Colon carcinoid tumors. A population-based study

Factors associated with worse outcomes for colorectal neuroendocrine tumors in radical versus local resections

Background

Colorectal neuroendocrine tumors (NETs) are the most common NETs of the gastrointestinal tract. Due to the rarity, colorectal NETs are understudied and are not clearly understood. Our study sought to identify the factors associated with worse outcomes for colorectal NETs following resection.

Methods

We identified patients diagnosed with colorectal NETs [2004-2014] who underwent resection from the National Cancer Data Base. Non-NETs were excluded. Overall survival (OS) was evaluated using the Kaplan Meier method. Cox proportional hazards and logistic regression models were used to assess factors associated with radical versus local resection, OS and LOS.

Results

A total of 7,967 colon and 11,929 rectal NETs were analyzed. The majority of colon (93.4%) and rectal (89.1%) NETs underwent radical and local resection respectively. The 5-year OS was 69% and 92% for colon and rectal NETs respectively. Older age (OR 1.45, CI 1.37-1.53) and clinical stage 4 (OR 9.91, CI 4.56-21.52) were associated with higher odds for colonic radical resection. Lowest median income quartile (OR 1.41, CI 1.21-1.64) and African Americans (OR 1.26, CI 1.07-1.49) experienced higher mortality for colon and rectal NETs respectively.

Conclusions

Racial minority and low-income patients experience worse outcomes for colorectal NETs following resection.

Clinicopathological characteristics and frequency of multiple rectal neuroendocrine tumors: a single-center retrospective study

BACKGROUND

Rectal multiple neuroendocrine tumors (M-NETs) are rare, with only few epidemiologic reports on the topic. Therefore, their clinicopathological features are not completely known, and the appropriate treatment strategy has not been established.

PURPOSE

This study aimed to compare the clinicopathological malignant potential (lymphatic or venous invasion-positive and lymph node metastasis rates) of M-NETs with that of solitary NETs (S-NETs).

METHODS

We retrospectively investigated 369 patients with NETs of the rectum. Patients who underwent colonoscopy at the Cancer Institute Hospital between January 1979 and 2016 and diagnosed with S-NETs were included, and S-NETs were found in 348 patients. Patients with M-NETs were classified into two groups as follows: patients with < 8 tumors (several (S) group, n = 21) and those with ≥ 8 tumors (numerous (N) group, n = 3).

RESULTS

The overall frequency of M-NETs was 5.7% and that of the N group was 0.8%. The mean tumor diameter in the N group was 6.0 mm (range, 4-8 mm). The lymphatic invasion rates of the S-NETs, and S and N groups of the M-NETs were 8.9%, 5.6%, and 66.7%, respectively. Moreover, the lymph node metastasis rates were 9.2%, 11.1%, and 33.3, respectively.

CONCLUSIONS

While M-NETs in the S and N groups had different characteristics, they were rarer in the N group. The N group may have higher rates of lymphatic invasion and lymph node metastasis regardless of tumor size.

Clinicopathological features and prognostic validity of the European Neuroendocrine Tumor Society (ENETS) and American Joint Committee on Cancer (AJCC) 8th staging systems in colonic neuroendocrine neoplasms

Purpose

This study aimed to investigate the characteristics of colonic neuroendocrine neoplasms (NENs) and to validate the prognostic value of the European Neuroendocrine Tumor Society (ENETS) and American Joint Committee on Cancer (AJCC) 8th staging systems.

Methods

A total of 167 and 1248 patients with colonic NENs from 12 medical centers across China and from the Surveillance, Epidemiology, and End Results (SEER) cancer registry in the United States, respectively, were reviewed. Patients were staged according to the ENETS and AJCC 8th staging systems.

Results

Clinicopathological features of colonic NENs in the Chinese cohort and SEER cohort were significantly distinct. In both the Chinese cohort and the SEER cohort, colonic neuroendocrine carcinoma (NEC) and mixed adeno‐neuroendocrine carcinoma (MANEC) were more frequent in the midgut than in the hindgut. Tumors originating from the midgut tended to be larger and at a more advanced stage than those from the hindgut. The AJCC 8th staging system and the ENETS system appeared to have similar prognostic ability for colonic NEC/MANEC.

Conclusions

Our study revealed that tumors originating from the midgut and the hindgut shared different clinicopathological features. The AJCC 8th staging system and the ENETS system appeared to have similar prognostic ability for colonic NEC/MANEC.

