Neuroendocrine neoplasm update: toward universal nomenclature

Area of Science:

• Oncology
• Pathology
• Endocrinology

Background:

• Neuroendocrine neoplasia (NEN) occurs in various tissues, leading to diverse nomenclature across anatomical sites.
• Discrepant definitions cause confusion and non-standard patient management.
• The International Agency for Research on Cancer - World Health Organization (IARC-WHO) proposed a universal classification framework.

Purpose of the Study:

• To establish a uniform nomenclature for neuroendocrine neoplasia across all organs.
• To differentiate between well-differentiated neuroendocrine tumors (NET) and poorly differentiated neuroendocrine carcinoma (NEC).
• To propose a universal grading tool for predicting patient outcomes.

Main Methods:

• Review of evidence on neuroendocrine neoplasia phenotype and classification.
• Proposal of a standardized terminology: neuroendocrine neoplasm, neuroendocrine tumor (NET), and neuroendocrine carcinoma (NEC).
• Recommendation for a universal grading system based on proliferation markers (mitotic count, Ki67) and necrosis.

Main Results:

• Neuroendocrine neoplasia is characterized by a distinctive phenotype with specific markers.
• A proposed universal classification distinguishes NET (well-differentiated) from NEC (poorly differentiated).
• A grading tool using proliferation and necrosis is proposed for universal application with site-specific cut-offs.

Conclusions:

• The IARC-WHO framework aims to standardize neuroendocrine neoplasia nomenclature globally.
• This standardization is expected to improve patient management and facilitate site-specific gene signature research.
• Consistent classification and grading are crucial for understanding and treating neuroendocrine neoplasms.