocarcinomas treated with adjuvant chemotherapy (p = 0.973).

Conclusion

Gastric/pancreatic type, high expression of ATG12, lymph node metastases, and margin status were negative prognosticators of survival in patients with DAs than in those with tumor anatomical location. Curative resection is the best treatment option for appropriate patients.

Small bowel adenocarcinoma in Crohn's disease: a systematic review and meta-analysis of the prevalence, manifestation, histopathology, and outcomes

BACKGROUND AND AIMS

Small bowel adenocarcinoma (SBA) is a rare neoplasm that is associated with Crohn's disease (CD). This study aims to quantify the prevalence of CD-SBA, review the current evidence of histopathology and molecular analysis findings, and identify the clinical presentation and outcomes of CD-SBA.

METHODS

Electronic databases Medline and Embase were searched for articles describing SBA in inflammatory bowel disease patients. The histopathology, molecular analysis findings, clinical presentation, prevalence, and outcomes of CD-SBA were extracted, and results were pooled with random effects.

RESULTS

In total, 33 articles were included in the analysis. Prevalence of SBA was 1.15 (CI: 0.31-2.33) per 1000 CD patients. Only 11% (CI: 0.04-0.21) of CD-SBA patients had observable radiological features. CD-SBA was most commonly found in the ileum (84%), diagnosed at stage 2 (36%), with main presenting complaints including obstruction, weight loss, and abdominal pain. Significant histopathological findings included adjacent epithelial dysplasia, and an equal distribution of well-differentiated (49%) and poorly differentiated subtypes (46%). Most prevalent genetic mutation was KRAS mutation (18%), followed by mismatch repair deficiency (9.7%). The 5-year overall survival for CD-SBA patients was 29% (CI: 0.18-0.41), and 33% (CI: 0.26-0.41) for de novo SBA. No statistically significant increase in risk for CD-SBA was noted for treatment with thiopurines, steroids, and 5-ASA.

CONCLUSION

Our meta-analysis found the prevalence of CD-SBA to be 1.15 per 1000 CD patients. The 5-year overall survival for CD-SBA was poor. The presenting symptoms were non-specific, and therefore the diagnosis requires a high index of suspicion.

Identification of Lynch Syndrome Carriers among Patients with Small Bowel Adenocarcinoma

Simple Summary

Small bowel adenocarcinoma (SBA) is associated with Lynch syndrome (LS). This is the first study to evaluate the identification of LS patients based on mismatch repair deficiency (MMRd) tumor among SBA. The authors found a 21.3% prevalence of MMRd tumors and a 10.1% prevalence of LS. A germline mutation was identified in 60% of patients with a MMRd tumor. This data suggests that universal tumor MMR testing among SBA patients should be implemented for the identification of LS.

Abstract

Background: Small bowel adenocarcinoma (SBA) is a rare disease which can be associated with Lynch syndrome (LS). LS tumors are characterized by the presence of microsatellite instability (MSI) and/or the loss of mismatch repair (MMR) protein expression. In SBA, the frequency of MMR deficient (MMRd) tumors varies from 5% to 35%. This study aims to describe the prevalence of LS carriers among patients with MMRd small bowel adenocarcinomas. Methods: A multicenter retrospective study with identification and MMR testing of all consecutive SBA between 2004 and 2020 in a multicenter Spanish study. Demographical data, tumor characteristics, follow-up and survival information were collected. Germline testing was driven by identification of MMRd tumors. Results: A total of 94 individuals diagnosed with SBA were recruited. We observed 20 (21.3%) MMRd tumors. In 9/15 (60%) patients with MMRd tumors, a pathogenic variant was identified (three MLH1, four MSH2, one MSH6 and one PMS2). Accordingly, the prevalence of LS among all SBA cases was 10.1%. Conclusions: More than one-fifth of SBA display MMRd and in more than a half is due to LS. Our data supports the implementation of universal MMR tumor testing among SBA for the identification of LS families.

Adenocarcinoma of the Jejunum: A Case Report and Literature Review

Small intestine cancers account for 1-3% of all gastrointestinal tumors, with only 11-25% of these tumors located in the jejunum. We report the case of a woman who has been experiencing abdominal pain for the last six months, accompanied by nausea, vomiting and appearance of dark-colored stools, who has lost 20 kg in weight during the last few months. Laboratory findings indicated anemia and no significant changes were identified in the abdominal ultrasound. By endoscopic examination of the stomach and duodenum and by colonoscopy, no infiltrations were found. Serum markers were elevated and CT scan of the abdomen showed thickening of a part of the jejunum wall with swollen lymph nodes in the mesentery, along the inferior vena cava and abdominal aorta, in the retroperitoneal space. By opening the abdominal cavity, we observed an infiltration in the initial part of the jejunum with an infiltration of the entire wall. Resection of the jejunum with related mesenthery, vessels and lymph nodes therein was performed. Histopathology revealed an invasive adenocarcinoma of the small intestine, with an invasion of all layers of the wall and mesentery. Adjuvant FOLFOX chemotherapy was introduced, 6 cycles in total, and following each cycle, tumor markers have been constantly decreasing. No relapse has been identified after nine months. Due to often deep position in the small intestine, atypical symptomatology and lack of screening, an early diagnosis is difficult. Surgical resection of the affected small intestine followed by an additional chemotherapy is the optimal treatment strategy.

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.

Therapeutic targeting of the oncogenic Wnt signaling pathway for treating colorectal cancer and other colonic disorders

The canonical Wnt pathway is one of the key cellular signaling cascades that regulates, via the transcriptional co-activator β-catenin, numerous embryogenic developmental processes, as well as tissue homeostasis. It is therefore not surprising that misregulation of the Wnt/β-catenin pathway has been implicated in carcinogenesis. Aberrant Wnt signaling has been reported in a variety of malignancies, and its role in both hereditary and sporadic colorectal cancer (CRC), has been the subject of intensive study. Interestingly, the vast majority of colorectal tumors harbor mutations in the tumor suppressor gene adenomatous polyposis coli (APC). The Wnt pathway is complex, and despite decades of research, the mechanisms that underlie its functions are not completely known. Thus, although the Wnt cascade is an attractive target for therapeutic intervention against CRC, one of the malignancies with the highest morbidity and mortality rates, achieving efficacy and safety is yet extremely challenging. Here, we review the current knowledge of the Wnt different epistatic signaling components and the mechanism/s by which the signal is transduced in both health and disease, focusing on CRC. We address some of the important questions in the field and describe various therapeutic strategies designed to combat unregulated Wnt signaling, the development of targeted therapy approaches and the emerging challenges that are associated with these advanced methods.