Colon and Rectal Neuroendocrine Tumors: Are They Really One Disease? A Single-Institution Experience over 15 Years

Colon and rectal neuroendocrine tumors (NETs) are often studied as one entity. Recent evidence suggests that worse outcomes are associated with colon compared with rectal NETs; direct comparisons are lacking. Our aim was to assess clinicopathologic, treatment, and survival differences between these diseases. All patients who underwent resection of colorectal NETs at one institution from 2000 to 2014 were included and analyzed. Of 29 patients, 12(41%) had colon and 17 (59%) had rectal NETs. Baseline demographics were similar between groups, although colon patients tended to be symptomatic at presentation (67% vs 44%, P = 0.41). Eighty-three per cent of colon patients underwent surgical resection, whereas 77 per cent of rectal patients underwent endoscopic or transanal resection ( P = 0.003). Colon patients had larger (3.4 cm vs 0.7 cm, P = 0.03), higher T-stage (T3/T4: 91% vs 14%, P = 0.003), higher grade tumors (42% vs 12%, P = 0.09) with more lymph nodes (58% vs 24%, P = 0.12) and lymphovascular invasion positivity (58% vs 24%, P = 0.32). Five-year disease-specific survival was 53% versus 80 per cent for colon and rectal patients, respectively ( P = 0.22). After excluding high-grade tumors, colon NETs were associated with lymphovascular invasion positivity (100% vs 17%, P = 0.05) and advanced T-stage (80% vs 8%, P = 0.01). Colon and rectal 5-year disease-specific survival was 67 versus 80 per cent ( P = 0.86). Colon and rectal NETs clinically seem to be distinct entities. Colon tumors have more aggressive clinicopathologic features, which may translate to worse outcomes. These differences in tumor biology may demand distinct management and should be further studied in a multi-institutional setting.

Neuroendocrine tumors of colon and rectum: validation of clinical and prognostic values of the World Health Organization 2010 grading classifications and European Neuroendocrine Tumor Society staging systems

Background/Aims

This study evaluated and compared the clinical and prognostic values of the grading criteria used by the World Health Organization (WHO) and the European Neuroendocrine Tumors Society (ENETS). Moreover, this work assessed the current best prognostic model for colorectal neuroendocrine tumors (CRNETs).

Results

The 2010 WHO classifications and the ENETS systems can both stratify the patients into prognostic groups, although the 2010 WHO criteria is more applicable to CRNET patients. Along with tumor location, the 2010 WHO criteria are important independent prognostic parameters for CRNETs in both univariate and multivariate analyses through Cox regression (P<0.05).

Methods

Data from 192 consecutive patients histopathologically diagnosed with CRNETs and had undergone surgical resection from January 2009 to May 2016 in a single center were retrospectively analyzed.

Conclusions

Findings suggest that the WHO classifications are superior over the ENETS classification system in predicting the prognosis of CRNETs. Additionally, the WHO classifications can be widely used in clinical practice.

Neuroendocrine Carcinomas of the Gastroenteropancreatic System: A Comprehensive Review

To date, empirical literature has generally been considered lacking in relation to neuroendocrine carcinomas (NECs), the highly malignant subgroup of neuroendocrine neoplasms. NECs are often found in the lungs or the gastroenteropancreatic (GEP) system and can be of small or large cell type. Concentrating on GEP-NECs, we can conclude that survival times are poor, with a median of only 4–16 months depending on disease stage and primary site. Further, this aggressive disease appears to be on the rise, with incidence numbers increasing while survival times are stagnant. Treatment strategies concerning surgery are often undecided and second-line chemotherapy is not yet established. After an analysis of over 2600 articles, we can conclude that there is indeed more empirical literature concerning GEP-NECs available than previously assumed. This unique review is based on 333 selected articles and contains detailed information concerning all aspects of GEP-NECs. Namely, the classification, histology, genetic abnormalities, epidemiology, origin, biochemistry, imaging, treatment and survival of GEP-NECs are described. Also, organ-specific summaries with more detail in relation to disease presentation, diagnosis, treatment and survival are presented. Finally, key points are discussed with directions for future research priorities.

Surgical resection of hepatic and cardiac neuroendocrine metastases from a caecal primary tumour

A 66-year-old patient had an incidentally detected caecal neuroendocrine tumour that had metastasised to the liver and left atrium. He was asymptomatic with regard to this tumour and did not have carcinoid syndrome. Resection of the primary tumour and the metastatic deposits (with the ablation of one lesion) is thought to be curative.

Clinicopathologic characteristics of colonic carcinoid tumors

BACKGROUND

Extra-appendiceal colonic carcinoids are uncommon neuroendocrine tumors with a poor prognosis compared with carcinoids of other gastrointestinal origins. Few studies have examined the clinicopathologic profile and behavior of this rare tumor.

MATERIALS AND METHODS

A retrospective analysis was performed on patients with colonic carcinoid tumors evaluated at a single tertiary care center between 1996 and 2012. Collected data included patient and tumor characteristics, presentation, treatment, recurrence, and survival. Results were integrated into a comprehensive review of the colonic carcinoid literature.

