Viability of endoscopic and excisional treatment of early rectal carcinoids

Diagnostic performance and impact on patient management of [68Ga]Ga-DOTA-TOC PET/CT in colorectal neuroendocrine tumors derived from hindgut

The main purpose of this retrospective study was to determine the diagnostic performance of [68Ga]Ga-DOTA-D-Phe1-Try3-octreotide(DOTA-TOC) positron emission tomography/computed tomography (PET/CT) in patients with well-differentiated colorectal Neuroendocrine Tumours (NETs) originating from the hindgut. The other aims were to assess the impact of the examination on patient management and to analyze the results of 2-[18F]FDG and/or 6-[18F]FDOPA PET/CT when they were performed. [68Ga]Ga-DOTA-TOC PET/CT and clinical data from 30 patients with biopsy-proven well-differentiated NETs originating from the hindgut were retrospectively reviewed and analyzed by comparing the [68Ga]Ga-DOTA-TOC PET/CT findings with pathological and/or follow-up data. We also compared the [68Ga]Ga-DOTA-TOC PET/CT results with 2-[18F]FDG and/or 6-[18F]FDOPA PET/CT results in 6 patients. The impact on management was determined in hindsight by comparing the patient management decided before and after the TEP examination based on data from multidisciplinary team meetings. On a patient basis, [68Ga]Ga-DOTA-TOC PET/CT was accurate in 30 of the 30 examinations. [68Ga]Ga-DOTA-TOC PET/CT correctly identified the primary tumor in all patients with primary tumors not resected before the examination and allowed the detection of unexpected distant metastases in 36% of the patients referred for initial staging. [68Ga]Ga-DOTA-TOC PET/CT findings affected patient management in 57% of cases with generally major intermodality changes. Intraindividual comparison of the results of the different PET radiopharmaceuticals showed a clear superiority of [68Ga]Ga-DOTA-TOC PET/CT considering both the number of lesions and the intensity of uptake. [68Ga]Ga-DOTA-TOC PET/CT is an accurate imaging modality for the assessment of well-differentiated colorectal NETs that highly impact patient management. Thus, we suggest that [68Ga]Ga-DOTA-TOC PET/CT be employed as a first choice for the assessment of these tumors in nuclear medicine.

The Clinicopathologic Features and Treatment of 607 Hindgut Neuroendocrine Tumor (NET) Patients at a Single Institution

The clinicopathologic features of hindgut neuroendocrine tumor (NET) as well as the treatment outcomes are not well known. There are currently no published data on treatment outcomes for patients with metastatic hindgut NET. The aim of this study was to conduct a comprehensive analysis of clinicopathologic features, treatments and survival in hindgut NET patients. Among patients who were pathologically diagnosed with hindgut NET at Samsung Medical Center between March 2001 and February 2015, 607 were analyzed in this study. Hindgut NETs were defined as NETs that originated from the transverse and distal colon, rectum, and anus. Primary sites included 81 colon (13.3%) and 526 rectum (86.7%). According to the WHO classification, 578 patients (95.2%) had grade 1 NETs, 17 (2.8%) grade 2 NETs, and 12 (2.0%) had neuroendocrine carcinoma (NEC). Forty-two patients (6.9%) had extensive disease, while the majority (93.1%, 565 patients) only exhibited localized disease. The 5- and 10-year survival rates of 565 localized NET patients were 98.1% and 95.3%, respectively. The median OS in 42 patients with extensive disease was 24.8 months (95% CI, 10.7-38.8). Among 565 patients with localized disease, the majority (484 patients, 85.7%) were treated with endoscopic procedure by gastroenterologists. For 42 patients with extensive disease, 17 patients were managed by supportive care, 3 by concurrent chemoradiotherapy (CCRT), and 22 by systemic therapy. Among these 22 patients, 12 patients received only first-line therapy, 8 had second-line, and only 2 patients had third-line therapy. As first-line chemotherapy, the most commonly used regimens were etoposide plus cisplatin (N = 7) and long acting octreotide (N = 7). During treatment courses, the most commonly used regimen was long-acting octreotide. The median OS in 22 metastatic NET patients receiving systemic therapy was 19.3 months (95% CI, 3.2-35.3). Multivariate analysis in all 607 hindgut NETs patients suggested that the extent and the primary site of disease were significant independent prognostic factors for long term survival. This analysis provides useful information about the clinicopathologic features, treatments and survival outcomes for hindgut NET patients.