Minimally invasive surgery with adenocarcinoma of jejunum diagnosed pathologically before surgery: A case report

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Adenocarcinoma of jejunum is a very rare malignant tumor worldwide.

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Small intestine cancer is difficult to diagnose histologically before surgery, and whether it is diagnosed before surgery has an important influence on the surgical method.

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Multidisciplinary treatment was conducted to diagnose small intestine cancer and determine treatment options, which is a global trend.

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In this case, the preoperative balloon endoscopy was used to diagnose small intestine cancer histologically, as well as the location of the lesion, so that the operation could be performed by laparoscopy.

Introduction and importance

We report a rare case of a patient diagnosed with adenocarcinoma of the jejunum.

Presentation of case

The patient was a 58-year-old female patient who was tested for vomiting and dyspeptic symptoms at a local hospital and visited the hospital due to suspected small bowel obstruction. CT enteroscopy performed at our clinic revealed “progression of focal wall thickening in small bowel with proximal bowel dilatation”, and it was necessary to differentiate between malignant and infectious lesions. Balloon enteroscopy was planned for endoscopic observation up to the small bowel. The biopsy result was confirmed as adenocarcinoma with moderated differentiated. The patient underwent small bowel resection and anastomosis using standard laparoscopic surgery. Jejunum resection was performed by securing a safety margin of 10 cm or more, and sufficient LN dissection was also performed. The patient was discharged from the hospital without any specific complications, and as a result of pathology examination, it was confirmed as a stage 2 high risk group, and further treatment is in progress.

Clinical discussion

There are few reports of patients diagnosed with adenocarcinoma of the jejunum through symptoms of obstruction of the small intestine.

Conclusions

We report on a case of laparoscopic surgery for a rare jejunal cancer confirmed histologically before surgery.

Gastrointestinal tissue-based molecular biomarkers: a practical categorisation based on the 2019 World Health Organization classification of epithelial digestive tumours

Molecular biomarkers have come to constitute one of the cornerstones of oncological pathology. The method of classification not only directly affects the manner in which patients are diagnosed and treated, but also guides the development of drugs and of artificial intelligence tools. The aim of this article is to organise and update gastrointestinal molecular biomarkers in order to produce an easy-to-use guide for routine diagnostics. For this purpose, we have extracted and reorganised the molecular information on epithelial neoplasms included in the 2019 World Health Organization classification of tumours. Digestive system tumours, 5th edn.

Frequency and clinicopathologic associations of DNA mismatch repair protein deficiency in ampullary carcinoma: Routine testing is indicated

BACKGROUND

The significance of DNA mismatch repair (MMR) deficiency in ampullary cancers (ACs) has not been established.

METHODS

In total, 127 ACs with invasive carcinomas measuring ≥3 mmthat had adequate tissue were analyzed immunohistochemically.

RESULTS

MMR loss was detected in 18% of ACs (higher than in colorectal cancers). Twelve tumors with MLH1-PMS2 loss were negative for BRAF V600E mutation, suggesting a Lynch syndrome association. MMR-deficient tumors (n = 23), comparedwith MMR-intact tumors (n = 104), showed a striking male predominance (male:female ratio, 4.7). Although the deficient tumors had slightly larger invasion size (2.7 vs 2.1 cm), they also had more expansile growth and less invasiveness, including less perineural invasion, and they ultimately had lower tumor (T) classification and less lymph node metastasis (30% vs 53%; P = .04). More important, patients who had MMR-deficient tumors had better clinical outcomes, with a 5-year overall survival rate of 68% versus 45% (P = .03), which was even more pronounced in those who had higher Tclassification (5-year overall survival, 69% vs 34%; P = .04). MMR deficiencyhad a statistically significant association with medullary phenotype, pushing-border invasion, and tumor-infiltrating immune cells, and it occurred more frequently in ampullary-duodenal type tumors. Programed cell death-ligand 1 (PD-L1) levels analyzed in the 22 MMR-deficient ACs revealed that all medullary carcinomas were positive. Nonmedullary MMR-deficient carcinomas expressed PD-L1 in 33% of tumors cells according to the criteria for a combined positive score ≥1, but all were negative according to the tumor proportion score≥1 method.

CONCLUSIONS

In ACs, MMR deficiency is even more frequent (18%) than in colon cancer and often has a Lynch-suggestive profile, thus routine testing is warranted. Male gender, pushing-border infiltration, ampullary-duodenal origin, medullary histology, and tumor-related inflammation have a significantly higher association with MMR deficiency. MMR-deficient tumors have less aggressive behavior. PD-L1 expression is common in medullary-phenotype ACs, thus immunotherapy should be considered at least for this group.

Prognostic Significance of Stromal and Intraepithelial Tumor-Infiltrating Lymphocytes in Small Intestinal Adenocarcinoma

OBJECTIVES

Assessment of tumor-infiltrating lymphocytes (TILs) may predict the prognosis and therapeutic benefit of immunotherapy in small intestinal adenocarcinoma (SIAC) patients.

METHODS

TILs were evaluated in 231 surgically resected SIACs and compared with microsatellite instability (MSI) and clinicopathologic variables. The average number of intraepithelial TILs (iTILs) and the average density of stromal TILs (sTILs) were calculated separately.