RESULTS

In total, 114 patients with colorectal carcinoid tumors were identified, and 15 patients with extra-appendiceal tumors were analyzed. The mean age was 58.6 ± 3.0 y, and subjects were predominantly male (73.3%). The most common presenting problem was abdominal pain (33.3%), although 26.7% of patients were asymptomatic. Cecal tumors were the most prevalent (73.3%), and most patients underwent right hemicolectomy. Three patients with lesions < 1 cm were treated endoscopically. The mean tumor diameter was 2.9 ± 0.5 cm, with lymph node or distant metastasis present in 53.3% and 26.7%, respectively. All but two patients underwent a presumed curative resection. During a mean follow-up of 4.2 ± 1.0 y, there was only one death (non-carcinoid specific). Eleven patients were alive without evidence of disease at last follow-up and three patients were alive with disease, one of whom initially had a presumed curative resection that recurred.

CONCLUSIONS

This case series further elucidates the clinicopathologic characteristics of colonic carcinoid tumors, which aids physicians in guiding the diagnosis and management of these rare tumors.

The management of gastrointestinal tract malignancies

Surgery is the mainstay of treatment for many patients with malignancies of the gastrointestinal (GI) tract. The coordination of patient care and timing of surgical intervention require a multidisciplinary approach. It is not unusual for GI malignancies to be discovered in a hospital setting; patients with these malignancies are frequently admitted and discharged from nonsurgical services. Therefore, it is imperative that all physicians involved in the care of patients with GI malignancies have knowledge regarding the workup and surgical treatment of GI tract lesions. This article is a brief overview of the workup and surgical management of malignancies of the GI tract.

Treatment strategy for rectal carcinoids: a clinicopathological analysis of 229 cases at a single cancer institution

BACKGROUND AND AIM

A treatment strategy for tumors with only venous invasion and characteristics of small rectal carcinoids with metastasis have not been clearly documented. The present study aims to determine the risk factors for lymph node metastasis and to elucidate characteristics of small tumors with metastasis.

METHODS

We investigated a total of 229 patients with rectal carcinoids. The relationship between each clinicopathological variable and the presence of lymph node metastasis was evaluated.

RESULTS

Tumor size (larger than 10 mm), presence of central depression, depth of tumor invasion, lymphatic invasion, and venous invasion were significantly associated with the incidence of lymph node metastasis (P < 0.001). Multivariate analysis revealed that tumor size (odds ratio: 63.3, P < 0.001) and venous invasion (odds ratio: 40.9, P < 0.001) were independently predictive of lymph node metastasis. In 204 patients with small (no larger than 10 mm) tumors, 10 patients had lymph node metastasis. All 10 tumors had low proliferation values indicated by mitosis and Ki-67 index. Multivariate analysis for the 204 patients revealed that only venous invasion was independently associated with metastasis (odds ratio: 40.1, P < 0.001). Five-year disease free survival rates of the total patients with metastasis and without metastasis were 81.1% and 95.5%, respectively (P < 0.001, log-rank test).

CONCLUSIONS

Venous invasion as well as tumor size and lymphatic invasion indicates high malignant potential to metastasize to lymph node and would provide useful information in considering the addition of radical surgery. Postoperative pathological examinations of specimens obtained by local resection are very important to avoid underestimation.

Neuroendocrine tumors of the colon and rectum: prognostic relevance and comparative performance of current staging systems

BACKGROUND

With increasing interest in neuroendocrine tumors (NETs), three staging systems for NETs of the colon and rectum have been published. Their prognostic relevance has not been examined and compared in an independent clinical database.

METHODS

From the National Cancer Database (NCDB), 5457 patients diagnosed with colorectal neuroendocrine tumor (CRNETs) between 1998 and 2002 were staged according to the staging systems from (1) European Neuroendocrine Tumor Society (ENETS, 2006; n = 1537); (2) American Joint Committee on Cancer (AJCC, 2009; n = 1140); and (3) location-specific staging systems from the Surveillance Epidemiology and End Results (SEER, 2008; n = 942). Stage-stratified overall survival (OS) and Cox-specific concordance indices were calculated for each system. Independent prognostic factors were identified by multivariate analysis.

RESULTS

Five-year OS for stage I, II, III, and IV CRNETs as defined by the ENETS staging system were 90.8, 77.3, 53.1, and 14.8 %, respectively. For well-differentiated CRNETs, the 5-year OS for stage I, II, III, and IV as defined by the AJCC staging system were superior: 90.6, 83.9, 64.8, and 24.9 %, respectively. Both staging systems had a concordance index of 0.72. After specifying location in the colon versus rectum, all three systems demonstrated acceptable performance. Histologic grade was a significant independent predictor of OS not currently incorporated in the staging systems.

CONCLUSIONS

The three staging systems showed comparable prognostic stratification of CRNETs, while the AJCC and ENETS systems are the most parsimonious. The current analysis supports the use of the AJCC for well-differentiated disease and ENETS systems for all CRNETs until there is further evidence for modification.

Management of gastrointestinal carcinoid tumours - 10 years experience at a district general hospital

BACKGROUND

There is paucity of guidelines regarding management of gastrointestinal carcinoid tumours in district hospitals.

