Stereotactic Body Radiation Therapy followed by Peptide Receptor Radionuclide Therapy for the Treatment of Unresectable, Well-Differentiated Grade 1-2 Digestive System Neuroendocrine Tumors

Inclusion Criteria

• Male or female
• Age ≥ 18 years
• Patient must be able to provide study specific informed consent
• Pathologically confirmed neuroendocrine tumor fulfilling all of the following criteria
• Well-differentiated, grade 1-2
• Unresectable (prior resection is allowable), verified by tumor board or surgical oncology (surg onc)
• Progression after one or two prior lines of systemic therapy
• Somatostatin-receptor positive disease as determined by positive radiotracer-labeled DOTATATE PET/CT scan (modified Krenning score 3+)
• One or more large lesions measuring 3 or more cm on contrast-enhanced CT or MRI
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2
• Estimated glomerular filtration rate (GFR) > 30 mL/min (within 90 days prior to study registration)
• Total bilirubin ≤ 3 x upper limit of normal (within 90 days prior to study registration)
• Albumin > 30 g/L (within 90 days prior to study registration)
• White blood cell (WBC) ≥ 2,000 cells/mm^3 (within 90 days prior to study registration)
• Platelets ≥ 70000 cells/mm^3 (within 90 days prior to study registration)
• Hemoglobin ≥ 8.0 g/dl (Note: The use of transfusion or other intervention to achieve hemoglobin [Hgb] ≥ 8.0 g/dl is acceptable.) (within 90 days prior to study registration)

Exclusion Criteria

• Any prior radiation therapy including prior PRRT, external radiation, or Yttrium-90 radioembolization to the same site/region
• Contraindications to radiation therapy including inflammatory bowel disease, systemic sclerosis, etc.
• Brain metastases or any metastases extending into the spinal canal
• Unable to obtain confirmation of payment coverage for any planned radiation treatment