RESULTS

High iTIL count (≥2 per high-power field) was associated with MSI-high, whereas high sTIL density (≥20% on ×200 magnification) was not. High iTIL count and high sTIL density were related to distal tumor location, medullary carcinoma, high Crohn-like lymphoid reaction counts, and fewer pancreatic invasions. SIAC patients with high iTIL count or high sTIL density had better survival than those with low values. On multivariate analysis, MSI, high sTIL density, proximal locations, lower N category, and absence of lymphovascular invasions and retroperitoneal seeding were the best independent prognostic predictors.

CONCLUSIONS

High sTIL density can be used as a prognostic indicator and high iTIL count may provide a basis for the clinical use of targeted immunotherapy in SIAC patients.

Epidemiology of Cancers of the Small Intestine: Trends, Risk Factors, and Prevention

The latest data from the United States and Europe reveal that rare small intestine cancer is on the rise, with the number of cases having more than doubled over the past 40 years in the developed world. Mortality has grown at a slower pace, thanks to improvements in early diagnosis and treatment, as well as a shift in the etiology of neoplasms affecting the small intestine. Nevertheless, 5-year survival for small intestine adenocarcinomas has lingered at only 35%. Lifestyle in developed nations, including the rise in obesity and physical inactivity, consumption of alcohol, tobacco, and red and processed meats, and occupational exposures may be to blame for the proliferation of this rare cancer. Identification of hereditary and predisposing conditions, likely to blame for some 20% of cases, may help prevent and treat cancers of the small intestine. Studies of the neoplasm have been limited by small sample sizes due to the rarity of the disease, leaving many questions about prevention and treatment yet to be answered.

Molecular Diagnostics in the Neoplasms of Small Intestine and Appendix: 2018 Update

Neoplasms of the small intestine are rare in comparison with colorectal tumors. The most common tumor types arising in the small intestine are adenocarcinomas, well-differentiated neuroendocrine tumors, gastrointestinal stromal tumors, and lymphoma. Primary appendiceal neoplasms are rare and found in less than 2% of appendectomy specimens with an incidence of approximately 1.2 cases per 100,000 people per year in the United States. This article explores molecular diagnostics in the neoplasms of small intestine and appendix.

[Diagnosis and surgical treatment of duodenal tumors]

AIM

To present the experience in diagnosis and surgical treatment of duodenal tumors.

MATERIAL AND METHODS

The study included 27 patients with different duodenal tumors: adenocarcinoma (AC, n=8), gastrointestinal stromal tumor (GIST, n=13), neuroendocrine tumor (NET, n=6). The examination included computed tomography (in 27 patients), magnetic resonance imaging (12), transcutaneous ultrasound (14), endosonography (16), esophagogastroduodenoscopy (16). All patients were operated. Conventional (18), laparoscopic (4), robot-assisted (4), endoscopic endoluminal (1) surgical interventions were performed. 17 patients were followed up from 8 months to 10 years (median 26 months).

RESULTS

According to the instrumental diagnostic methods, duodenal tumors were verified in 19 cases. Five patients with AC underwent pancreaticoduodenectomy (Whipple procedure), 2 - palliative operations (bypass gastroenteroanastomosis), 1 - explorative laparotomy. Patients with GIST underwent 3 pancreaticoduodenectomies and 10 duodenectomies: traditional (4), laparoscopic (4) and robot-assisted (2) approaches. In case of NET 3 interventions via traditional approach (pancreaticoduodenectomy, duodenal resection, tumor enucleation), 1 endoscopic endoluminal operation, 2 robot-assisted operations (duodenal resection and duodenopancreatectomy, splenectomy, distal gastrectomy) were performed. Postoperative complications occurred in 10 (37%) patients. Postoperative mortality was absent. Long-term results were analyzed in 17 patients. All patients with GIST and NET are alive without disease progression. Two AC patients are alive from those who are available.

CONCLUSION

Duodenal tumors are relatively rare. Radical surgical intervention in accordance with oncological principles is preferred for these patients. Organ-preserving procedures may be applied depending on morphological type of tumor. Examination and treatment of patients with duodenal tumors should be carried out in specialized surgical departments.

Primary small bowel adenomas and adenocarcinomas-recent advances

The small intestine represents 75% of the length and 90% of the absorptive surface area of the gastrointestinal tract (GIT), yet only 2% of digestive system cancers occur at this site. Adenocarcinoma accounts for half of small bowel malignancies. There have been a number of important recent advances in our understanding, classification and treatment of small bowel tumours. Over recent years, ampullary tumours have become recognised as a form of small bowel carcinoma, distinct from head of pancreas and lower biliary tract tumours. This is reflected in separate TNM systems and increasing interest in separating intestinal from pancreatobiliary subtypes. The recognition of the importance of microsatellite (MSI) status and the advent of molecular pathology has also changed our approach to these neoplasms.

Chemotherapy in Small Bowel Adenocarcinoma Associated with Celiac Disease: A Report of Three Cases

Tumors of the small intestine are rare and usually occur in association with genetic disease and chronic intestinal inflammation. We report three cases of small bowel adenocarcinoma in patients affected by celiac disease who received a safe chemotherapy regimen (FOLFOX IV or LV5FU2) after tumor resection.

APC:T1556fs and STK11 mutations in duodenal adenomas and adenocarcinomas

PURPOSE

Duodenal adenoma and adenocarcinoma (AC) are rare tumors, and few studies have examined their genetic features. We aimed to determine the key genetic changes in duodenal adenoma and AC, and to clarify the possible involvement of the adenoma-carcinoma sequence in duodenal tumor carcinogenesis.

METHODS

Nineteen duodenal tumors collected by endoscopic mucosal resection or surgical resection were classified as AC, adenoma with high-grade dysplasia (HGD), or adenoma with low-grade dysplasia (LGD) per the World Health Organization tumor classification. When a tumor contained two or more components with different dysplasia grades, the highest grade was assigned as the tumor grade. Representative areas of these components with different grades were microdissected and evaluated by a genomic analysis. Mutational hotspots involving 50 oncogenes and tumor suppressor genes were analyzed by next-generation sequencing, and their association with the dysplasia grade was investigated.