METHODS

This study was undertaken at a district hospital to analyse the management pathway of gastrointestinal carcinoid tumours.

RESULTS

Over a period of 10 years there were 35 patients, with an estimated annual incidence of 2.5 per 100,000 population. After a median follow up of 24 months, 22 (63%) patients were alive and disease free. Only 56% patients were referred to the regional neuro-endocrine multidisciplinary team.

CONCLUSIONS

Management of patients with carcinoid tumours in district hospitals needs streamling with increased utilisation of regional neuroendocrine multidisciplinary teams.

Tumor size and depth predict rate of lymph node metastasis in colon carcinoids and can be used to select patients for endoscopic resection

BACKGROUND

Regional lymphadenectomy is recommended for all colon carcinoids, whereas resection without lymphadenectomy is accepted for selected appendiceal and rectal carcinoids. We examined the relation of tumor size and depth to lymph node metastasis in order to determine whether colon carcinoids could be selected for endoscopic resection.

METHODS

Patients were identified from the Surveillance Epidemiology and End Results Registry. The Pearson chi-square and the log rank tests were used. P < 0.05 was considered significant.

RESULTS

We identified 929 patients who underwent resection of localized colon carcinoids without distant metastasis diagnosed from 1973 to 2006. The diagnosis of small and superficial tumors increased over time (p < 0.001). The presence of lymph node metastasis was adversely associated with survival (p < 0.001); however, there was only a trend toward independence on multivariate analysis (p = 0.054). Tumor size and depth were associated with lymph node metastasis (p < 0.001, p < 0.001). Tumors were subgrouped by size and depth to find cases with a low risk of lymph node metastasis. Intramucosal tumors < 1 cm had a 4% rate of lymph node metastasis, while all other subgroups had rates ≥ 14%.

CONCLUSION

Tumor size and depth predict lymph node metastasis for colon carcinoids. Endoscopic resection may be appropriate for intramucosal tumors <1 cm.

Pathology of Gastrointestinal Neuroendocrine Tumors: An Update

Gastrointestinal (GI) neuroendocrine tumors (NETs) are a heterogeneous group of relatively slow-growing neoplasms with marked site-specific differences in hormonal secretion and clinical behavior. Most are sporadic neoplasms, with only 5% to 10% arising in patients with hereditary disorders, most commonly in multiple endocrine neoplasia type 1. Although a uniform terminology is not universally accepted, use of the 4-category WHO classification of these tumors is becoming more widespread, and recommendations for tumor grading and staging have been recently formulated. Most GI NETs are easily recognized on routine histologic examination; rarely, a limited panel of immunohistochemical markers may be useful in establishing the diagnosis. This article describes general and site-specific features of these tumors and outlines potential pitfalls in diagnosis.

Carcinoid and neuroendocrine tumors of the colon and rectum

Carcinoid and neuroendocrine tumors of the colon and rectum arise from the amine precursor uptake and decarboxylation (APUD) cells of the intestine. Carcinoid tumors are most commonly found in the gastrointestinal tract and are located in decreasing order of frequency in appendix, ileum, rectum, stomach, and colon. The vast majority of lesions are asymptomatic and are found incidentally during endoscopy. The management of these lesions depends upon the size of the lesion, involvement of the muscularis, location, and presence of metastatic disease. Small lesions (1 cm) can often be treated locally, either endoscopically or transanally. However, larger lesions (> 2 cm) require a formal oncologic resection. Adjuvant therapy is indicated only for metastatic disease, and admirable advances have been made in the realm of chemotherapy for reduction of disease and palliation of the symptoms of carcinoid syndrome. In this article, we discuss the nature of these interesting and uncommon tumors, clinical presentation, treatment options, and prognosis.

Pathologic research update of colorectal neuroendocrine tumors

Colorectal neuroendocrine tumors (NETs) originate from neuroendocrine cells in the intestinal tract, and represent a small area within oncology, but one which has provided increasing new data during the past years. Although the World Health Organization has determined clinical and histological features to predict prognosis for such tumors, they may not be valid on an individual basis. We aim to give an overview of the recent findings with regard to pathology, molecular genetics and diagnosis of NETs.

Carcinoid tumors of the gastrointestinal tract

The gastrointestinal tract is the largest neuroendocrine system in the body. Carcinoid tumors are amine precursor uptake decarboxylase (APUD) omas that arise from enterochromaffin cells throughout the gut. These tumors secrete discrete bioactive substances producing characteristic immunohistochemical patterns. Most tumors are asymptomatic and detected at late stages. Hepatic metastases are commonly responsible for carcinoid syndrome. The small bowel is the most common location of carcinoids. Computed tomography scan and magnetic resonance imaging are useful in the detection of these tumors. The measurement of bioactive amines is the initial diagnostic test. Various treatment options, including somatostatin analogs, interferon, chemotherapy, surgery, hepatic artery chemoembolization, and surgery have emerged in the past two decades. However, the incidence and prevalence of carcinoid tumors has increased, while mean survival time has not changed significantly. The lack of standardized classification, federal support, and an incomplete understanding of the complications of this disease are some of the impediments to progress in treatment.

