Neuroendocrine tumor classification systems: Staging

Abstract

Staging of NETs classifies patients into prognostic groups.WHO has proposed a scientific and clinically related system for staging of NETs to respond to the current view that NETs are potentially malignant and consequently should be staged according to a site-specific cancer staging system (TNM). The most recent WHO classification separately grades and stages the tumors and applies to all gastroenteropancreatic NETs and also NETs arising throughout the body based on the organ of origin (including the thyroid, adrenal gland, and endocrine pancreas). Other widely used and accepted TNM staging systems for NETs are the one proposed by the American Joint Committee on Cancer (AJCC) and European Neuroendocrine Tumor Society (ENETS). Both systems are site specific. The system proposed by AJCC includes NETs of all anatomic sites whereas ENETS recommendations are limited to the TNM staging of gastroenteropancreatic NETs. The North American Neuroendocrine Tumor Society (NANETS) Consensus Guidelines for the Diagnosis of Neuroendocrine Tumor proposes the following goals for the initial tumor staging: “identification of primary tumor, assessment of extent of disease, and treatment planning.“NETs spread equally via blood or lymphatic system and the most common metastatic sites for GEP-NETs are the lymph nodes, liver, lung, peritoneum, and pancreas. Imaging studies for NETs, including plain film of the chest, cross-sectional imaging (CT or MRI) of the abdomen and pelvis, and octreotide scintigraphy, are recommended early in the course of patient care for initial staging.