RESULTS

We analyzed 27 tumor components of AC or adenoma, with 11 normal mucosal samples obtained from 19 patients with duodenal tumors. The most prevalent abnormality among 50 genes tested was the KRAS mutation, which was detected in 12/19 (63.2%) patients, followed by APC and TP53 mutations (47.4 and 36.8%, respectively). According to the tumor dysplasia grading of each component, KRAS mutations were found in 5/8 (62.5%) tumors with AC components, 6/9 (66.7%) tumors with HGD components, and 3/10 (30.0%) tumors with LGD components. TP53 mutations were found in 4/8 (50.0%) tumors with AC components, 3/9 (33.3%) tumors with HGD components, and 1/10 (10.0%) tumors with LGD components. APC mutations were found in 2/8 (25.0%) tumors with AC components, 6/9 (66.7%) tumors with HGD components, and 5/10 (50.0%) tumors with LGD components. Notably, an APC:T1556fs mutation was detected in six cases (31.6%), five of which were adenoma cases. Furthermore, STK11 mutations were confirmed in 2/8 (25.0%) AC cases and in 1/11 (9.1%) adenoma cases.

CONCLUSION

APC:T1556fs and STK11 mutations found in duodenal adenomas/ACs highlight the importance of proteins encoded by these genes in tumor development. APC mutations were identified in duodenal adenomas more frequently than in duodenal ACs, which differed from the observations of typical adenoma-carcinoma sequences seen in colorectal cancer, suggesting the limited involvement of this mechanism in duodenal cancer development.

Exome-wide somatic mutation characterization of small bowel adenocarcinoma

Small bowel adenocarcinoma (SBA) is an aggressive disease with limited treatment options. Despite previous studies, its molecular genetic background has remained somewhat elusive. To comprehensively characterize the mutational landscape of this tumor type, and to identify possible targets of treatment, we conducted the first large exome sequencing study on a population-based set of SBA samples from all three small bowel segments. Archival tissue from 106 primary tumors with appropriate clinical information were available for exome sequencing from a patient series consisting of a majority of confirmed SBA cases diagnosed in Finland between the years 2003–2011. Paired-end exome sequencing was performed using Illumina HiSeq 4000, and OncodriveFML was used to identify driver genes from the exome data. We also defined frequently affected cancer signalling pathways and performed the first extensive allelic imbalance (AI) analysis in SBA. Exome data analysis revealed significantly mutated genes previously linked to SBA (TP53, KRAS, APC, SMAD4, and BRAF), recently reported potential driver genes (SOX9, ATM, and ARID2), as well as novel candidate driver genes, such as ACVR2A, ACVR1B, BRCA2, and SMARCA4. We also identified clear mutation hotspot patterns in ERBB2 and BRAF. No BRAF V600E mutations were observed. Additionally, we present a comprehensive mutation signature analysis of SBA, highlighting established signatures 1A, 6, and 17, as well as U2 which is a previously unvalidated signature. Finally, comparison of the three small bowel segments revealed differences in tumor characteristics. This comprehensive work unveils the mutational landscape and most frequently affected genes and pathways in SBA, providing potential therapeutic targets, and novel and more thorough insights into the genetic background of this tumor type.

Small bowel adenocarcinoma is a rare but aggressive disease with limited treatment options. Of gastrointestinal tumors, small bowel tumors account for 3%, of which around one third are adenocarcinomas. Due to the scarcity of evidence-based treatment recommendations there is a dire need for knowledge on the biology of these tumors. Here, we performed the first large exome sequencing effort of 106 small bowel adenocarcinomas from a Finnish population-based cohort to comprehensively characterize the genetic background of this tumor type. The set included tumors from all three small bowel segments allowing us to also compare the genetic differences between these subsets. We defined significantly mutated genes and frequently affected pathways, providing potential therapeutic targets, such as BRAF, ERBB2, ERBB3, ERBB4, PIK3CA, KRAS, ATM, ACVR2A, ACVR1B, BRCA2, and SMARCA4, for this disease.

Small Bowel Adenocarcinoma

Small bowel adenocarcinomas (SBAs) are rare tumors, but their incidence is increasing. The most common primary location is the duodenum. Even though SBAs are more often sporadic, some diseases are risk factors. Early diagnosis of small bowel adenocarcinoma remains difficult, despite significant radiologic and endoscopic progress. After R0 surgical resection, the main prognostic factor is lymph node invasion. An international randomized trial (BALLAD [Benefit of Adjuvant Chemotherapy For Small Bowel Adenocarcinoma] study) will evaluate the benefit of adjuvant chemotherapy. For metastatic disease, retrospectives studies suggest that platinum-based chemotherapy is the most effective treatment. Phase II studies are ongoing to evaluate targeted therapy in metastatic SBA.

Treatment and Survival of Small-bowel Adenocarcinoma in the United States: A Comparison With Colon Cancer

BACKGROUND

Small-bowel adenocarcinoma is rare and fatal. Because of data paucity, there is a tendency to extrapolate treatment from colon cancer, particularly in the adjuvant stetting.

OBJECTIVE

The purpose of this study was to evaluate the current surgical and adjuvant treatments of small-bowel adenocarcinoma and compare with colon cancer.

DESIGN

This was a retrospective cohort study.

SETTINGS

The linked Surveillance, Epidemiology, and End Results and Medicare database was used at a tertiary referral hospital.

PATIENTS

Patients with small-bowel adenocarcinoma and colon cancer identified from 1992 to 2010, using International Classification of Diseases for Oncology, 3 Revision, site, behavior, and histology codes were included.

MAIN OUTCOME MEASURES

Overall survival and cancer-specific survival were estimated using the Kaplan-Meier method and competing risk analysis.

RESULTS

A total of 2123 patients with small-bowel adenocarcinoma and 248,862 patients with colon cancer were identified. Five-year overall survival rates for patients with small-bowel adenocarcinoma and colon cancer were 34.9% and 51.5% (p < 0.0001). A total of 1550 patients with small-bowel adenocarcinoma (73.0%) underwent surgery, compared with 177,017 patients with colon cancer (71.1%). The proportion of patients who received chemotherapy was similar, at 21.3% for small bowel and 20.0% for colon. In contrast to colon cancer, chemotherapy did not improve overall or cancer-specific survival for patients with small-bowel adenocarcinoma, regardless of stage. Predictors of poor survival for small-bowel adenocarcinoma on multivariate analysis included advanced age, black race, advanced stage, poor tumor differentiation, high comorbidity index, and distal location. Chemotherapy did not confer additional survival benefit compared with surgery alone (HR, 1.04 (95% CI, 0.90-1.22)).

