An Update on Appendiceal Neuroendocrine Tumors

Area of Science:

• Gastroenterology
• Surgical Oncology
• Endocrinology

Background:

• Appendiceal neuroendocrine neoplasms (aNENs) are primarily treated with surgery, typically simple appendectomy or right-sided hemicolectomy with lymphadenectomy (RHC).
• Current guidelines inadequately stratify patients needing RHC, particularly those with aNENs measuring 1-2 cm.
• While appendectomy suffices for smaller tumors (<1 cm) with clear margins, larger or higher-grade tumors pose management challenges.

Purpose of the Study:

• To evaluate the current treatment strategies for appendiceal neuroendocrine neoplasms (aNENs).
• To identify limitations in existing guidelines for surgical management, especially for intermediate-sized tumors.
• To propose refined criteria for determining the extent of surgery, including RHC, for aNENs.

Main Methods:

• Review of current treatment guidelines and clinical practices for appendiceal neuroendocrine neoplasms (aNENs).
• Analysis of tumor size, grade, and lympho-vascular invasion in relation to metastatic potential.
• Emphasis on multidisciplinary tumor board (MTB) discussion for complex cases.

Main Results:

• Simple appendectomy is curative for aNENs <1 cm (G1-G2, R0 resection).
• Right-sided hemicolectomy (RHC) with lymphadenectomy is recommended for tumors ≥2 cm due to high nodal metastasis risk.
• Management of aNENs 1-2 cm is controversial; RHC is suggested for tumors >15 mm, G2, or with lympho-vascular invasion.

Conclusions:

• Treatment decisions for appendiceal neuroendocrine neoplasms (aNENs) require refinement beyond current guidelines, especially for 1-2 cm tumors.
• Tumor size >15 mm, G2 grade, or lympho-vascular invasion warrant consideration for RHC.
• Tailored treatment strategies, decided in multidisciplinary tumor boards, are crucial for optimizing patient outcomes.