Colonic carcinoid tumors: a clinicopathologic study of 23 patients from a single institution

CONTEXT: Colonic carcinoids, excluding those arising in the appendix, have proved to be extremely rare. Due to their rarity, the characteristics and behavior of this unusual malignancy remain unclear. OBJECTIVE: To review the clinicopathologic features of patients operated on carcinoid tumors of the colon. METHODS: Twenty-three patients (12 males and 11 females) were operated on colonic carcinoids. The mean age of the patients was 63.0 ± 12.9 years (42 to 85 years). The clinical and histopathological data of patients who were pathologically diagnosed as having carcinoid tumors and submitted to surgical treatment over a 30-year period (1977-2007) were gathered. Actuarial patient survival was estimated using the Kaplan-Meier method, with carcinoid-specific death as the outcome. RESULTS: The mean time elapsed between onset of symptoms and surgical treatment was 8.3 months (1.5 to 20 months). The most frequent symptoms or signs encountered were abdominal pain followed by anorexia or weight loss, diarrhea, abdominal tenderness, palpable abdominal mass, and rectal bleeding. No carcinoid syndrome was noted. The lesion was located in the cecum in 16 (69.6%) patients, in the sigmoid in 3 patients (13.0%), in the ascending colon in 3 patients (13.0%), and in the transverse colon in one patient (4.3%). Twenty-one (91.3%) patients were operated on curative intent. Spreading of the disease to the liver and peritoneum was found in two (8.7%) patients who submitted to intestinal bypass. The mean size of the largest mass was 3.7 ± 1.2 cm (1.5 to 6.2 cm). There were multiple (two or more) lesions in three cases (13.0%). In the resected cases, the lymph nodes were compromised in 10 patients (47.6%) and disease-free in 11 (52.4%). Venous invasion and neural infiltration were both present in five (23.8%) patients. The tumors had penetrated the muscularis propria in all resected cases. Four (17.4%) patients had a second non-carcinoid primary tumor. Three (13.0%) patients died due to postoperative complications and five (21.7%) patients died from metachronous metastases or local recurrence. Fifteen patients (65.2%) remain alive without evidence of active disease. The mean follow-up period was 12 years (1.2 to 18 years), whereas the mean global survival was 50.7 ± 34.2 months and the crude survival rate at 5 years was 62.7%. CONCLUSIONS: Carcinoid tumors of the colon are frequently right-sided and may be clinically occult until an advanced stage is reached. Based on the relatively poor survival rates reported, it is recommended that, in addition to standard surgical resection, vigorous surveillance for metastatic disease must be performed, particularly during the first 2 years after surgery. In addition, these patients require evaluation of the entire gastrointestinal tract for evidence of coexisting malignancy, along with an extended period of follow-up, because tumor recurrences after 5 years are not uncommon.

[Endoscopic diagnosis of gastroenteropancreatic neuroendocrine tumors]

Gastroenteropancreatic endocrine tumors can be broadly divided into two groups: pancreatic endocrine tumors and carcinoid tumors. In both types of tumor, patients can present with a clinical syndrome related to hormone secretion by the tumor. Due to the location of these tumors, the various endoscopic techniques play a major role in their localization and histological and cytological confirmation, and even in their endoscopic resection. The present article describes the endoscopic procedures available for the localization and management of these tumors.

Carcinoid tumors

Carcinoid tumors are rare, slow-growing neuroendocrine tumors arising from the enterochromaffin cells disseminated throughout the gastrointestinal and bronchopulmonary systems. Though they have been traditionally classified based on embryologic site of origin, morphologic pattern, and silver affinity, newer classification systems have been developed to emphasize the considerable clinical and histopathologic variability of carcinoid tumors found within each embryologic site of origin. These neoplasms pose a diagnostic challenge because they are often innocuous at the time of presentation, emphasizing the need for a multidisciplinary diagnostic approach using biochemical analysis, standard cross-sectional imaging, and newer advances in nuclear medicine. Similarly, treatment of both primary and disseminated carcinoid disease reflects the need for a multidisciplinary approach, with surgery remaining the only curative modality. The prognosis for patients with these tumors is generally favorable; however, it can be quite variable and is related to the location of the primary tumor, extent of metastatic disease at initial presentation, and time of diagnosis.

A population-based study of colorectal cancer histology in the United States, 1998-2001

BACKGROUND

Histology is an important factor in the etiology, treatment, and prognosis of cancer. The purpose of this study was to descriptively characterize colorectal cancer (CRC) histology in the United States population.

METHODS

Data from cancer registries in the National Program of Cancer Registries (NPCR) or Surveillance, Epidemiology and End Results (SEER) program, representing 88% of the U.S. population, were used in the study. The analysis included 522,630 microscopically confirmed CRC cases diagnosed from 1998-2001.