LIMITATIONS

This was a retrospective review. The reliance on Medicare data limited granularity and may have affected the generalizability of the results.

CONCLUSIONS

The prognosis for small-bowel adenocarcinoma is worse than that for colon cancer, and only surgery improves survival. In contrast to colon cancer, a survival benefit from current chemotherapy regimens for small-bowel adenocarcinoma is not seen, suggesting that it may be overused and needs more rigorous study.

Advanced small bowel adenocarcinoma: Molecular characteristics and therapeutic perspectives

Small bowel cancer represents less than 5% of all gastrointestinal cancers, while small bowel adenocarcinoma (SBA) accounts for about one third of all cancers of the small bowel. Although SBA frequently appears sporadically, some diseases are risk factors, such as Crohn's disease and some genetic predispositions to cancer. Progress in the identification of molecular alterations suggests some similarities in carcinogenesis between SBA and colorectal cancer. Evidence levels for the treatment and prognosis of these tumors are insufficient because of the scarcity of this disease and the absence of randomized trials. Chemotherapy based on fluoropyrimidine plus a platinum salt appears to be the most effective treatment regimen in non-randomized prospective trials for advanced SBA. Targeted therapy, against the angiogenic pathway or the epidermal growth factor receptor (EGFR) pathway, for example, is not yet established, but seems promising given the over-expression of vascular epithelial growth factor (VEGF)-A or EGFR observed in SBA. Phase I and II studies are currently evaluating the safety and efficacy of these targeted therapies in SBA treatment. The low incidence of SBA should promote the development of international collaborations to improve our knowledge of the biological mechanisms underlying these tumors and to set up therapeutic trials.

Insulin-Like Growth Factor II mRNA-Binding Protein 3 (IMP3) as a Useful Immunohistochemical Marker for the Diagnosis of Adenocarcinoma of Small Intestine

The biological characteristics and roles of insulin-like growth factor II mRNA-binding protein 3 protein (IMP3) expression in small-intestinal adenocarcinoma were investigated. The value of IMP3 immunostaining in the diagnosis of small-intestinal epithelial lesions was also evaluated. Immunohistochemical expression of IMP3 in normal small-intestinal mucosa adjacent to adenoma and adenocarcinoma lesions, and inflamed duodenal and ileal mucosa was analyzed. Samples assessed were: duodenal ulcer (n=6), Crohn’s disease (n=5), low-grade small-intestinal adenoma (n=10), high-grade small-intestinal adenoma (n=13), small-intestinal adenocarcinoma (n=23), lymph node metastases (LNM; n=7), and preoperative biopsies of small-intestinal adenocarcinoma (n=6). Immunohistochemical expression of Ki-67 and p53 was also analyzed in adenoma and adenocarcinoma samples. IMP3 was not expressed in normal epithelium, but weakly expressed in reparative epithelium. Meanwhile, increased IMP3 expression was associated with a higher degree of dysplasia in adenomas, higher T classification, LNM, Ki-67 positivity, histological differentiation, and lower 5-year disease-free survival, but not p53 expression in adenocarcinoma. IMP3 expression appears to be a late event in the small-intestinal carcinogenesis. Assessing the IMP3 staining pattern can be useful in the diagnosis of small-intestinal epithelial lesions when used in conjunction with other histological criteria.

Primary small-bowel malignancy: update in tumor biology, markers, and management strategies

PURPOSE

Primary small-bowel malignancies (SBM) are rare tumors but their incidence is rising. An estimated 9160 new cases and 1210 deaths due to SBM may occur in the USA in 2014. We review advances made in tumor biology, immunohistochemistry, and discuss treatment strategies for these malignancies.

METHODS

Relevant articles from PubMed/Medline and Embase searches were collected using the phrases "small-bowel adenocarcinoma, gastrointestinal carcinoids, gastrointestinal stromal tumors, small-bowel leiomyosarcoma, and small-bowel lymphoma".

RESULTS

Advances in imaging techniques such as wireless capsule endoscopy, CT and MRI enterography, and endoscopy (balloon enteroscopy) along with discovery of molecular markers such as c-kit and PDGFRA for GIST tumors have improved our ability to diagnose, localize, and treat these patients. Early detection and surgical resection offers the best chance for long-term survival in all tumors except bowel lymphoma where chemotherapy plays the main role. Adjuvant therapy with imatinib has improved overall survival for GIST tumors, somatostatin analogs have improved symptoms and also inhibited tumor growth and stabilized metastatic disease in carcinoid disease, but chemotherapy has not improved survival for adenocarcinoma.

CONCLUSIONS

Recent advances in molecular characterization holds promise in novel targeted therapies. Currently ongoing trials are exploring efficacy of targeted therapies and role of adjuvant therapy for adenocarcinoma and results are awaited. Early detection and aggressive surgical therapy for all localized tumors and lymph node sampling particularly for adenocarcinoma remains the main treatment modality.

