Neuroendocrine Tumors (NETs): Types, Hormonal Syndromes, Diagnosis, and Multidisciplinary Treatment

Neuroendocrine tumors (NETs) arise from diffuse neuroendocrine cells, most often in the GI tract (carcinoid), pancreas, or lungs. They span a spectrum from indolent to aggressive.

Common Symptoms (Often Hormone-Mediated)

• Carcinoid Syndrome: Flushing, diarrhea, wheezing, valvular heart disease (serotonin-driven).
• Functional Pancreatic NETs: Insulinoma (hypoglycemia), gastrinoma (ulcers/ZES), glucagonoma (rash, diabetes), VIPoma (watery diarrhea).
• Non-Functional: Mass effect—pain, obstruction, bleeding.
• General: Fatigue, weight loss, abdominal discomfort.

Diagnosis

• Biochemical: Chromogranin A, 5-HIAA (urine), specific hormone panels.
• Imaging: Ga-68 DOTATATE PET/CT (gold standard), MRI liver, CT chest/abdomen/pelvis.
• Biopsy: Ki-67 index critical for grading (G1 <3%, G2 3–20%, G3 >20%).

Treatment by Grade/Stage

• Localized G1/G2: Surgical resection (curative intent).
• Metastatic Well-Differentiated (G1/G2): Somatostatin analogs (octreotide/lanreotide) for symptom control + antiproliferative effect; PRRT (Lu-177-DOTATATE) for SSTR+ progression; everolimus, sunitinib (pancreatic NET); liver-directed therapies (embolization, ablation).
• Poorly Differentiated NEC (G3): Platinum-etoposide chemotherapy ± immunotherapy.

Key Principle

NETs require a dedicated multidisciplinary team (medical oncology, surgery, interventional radiology, nuclear medicine, pathology, genetics, nursing) for optimal sequencing and quality of life.