RESULTS

About 96% of CRCs were adenocarcinomas, approximately 2% were other specified carcinomas (including carcinoid tumors), about 0.4% were epidermoid carcinomas, and about 0.08% were sarcomas. The proportion of epidermoid carcinomas, mucin-producing carcinomas, and carcinoid tumors was greater among females. Several histologic patterns with regard to race and ethnicity existed, including a higher percentage of carcinoid tumors among most non-white populations. With respect to age, higher percentages of sarcomas, mucin-producing adenocarcinomas, signet ring cell tumors, and carcinoid tumors were found in individuals under age 40. Overall, adenocarcinomas were more likely to be diagnosed at regional stages with moderate differentiation. Compared with other adenocarcinomas, signet ring cell tumors were more often poorly differentiated and were at distant stage at diagnosis. Carcinoid tumors and sarcomas were mainly poorly differentiated and were at localized stage at diagnosis. Small cell carcinomas were more likely undifferentiated and were at distant stage at diagnosis.

CONCLUSIONS

To date, this is the largest population-based study to analyze CRC histology in the United States. Distinct demographic and clinical patterns associated with different histologies may be helpful for future epidemiologic, laboratory, and clinical studies.

Treatment of neuroendocrine tumors with somatostatin analogs

Neuroendocrine tumors constitute a group of hormone producing tumors originating from neuroendocrine cells in different organs. Most tumors have a low proliferation index measured by Ki67 and the progression of the tumor is slow. However, many patients suffer from endocrine symptoms induced by the hormones produced and released by the tumor cells. For some patients these symptoms can be life- threatening as in midgut carcinoid patients suffering from carcinoid crises with extensive flushes and hypotension or in patients with severe diarrhea induced by tumors producing vasointestinal polypeptide. In many other patients the hormone-induced symptoms interfere with the ability to carry out ordinary daily activities. The introduction of somatostatin analogs in the treatment of these hormone related symptoms has made it possible to control most of them and has added significantly to the quality of life for this group of patients. Unfortunately, the clinical inhibitory effect on tumor growth has not been very good with only 5-10% of the patients showing an objective response. However, stabilization of tumor growth may be achieved in a significant number of patients. In the future, the hope is that development of new somatostatin analogs with broader receptor-binding profiles will give us new analogs which are more efficient with regard to their antiproliferative effect. This possibility will be studied in future trials.

Management of Less Common Tumors of the Colon, Rectum, and Anus

The majority of colorectal and anal malignancies are adenocarcinomas and squamous cell cancers, respectively. Despite the predominance of these neoplasms in these locations, rare histiotypes of the colon, rectum, and anus do occur. These histotypes include but are not limited to lymphoma, melanoma, diffuse cavernous hemangioma, and sarcomas, such as leiomyosarcoma or Kaposi's sarcoma. These tumors often present challenges to clinicians with respect to diagnosis, staging, management, and pathology because of their unfamiliarity. A Medline search using "colon," "rectum,""anus," "lymphoma," "melanoma," "diffuse cavernous hemangioma," "squamous cell carcinoma," "carcinoid," "sarcoma," "leiomyosarcoma," "Kaposi's sarcoma," "Paget's disease," "Bowen's disease," and "basal cell carcinoma" as key words was performed as well as a cross-referencing of the bibliography cited in each work. Rare tumors of the colon, rectum, and anus present diagnostic and management dilemmas for clinicians. Because of their infrequency and poor prognosis, the optimal management of these tumors is controversial. For some histotypes, such as squamous cell carcinoma and carcinoids of the rectum, treatment depends on location and size of the tumor. For uncommon anal lesions, such as Bowen's disease, Paget's disease, and basal cell carcinoma, wide local excision (WLE) with negative margins is the standard of care. For other lesions such as anorectal melanoma or leiomyosarcoma, abdominal perineal resection versus WLE is still being debated. Because the optimal treatment of these tumors is still unclear, we recommend a multidisciplinary approach including a surgeon, primary care physician, medical oncologist, radiation oncologist, and pathologist to offer the patient the best outcome.