Induction of duodenal mucosal tumors of intestinal epithelial cell origin showing frequent nuclear β-catenin accumulation similar to the concurrently induced colorectal tumors in rats after treatment with azoxymethane

Azoxymethane (AOM) is a potent carcinogen used for induction of colon tumors in rats and mice. It is also known that AOM treatment induces small bowel tumors in addition to colorectal tumors in rats. The present study examined the histogenesis of AOM-induced rat duodenal tumors in comparison with concurrently induced colorectal tumors by histochemical and immunohistochemical approaches. Duodenal and colorectal tumors were positive for both periodic acid-Schiff reaction and Alcian blue staining. Immunohistochemically, duodenal tumors were positive for intestinal epithelial markers such as cytokeratin (CK) 20 (100%) and mucin (MUC) 2 (91.7%) but negative for pancreaticobiliary markers such as CK7 (100%) and MUC1 (100%). All colorectal tumors were also negative for CK7 and MUC1 but positive for CK20. Eighty percent of colorectal tumors were positive for MUC2. In addition, nuclear accumulation of β-catenin was found in duodenal tumors (70.8%), which was similar to colorectal tumors (90.0%). These results indicate that duodenal tumors induced by AOM treatment of rats were derived from intestinal epithelium. Similar to colorectal tumors, nuclear accumulation of β-catenin indicates activation of Wnt signaling as a driving force for tumor progression in AOM-induced duodenal tumors.

Loss of ARID1A expression is associated with poor prognosis in small intestinal carcinoma

AIMS

To investigate AT-rich interactive domain-containing protein 1A (ARID1A) and p53 expression in small intestinal carcinoma (SIC) and to determine its prognostic significance.

METHODS AND RESULTS

Immunohistochemical staining for ARID1A and p53 was performed in 178 SICs using a tissue microarray (TMA). Loss of or low ARID1A expression was observed in 36 (20.2%) and 60 (33.7%) of cases, respectively. Aberrant p53 expression was observed in 99 (55.6%) cases. Loss of or low ARID1A expression was found to be associated with signet ring cell carcinoma and undifferentiated carcinoma, a high-grade tumour, and a higher T stage. No relationship was found between aberrant p53 expression and clinicopathological factors or overall survival. Patients with loss of ARID1A expression, irrespective of p53 expressional status, showed significantly poorer overall survival than those expressing ARID1A. Multiple regression analysis revealed that grade and pT stage were associated significantly with ARID1A loss, and multivariate analysis showed that patients with high ARID1A expression had a lower risk of death than those with loss of ARID1A expression.

CONCLUSIONS

Low or loss of ARID1A expression is correlated significantly with a high-grade tumour, higher T stage, and poorer overall survival. These findings suggest that ARID1A expression could be used as a prognostic marker in SIC.

Do serrated neoplasms of the small intestine represent a distinct entity? Pathological findings and molecular alterations in a series of 13 cases

AIMS

To characterize pathological, immunohistochemical and molecular features of small intestinal serrated neoplasms.

METHODS AND RESULTS

We report 13 serrated neoplasms located predominantly in the duodenum (median age, 71 years; male to female ratio, 7:6). The serrated adenomas demonstrated prominent serration, ectopic crypt formations and cytological features reminiscent of colorectal traditional serrated adenomas. Almost half the serrated adenomas demonstrated high-grade dysplasia or were associated with an adenocarcinoma. Immunohistochemical and molecular analysis showed an intestinal (CDX2-positive) phenotype in all tumours, abnormal β-catenin staining in three cases (23%), abnormal p53 expression in four cases (31%), focal loss of MGMT expression in one case (8%), KRAS mutation in five cases (38%) and CpG island methylator phenotype in six cases (50%). A diffuse pattern of Ki67 expression was present in eight adenomas (62%) and was associated with high-grade dysplasia (P = 0.02). No BRAF(V600E) mutation or loss of MLH1 expression was observed.

CONCLUSIONS

To our knowledge, this is the first series reporting serrated adenoma in the small intestine, a rare subtype of adenomas resembling traditional serrated adenoma with aggressive morphological features. The absence of the BRAF(V600E) mutation does not support a role for the serrated neoplasia pathway in the development of these lesions, as in colorectal serrated polyps.

Characterization of a new small bowel adenocarcinoma cell line and screening of anti-cancer drug against small bowel adenocarcinoma

Small bowel adenocarcinoma (SBA) is a rare, aggressive malignancy with a poor prognosis, and the mechanisms of carcinogenesis in SBA remain unclear. Our aims were to investigate the molecular mechanisms underlying SBA and to identify treatments by establishing and characterizing an SBA cell line and performing anti-cancer drug screening. SIAC1 cells, established from jejunal SBA, showed epithelial characteristics and formed organoids in 3D culture. SIAC1 cells had a heterozygous β-catenin deletion mutation, resulting in a stable β-catenin protein with enhanced Wnt/β-catenin activity. SIAC1 cells lacked MLH1 and MSH6 expression, and target genes such as TGFBR2 and ACVR2 showed frameshift mutations. Among 10 clinical SBA samples, 2 (20%) had interstitial deletions in β-catenin, expression of mismatch repair protein was aberrant in 4 (40%), and heterozygous frameshift mutations of three target genes were found in all 10 samples. On screening assay using 140 compounds, eribulin significantly inhibited SIAC1 cell growth both in vitro and in vivo by inhibition of the Wnt/β-catenin pathway via enhanced degradation of β-catenin. In conclusion, we established an SBA cell line with molecular characteristics similar to those of clinical SBA samples, including β-catenin deletion and mismatch repair protein deficiency, that will be useful for SBA research. Eribulin might be a candidate for SBA treatment due to its inhibitory effect on Wnt/β-catenin signaling.

Prognostic significance of CDX2 and mucin expression in small intestinal adenocarcinoma

