Changes in categorization or nomenclature within neuroendocrine tumors

Area of Science:

• Oncology
• Pathology
• Endocrinology

Background:

• The World Health Organization (WHO) classification of neuroendocrine neoplasms (NENs) requires updates to ensure uniform terminology and diagnostic schemes.
• Previous editions established foundational classifications, but advancements necessitate revisions for broader anatomical coverage and refined grading.
• The 4th edition introduced NENs in non-neuroendocrine organs, setting the stage for further integration and standardization.

Purpose of the Study:

• To present the key changes and advancements in the 5th edition of the WHO classification of neuroendocrine neoplasms.
• To highlight the adoption of a binary classification system (neuroendocrine tumors/carcinomas) and revised grading strategies.
• To emphasize the impact of the new classification on multidisciplinary diagnosis, clinical management, and future research directions.

Main Methods:

• Review and synthesis of the updated guidelines from the 5th edition of the WHO classification of neuroendocrine neoplasms.
• Analysis of the proposed binary classification system for well-differentiated (NETs) and poorly differentiated (NECs) neoplasms.
• Examination of the revised grading systems based on mitotic index, Ki-67, and necrosis, adapted for various anatomical locations.

Main Results:

• Introduction of a uniform terminology and diagnostic scheme for NENs across diverse anatomical locations.
• Implementation of a binary classification system (NETs vs. NECs) and location-specific grading criteria.
• Endorsement of the carcinoid/NET terminology for lung and thymus NENs, aligning with thoracic tumor classifications.

Conclusions:

• The 5th edition WHO classification promotes a standardized approach to NEN diagnosis and management, facilitating multidisciplinary collaboration.
• The revised classification accommodates site-specific characteristics while ensuring consistency, improving understanding of NEN behavior.
• This updated framework supports the integration of epidemiological data and molecular profiling for personalized therapeutic strategies.