Current status of gastrointestinal carcinoids

Gastrointestinal (GI) carcinoids are ill-understood, enigmatic malignancies, which, although slow growing compared with adenocarcinomas, can behave aggressively. Carcinoids are classified based on organ site and cell of origin and occur most frequently in the GI (67%) where they are most common in small intestine (25%), appendix (12%), and rectum (14%). Local manifestations--mass, bleeding, obstruction, or perforation--reflect invasion or tumor-induced fibrosis and often result in incidental detection at emergency surgery. Symptoms are protean (flushing, sweating, diarrhea, bronchospasm), usually misdiagnosed, and reflect secretion of diverse amines and peptides. Biochemical diagnosis is established by elevation of plasma chromogranin A (CgA), serotonin, or urinary 5-hydroxyindoleacetic acid (5-HIAA), while topographic localization is by Octreoscan, computerized axial tomography (CAT) scan, or endoscopy/ultrasound. Histological identification is confirmed by CgA and synaptophysin immunohistochemistry. Primary therapy is surgical excision to avert local manifestations and decrease hormone secretion. Hepatic metastases may be amenable to cytoreduction, radiofrequency ablation, embolization alone, or with cytotoxics. Hepatic transplantation may rarely be beneficial. Chemotherapy and radiotherapy have minimal efficacy and substantially decrease quality of life. Intravenously administered receptor-targeted radiolabeled somatostatin analogs are of use in disseminated disease. Local endoscopic excision for gastric (type I and II) and rectal carcinoids may be adequate. Somatostatin analogues provide the most effective symptomatic therapy, although interferon has some utility. Overall 5-year survival for carcinoids of the appendix is 98%, gastric (types I/II) is 81%, rectum is 87%, small intestinal is 60%, colonic carcinoids is 62%, and gastric type III/IV is 33%.

Prognostic indicators for carcinoid neuroendocrine tumors of the gastrointestinal tract

Factors that determine the clinical course and outcome of patients with gastrointestinal (GI) carcinoid tumors are complex and multifaceted. These include the site of origin within the GI tract, the size of the primary tumor, and the anatomical extent of disease, whether localized, regional, or metastatic to distant sites. The new World Health Organization (WHO) histological classification of endocrine tumors, including carcinoids, represents a significant advance in terms of providing a consistent framework for histopathological interpretation that should facilitate multicenter research on treatment outcomes. Histochemical indicators of a poorer prognosis are the degree of expression of the proliferation protein Ki-67 and the p53 tumor suppressor protein. Adverse clinical indicators are the malignant carcinoid syndrome, carcinoid heart disease, and high concentrations of the tumor markers, urinary 5-HIAA and plasma chromogranin A.

Comparison of Cox's and relative survival models when estimating the effects of prognostic factors on disease-specific mortality: a simulation study under proportional excess hazards

In many prognostic studies focusing on mortality of persons affected by a particular disease, the cause of death of individual patients is not recorded. In such situations, the conventional survival analytical methods, such as the Cox's proportional hazards regression model, do not allow to discriminate the effects of prognostic factors on disease-specific mortality from their effects on all-causes mortality. In the last decade, the relative survival approach has been proposed to deal with the analyses involving population-based cancer registries, where the problem of missing information on the cause of death is very common. However, some questions regarding the ability of the relative survival methods to accurately discriminate between the two sources of mortality remain open. In order to systematically assess the performance of the relative survival model proposed by Esteve et al., and to quantify its potential advantages over the Cox's model analyses, we carried out a series of simulation experiments, based on the population-based colon cancer registry in the French region of Burgundy. Simulations showed a systematic bias induced by the 'crude' conventional Cox's model analyses when individual causes of death are unknown. In simulations where only about 10 per cent of patients died of causes other than colon cancer, the Cox's model over-estimated the effects of male gender and oldest age category by about 17 and 13 per cent, respectively, with the coverage rate of the 95 per cent CI for the latter estimate as low as 65 per cent. In contrast, the effect of higher cancer stages was under-estimated by 8-28 per cent. In contrast to crude survival, relative survival model largely reduced such problems and handled well even such challenging tasks as separating the opposite effects of the same variable on cancer-related versus other-causes mortality. Specifically, in all the cases discussed above, the relative bias in the estimates from the Esteve et al.'s model was always below 10 per cent, with the coverage rates above 81 per cent.

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.

Neuroendocrine carcinoma of the sigmoid colon: report of a case

Neuroendocrine carcinoma of the colon is a rare entity; however, this type of tumor is known for its aggressive progression and poor prognosis. A case of a 56-year-old Japanese male is presented in this report. A huge, child's head-sized tumor was found to have grown extraluminally on the sigmoid colon with multiple liver metastases. The tumor measured 16.5 x 15 x 8.2 cm in size and weighed 1 300 g. The patient died of hepatic failure due to massive liver metastases 6 months after operation. The pathological findings including an electron microscopic analysis were correlated with those of neuroendocrine carcinoma. We reviewed the English literature, and analyzed 94 cases of neuroendocrine carcinoma which had been reported previously. The nomenclature and definition of this disease still remains somewhat unclear, and not a small population of this disease may thus have been misdiagnosed and treated as other less aggressive entities. The necessity to make an accurate differential diagnosis in such cases is thus emphasized.