The clinicopathological and prognostic significance of CDX2 and mucin expression have not been comprehensively evaluated in small intestinal adenocarcinoma. Immunohistochemical microarray analyses of CDX2, MUC1, MUC5AC, and MUC6 protein expressions in 189 surgically resected small intestinal adenocarcinoma cases were examined and compared with various clinicopathologic variables, including survival. CDX2, MUC1, MUC5AC, and MUC6 expressions were observed in 43.4% (82 patients), 37.6% (71), 31.7% (60), and 21.7% (41) of patients, respectively. Whereas CDX2 expression was found to be associated with low-grade tumors (P=0.034), fewer nodal metastases (P=0.019), and less perineural invasion (P=0.049) in small intestinal adenocarcinoma patients, patients expressing MUC1 tended to demonstrate high-grade (P=0.021) and nodular or infiltrative (P=0.020) tumors. On the basis of the combined CDX2, MUC1, MUC5AC, and MUC6 expression patterns, small intestinal adenocarcinoma patients were further classified as intestinal (CDX2+/MUC1-; 29.6%), pancreatobiliary (CDX2-/MUC1+; 23.8%), mixed (CDX2+/MUC1+; 13.8%), gastric (CDX2-/MUC1-/MUC5AC+ or MUC6+; 13.8%), or null (CDX2-/MUC1-/MUC5AC-/MUC6-; 19.0%). Among these immunophenotypes, intestinal-type patients demonstrated more frequent distal (jejunal or ileal; P=0.033), tubular (P=0.039), and low-grade tumors (P=0.004) and significantly better survival according to univariate (P<0.0001) and multivariate (P=0.001) analyses. In summary, intestinal immunophenotype adenocarcinomas are associated with distal (jejunal or ileal), tubular, and low-grade tumors and better survival outcomes. Hence, CDX2 and mucin immunohistochemical staining may provide better estimations of survival after surgical resection and intestinal immunophenotype could therefore be used as a better prognostic indicator of small intestinal adenocarcinoma.

Small bowel adenocarcinomas complicating Crohn's disease are associated with dysplasia: a pathological and molecular study

BACKGROUND

Crohn's disease (CD) is associated with an increased risk of small bowel adenocarcinoma (SBA). However, there are no guidelines for the screening and early diagnosis of SBA. Colorectal cancer associated with chronic colitis arises from dysplasia. High-risk patients benefit from surveillance colonoscopies aimed to detect dysplasia. The dysplasia-carcinoma sequence remains poorly documented in CD-associated SBA. Moreover, molecular data about SBA complicating CD and associated dysplasia are very limited. We therefore assessed dysplasia and several key molecular markers of carcinogenesis in SBA and dysplasia developed in patients with CD.

METHODS

Forty-five SBA complicating CD and 4 specimens with dysplasia without SBA were screened. In SBA, we looked for dysplasia and determined their pathological characteristics (type, grade, distribution). We also stained for mismatch repair proteins (MLH1, MSH2, MSH6, PMS2), p53, β-catenin, and p16 and looked for KRAS, BRAF and PIK3CA mutations.

RESULTS

All neoplastic lesions, except 1 lesion, were found in inflamed mucosal areas. Dysplasia was found in 20 of 41 patients with SBA (49%). Dysplasia was flat or raised, low grade or high grade, and adjacent or distant to concomitant SBA. Molecular markers of SBA carcinogenesis complicating CD were similar to those observed in chronic colitis-related colorectal cancer (KRAS, BRAF, p53, MSI), although differences were observed for β-catenin and p16. No PIK3CA mutations were observed.

CONCLUSIONS

These results suggest that there is an inflammation-dysplasia-adenocarcinoma sequence in at least half of CD-related SBA, similar to what is observed in chronic colitis-related colorectal cancer and may have implications for the prevention and treatment of this cancer.

Jejunal Cancer with WRN Mutation Identified from Next-Generation Sequencing: A Case Study and Minireview

Small bowel cancer is a rare, gastrointestinal cancer originating from the small intestines. Carcinogenesis in the jejunum, the middle segment of the small intestines, occurs less commonly than in the duodenum and ileum. Despite the increasing incidences globally, the cancer is still poorly understood, which includes lack of pathological understanding and etiological reasoning, as it seems to exhibit both similarities and differences with other types of cancers. A 76-year-old Asian man was presented with abdominal pain, which was later attributed to an adenocarcinoma in the jejunum. Initial immunoreactive staining results found no connections to colorectal cancer. The microsatellite instability test was further examined by immunohistochemistry which revealed them to be wild-type. From our exome-capture sequencing results, mutations of WRN may be important as they represent the only genetic defect in this jejunal cancer. The patient has since undergone surgical resection of his cancer and is currently being treated with chemotherapy. The pathology, genomic markers, and treatments are described along with literature review.

The analysis of microsatellite instability in extracolonic gastrointestinal malignancy

Microsatellite instability (MSI) is a genetic feature of sporadic and familial cancers of multiple sites and is related to defective mismatch repair (MMR) protein function. Lynch syndrome (LS) is a familial form of MMR deficiency that may present with a spectrum of MSI positive cancers including gastrointestinal (GI) malignancies. The incidence of high level MSI (MSI-H) in colorectal carcinoma is well defined in both familial and sporadic cases and these tumours portend a better overall prognosis in colorectal carcinoma (CRC). There are certain morphological features that suggest MSI-H CRC and international guidelines have been established for the evaluation of MSI in CRC. The prevalence and morphological features of extracolonic GI MSI-H tumours are less well documented. Furthermore, it is unclear whether the guidelines for the assessment of MSI in CRC are appropriate for application to extracolonic GI malignancies. This review aims to summarise the recent literature on MSI in extracolonic LS-related GI tract malignancies with special attention to the assessment of the MMR system by evaluation of specific microsatellite markers and/or immunohistochemical evaluation of MMR protein expression. The reported prevalence of sporadic and LS-related MSI-H tumours along with their associated unique morphological patterns and related prognostic or therapeutic implications will be discussed.

Malignant tumours of the small intestine

Adenocarcinoma, neuroendocrine tumours, sarcomas and lymphomas are the four most common malignant tumours arising in the small intestine, although over forty different histological subtypes are described. Collectively these account for only 2% of cancers of the digestive system. The incidence of small bowel cancer has increased in recent decades with a four-fold increase in carcinoid tumours. Risk factors for small bowel tumours include coeliac disease, inflammatory bowel disease and a number of genetic abnormalities. The non-specific nature of their symptoms and the difficulty in visualising these tumours with normal endoscopic techniques often results in late diagnosis. Furthermore the paucity of literature on this topic has made it difficult to standardise management. There has however been marked improvement in imaging methods resulting in earlier diagnosis in many cases. As expected, early detection of localised, well differentiated tumours followed by surgical resection with negative margins offers the best chance of long term survival. Better adjuvant treatment, notably for gastrointestinal stromal tumours, has improved 5-year survival rates significantly. Development of surveillance guidelines for at risk populations may be a valuable way of improving early diagnosis of this challenging group of conditions.

