Neuroendocrine Tumors Follow Up

Monitoring

Neuroendocrine tumors are slow growing but they may progress faster if they are poorly differentiated or have a high Ki67 index ≥5%. Patients should be monitored more closely during the first year after diagnosis to determine the status of the disease. Assess clinical manifestations, biomarkers, the presence of new sites of disease and quality of life during treatment. Routine evaluations, such as echocardiograms for patients with elevated 5-HIAA, to detect carcinoid heart disease in its early stages can improve prognosis. SSTR-based imaging or 18F-fluorodeoxyglucose-PET/CT scans (for high-grade tumors) are not advised for routine surveillance after definitive resection.  

Low-risk patients (eg carcinoid tumor of the appendix) usually require no follow-up. Low-risk patients are those having <2 cm primary tumor (<1 cm for rectal tumors), no nodal involvement and have low Ki67 <5%. Surveillance in patients with tumors of the appendix ≥1 cm to ≤2 cm every 2-5 years based on clinicopathological features is optional. For completely resected small (<1 cm) rectal tumors with negative margins, no additional follow-up is required. A repeat rectal MRI or endoscopic ultrasound 6-12 months after initial treatment is recommended for rectal NETs 1-≤2 cm in size.  

For gastrointestinal, pancreatic, lung and thymus NETs, surveillance at 12 weeks to 12 months post-resection includes:

• History taking and physical examination
• Measurement of appropriate biomarkers (gastrin, CgA and 5-HIAA) for functional tumors
• Multiphasic abdomen with or without pelvis CT or MRI for primary gastrointestinal and pancreatic NETs, and as clinically indicated for lung and thymic NETs
• Chest/abdomen CT with contrast for primary lung/thymic NETs, and as clinically indicated for primary gastrointestinal tumors
• Surveillance may be done every 1-2 years after the first year and as clinically indicated after 10 years

For patients with type 1 gastric NETs, follow-up endoscopies are recommended every 2 to 3 years or as clinically indicated and may also be considered in patients with type 2 gastric NETs. Imaging should also be performed if indicated.