Neuroendocrine Tumors

These heterogeneous neoplasms occur most in the gastrointestinal tract (65%), pancreas, and lungs, classified by grade: well-differentiated NETs (G1/G2, indolent) versus poorly differentiated NECs (G3, aggressive) based on Ki-67 index and mitotic rate. They feature uniform "salt-and-pepper" nuclei, secretory granules, and markers like synaptophysin/chromogranin.?

Symptoms and Diagnosis

Many are asymptomatic until advanced, but functional NETs trigger carcinoid syndrome (flushing, diarrhea from serotonin), Cushing's, or hypoglycemia; imaging (CT/MRI, octreotide scan), biopsy, and biomarkers (chromogranin A) confirm. Staging uses ENETS/TNM systems evaluating size, invasion, nodes, metastases.?

Treatment Options

Curative resection suits localized disease; for metastatic, somatostatin analogs (octreotide), PRRT (lutetium-177), chemotherapy (for NECs), or everolimus control progression; 5-year survival exceeds 90% for G1 GI-NETs but drops for high-grade. Multidisciplinary care optimizes outcomes.