CpG island methylator phenotype and its association with malignancy in sporadic duodenal adenomas

CpG island methylator phenotype (CIMP) has been found in multiple precancerous and cancerous lesions, including colorectal adenomas, colorectal cancers, and duodenal adenocarcinomas. There are no reports in the literature of a relationship between CIMP status and clinicopathologic features of sporadic duodenal adenomas. This study sought to elucidate the role of methylation in duodenal adenomas and correlate it with KRAS and BRAF mutations. CIMP+ (with more than 2 markers methylated) was seen in 33.3% of duodenal adenomas; 61% of these CIMP+ adenomas were CIMP-high (with more than 3 markers methylated). Furthermore, CIMP+ status significantly correlated with older age of patients, larger size and villous type of tumor, coexistent dysplasia and periampullary location. MLH1 methylation was seen in 11.1% of duodenal adenomas and was significantly associated with CIMP+ tumors, while p16 methylation was an infrequent event. KRAS mutations were frequent and seen in 26.3% of adenomas; however, no BRAF mutations were detected. Furthermore, CIMP-high status was associated with larger size and villous type of tumor and race (non-white). These results suggest that CIMP+ duodenal adenomas may have a higher risk for developing malignancy and may require more aggressive management and surveillance.

Small bowel adenocarcinoma: epidemiology, risk factors, diagnosis and treatment

Small bowel adenocarcinomas are rare tumours, but their incidence is increasing. Their most common primary location is the duodenum. The few studies that have collected data regarding small bowel adenocarcinoma are not homogeneous and are widely spread over time. Even though these tumours are most often sporadic, some predisposing diseases have been identified, among which Crohn's disease and genetic syndromes. Early diagnosis of small bowel adenocarcinoma remains difficult despite significant radiological and endoscopic progress. After surgical resection the main prognostic factor is node invasion; in this case, adjuvant chemotherapy can be expected to be beneficial, although this has not been established by randomised trials. For metastatic disease, platinum-based chemotherapy seems to be the most effective treatment. Targeted therapies have not yet been evaluated in this type of cancer.

Molecular diagnostics in the neoplasms of small intestine and appendix

Adenocarcinoma of the small intestine is relatively rare in comparison to colorectal carcinoma. Adenocarcinoma of the small intestine arises through the adenoma-carcinoma sequence in the colon. However, adenocarcinomas arising in the background of inflammatory bowel disease develop through the dysplasia-carcinoma sequence. Most of the cases occur in the duodenum; however, adenocarcinoma occurring in association with Crohn disease is more common in the ileum.

Small bowel adenocarcinoma phenotyping, a clinicobiological prognostic study

BACKGROUND

Small bowel adenocarcinoma (SBA) is a rare tumour with a poor prognosis. Molecular biology data on SBA carcinogenesis are lacking.

METHODS

Expression of HER2, β-catenin, p53 and mismatch repair (MMR) protein was assessed by immunohistochemistry. KRAS, V600E BRAF mutations and microsatellite instability were investigated.

RESULTS

We obtained samples from 63 SBA patients (tumour stages: I-II: 30%; III: 35%; IV: 32%; locally advanced: 3%). HER2 overexpression (3+) was observed in 2 out of 62 patients, overexpression of p53 in 26 out of 62, abnormal expression of β-catenin in 12 out of 61, KRAS mutation in 21 out of 49, BRAF V600E mutation in 1 out of 40 patients, MMR deficiency (dMMR) in 14 out of 61 and was consistent with Lynch syndrome in 9 out of 14 patients. All of the dMMR tumours were in the duodenum or jejunum and only one was stage IV. Median overall survival (OS) was 36.6 months (95% CI, 26.9-72.2). For all patients, in univariate analysis, stages I-II (P<0.001), WHO PS 0-1 (P=0.01) and dMMR phenotype (P=0.02) were significantly associated with longer OS. In multivariate analysis, disease stage (P=0.01) and WHO PS 0-1 (P=0.001) independently predicted longer OS. For stage IV patients, median OS was 20.5 months (95% CI: 14.6; 36.6 months). In multivariate analysis, WHO PS 0-1 (P=0.0001) and mutated KRAS status (P=0.02) independently predicted longer OS.

CONCLUSION

This large study suggests that molecular alterations in SBA are closer to those in colorectal cancer (CRC) than those in gastric cancer, with low levels of HER 2 overexpression and high frequencies of KRAS mutations. The seemingly higher frequency of dMMR than in CRC may be explained by the higher frequency of Lynch syndrome in SBA patients. A dMMR phenotype was significantly associated with a non-metastatic tumour (P=0.02). A trend for a good prognosis and a duodenum or jejunum primary site was associated with dMMR.

Small bowel adenocarcinomas--existing evidence and evolving paradigms

Small bowel cancers account for 3% of all gastrointestinal malignancies and small bowel adenocarcinomas represent a third of all small bowel cancers. Rarity of small bowel adenocarcinomas restricts molecular understanding and presents unique diagnostic and therapeutic challenges. Better cross-sectional imaging techniques and development of enteroscopy and capsule endoscopy have facilitated earlier and more-accurate diagnosis. Surgical resection remains the mainstay of therapy for locoregional disease. In the metastatic setting, fluoropyrimidine and oxaliplatin-based chemotherapy has shown clinical benefit in prospective non-randomized trials. Although frequently grouped under the same therapeutic umbrella as large bowel adenocarcinomas, small bowel adenocarcinomas are distinct clinical and molecular entities. Recent progress in molecular characterization has aided our understanding of the pathogenesis of these tumours and holds potential for prospective development of novel targeted therapies. Multi-institutional collaborative efforts directed towards cogent understanding of tumour biology and designing sensible clinical trials are essential for developing improved therapeutic strategies. In this Review, we endeavour to outline an evidence-based approach to present-day management of small bowel adenocarcinoma, describe contemporary challenges and uncover evolving paradigms in the management of these rare 'orphan' neoplasias.