Review article: current status of gastrointestinal carcinoids

Carcinoid tumours are enigmatic, slow growing malignancies which occur most frequently (74%) in the gastrointestinal tract. In recent years, it has become apparent that the term 'carcinoid' represents a wide spectrum of different neoplasms originating from a variety of different neuroendocrine cell types. Carcinoid lesions are usually identified histologically by their affinity for silver salts, by general neuroendocrine markers, or more specifically by immunocytochemistry using antibodies against their specific cellular products. Within the gut, the most frequent sites are the small bowel (29%), the appendix (19%) and rectum (13%). Clinical manifestations are often vague or absent. Nevertheless, in approximately 10% of patients the tumours secrete bioactive mediators which may engender various elements of characteristic carcinoid syndrome. In many instances the neoplasms are detected incidentally at the time of surgery for other gastrointestinal disorders. The tendency for metastatic spread correlates with tumour size, and is substantially higher in lesions larger than 2.0 cm. An association with noncarcinoid neoplasms is ascribed in 8-17% of lesions. Treatment consists of radical surgical excision of the tumour, although gastric (type I and II) and rectal carcinoids may be managed with local excision. Overall 5-year survival is excellent for carcinoids of the appendix (86%) and rectum (72%), whereas small intestinal (55%), gastric (49%) and colonic carcinoids (42%) exhibit a far worse prognosis.

Gastrointestinal carcinoid tumors: current management strategies

BACKGROUND

Carcinoid or neuroendocrine tumors of the gastrointestinal tract, although characteristically indolent, are also quite heterogeneous both with respect to histologic and endocrine features and with respect to clinical presentation and behavior.

PURPOSE

This study was undertaken to review and summarize the current literature on classification controversies, site-specific carcinoid presentation and behavior, and diagnostic and management strategies for primary and advanced carcinoid tumors and the carcinoid syndrome.

RESULTS

For carcinoid tumors, oncologic results depend on the location of the primary tumor, extent of locoregional and metastatic disease, functioning status of the tumor, and the feasibility of complete surgical extirpation. Whereas favorable survival rates are typically observed for appendiceal and rectal primaries, less favorable rates are often observed for colonic and ileal tumors. A search for additional tumors is generally advised because multiple carcinoids and second neoplasms are not uncommon. Because of the indolent nature of the tumor and because these therapies have been shown to improve quality and quantity of life, otherwise fit patients with advanced carcinoid disease should be treated with aggressive medical and surgical therapies. Development of a malignant carcinoid syndrome indicates the presence of a functionally active carcinoid tumor and portends a poor prognosis.

CONCLUSION

Gastrointestinal carcinoids, although malignant, behave differently from other carcinomas. Results are highly variable and must be individualized according to the site of the primary tumor, extent of spread, and general condition of the patient. A prolongation of quality life can often be accomplished through aggressive medical and surgical therapies.

Neuroendocrine gastrointestinal tumours

Neuroendocrine gut and pancreatic tumours have provided a diagnostic and therapeutic challenge over the years. These rather slowly growing neoplasms have been assigned a good prognosis but when liver metastases are present the prognosis is not better than that of most other malignant tumours. Despite the development of improved diagnostic procedures many patients are still referred at a stage of the disease too late for surgical cure, at which time medical treatment is warranted. The diagnosis is based on histopathological diagnosis including silver stainings (Grimelius, Masson) and immunohistochemistry for chromogranin A and synaptophysin. Analysis of chromogranin A in the plasma is an important adjunct in the screening for various types of neuroendocrine gut and pancreatic tumours. About 80%-100% of patients with verified neuroendocrine gastrointestinal tumours have elevated circulating levels of this glycoprotein. Depending on clinical symptoms the chromogranin A analysis is supplemented by other peptide hormone analyses as well as urinary 5-HIAA for patients with midgut carcinoid tumours. In the past the localization procedures were based on CT, MRI and ultrasound investigations but in recent years somatostatin receptor scintigraphy (octreoscan) and endoscopic ultrasonography have significantly improved the diagnostic potential. Almost 80% of neuroendocrine gastrointestinal tumours present somatostatin receptor subtype 2 binding 111Indium-labelled octreotide which can be used for staging of the disease, and which also indicates whether or not somatostatin analogues can be used in the treatment of these tumours. Surgery is still a cornerstone in the treatment of neuroendocrine gastrointestinal tumours, even if the patients are beyond cure. Debulking procedures and bypassing operations are important for improving clinical condition and facilitating impending medical treatment, and during the past decade a more aggressive surgical approach has emerged. The medical treatment is based on chemotherapy, and the use of somatostatin analogues and alpha-interferons. Chemotherapy, in particular the combination of streptozotocin with 5-FU or doxorubicin, is still first-line treatment for most endocrine pancreatic tumours, while somatostatin analogues and alpha-interferons are considered first-line for classical midgut carcinoids. Chemotherapy and biotherapy can be combined in many patients, and changes from one medical treatment to another during the course of the disease is mandatory for control of the disease. It is important to realise that most patients with malignant tumours are not cured by medical treatment but that the disease can be controlled for extended periods of time. In the future it will be possible to individualize treatments on the basis of new information about such features of tumour biology as proliferation capacity, expression of adhesion molecules, and growth factors and their receptors.