Clinicopathological characteristics of rectal carcinoid patients undergoing surgical resection

The aim of this study was to clarify the clinical aspects, histopathological features and prognosis of patients with rectal carcinoids, focusing on properties associated with metastasis, in order to gain insights into appropriate management. A total of 20 patients (15 males, 5 females; mean age, 54.9 years; range, 23-71) who underwent surgery for rectal carcinoid tumors at the Department of Colorectal Surgery, Hyogo College of Medicine, between May 2000 and January 2011 were analyzed. Ki-67 immunostaining was performed in 13 cases with available tumor tissue specimens. Of the 20 patients, a radical operation including rectal resection with a lymphadenectomy was performed in 16. The mean tumor size was 11.9 mm (3-25 mm) and lymph node metastasis was confirmed in 9 cases, including 3 with lesions no greater than 7 mm in diameter. Overall, 16 (80%) of the tumors were localized in the submucosal layer and 4 (20%) involved the proper muscle layer. Ki-67 labeling index and lymphovascular invasion were shown to be associated with lymph node and/or distant metastasis by multiple logistic regression analysis, but were not statistically significant in ANOVA findings. Lymph node metastasis from rectal carcinoids, even those smaller than 10 mm in diameter, was not a rare event. More attention should be given to decision-making, including the possibility of endoscopic resection for the treatment of rectal carcinoid tumors regardless of size.

The NANETS consensus guidelines for the diagnosis and management of gastrointestinal neuroendocrine tumors (nets): well-differentiated nets of the distal colon and rectum

Neuroendocrine tumors (NETs) of the distal colon and rectum are also known as hindgut carcinoids based on their common embryologic derivation. Their annual incidence in the United States is rising, primarily as a result of increased incidental detection. Symptoms of rectal NETs include hematochezia, pain, and change in bowel habits. Most rectal NETs are small, submucosal in location, and associated with a very low malignant potential. Tumors larger than 2 cm or those invading the muscularis propria are associated with a significantly higher risk of metastatic spread. Colonic NETs proximal to the rectum are rarer and tend to behave more aggressively. The incidence of rectal NETs in African Americans and Asians is substantially higher than in Caucasians. Colorectal NETs are generally not associated with a hormonal syndrome such as flushing or diarrhea. A multidisciplinary approach is recommended in diagnosing and managing hindgut NETs.

Neuroendocrine tumors of the diffuse neuroendocrine system

PURPOSE OF REVIEW

Neuroendocrine tumors (previously referred to as carcinoids) are ill-understood, enigmatic malignancies that, although slow-growing compared with adenocarcinomas, can behave aggressively. In 2004, they comprised 1.25% of all malignancies; their incidence is increasing by approximately 6% per year. The present review provides an overview on neuroendocrine tumors and focuses on general features and current diagnostic and therapeutic options.

RECENT FINDINGS

Neuroendocrine tumors may present a considerable diagnostic and therapeutic challenge as their clinical presentation is nonspecific and usually late, when metastases are already evident. Topographic localization is by computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, whole-body positron emission tomography or endoscopy/ultrasound. Bronchoscopy is useful to verify the diagnosis when lesions are located centrally in the bronchi. No curative treatment except for radical surgery (almost never feasible) exists. Palliative and symptomatic treatment is based on surgical debulking, tumor embolization, and biotherapy with somatostatin analogues. Chemotherapy and radiotherapy are usually ineffective, but novel drugs such as tyrosine kinase receptor inhibitors show promising results in phase II clinical studies.

SUMMARY

Tumors of the diffuse neuroendocrine system represent a significant and increasing clinical problem, and there is a need to develop both early diagnostic tests as well as to establish targeted therapeutic strategies.