Combination External Radiation and PRRT for Large GI Neuroendocrine Tumors.

This phase I trial tests the safety and effectiveness of stereotactic body radiation therapy (SBRT) followed by 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in treating patients with large well-differentiated grade 1-2 digestive system neuroendocrine tumors that cannot be removed by surgery (unresectable). SBRT is a type of external radiation therapy that uses special equipment to position a patient and precisely deliver radiation to tumors in the body. The total dose of radiation is divided into smaller doses given over several days. This type of radiation therapy helps spare normal tissue. 177Lu-DOTATATE is a radioactive drug. It binds to a protein called somatostatin receptor, which is found on some neuroendocrine tumor cells. 177Lu-DOTATATE builds up in these cells and gives off radiation that may kill them. It is a type of radioconjugate and a type of somatostatin analog. Giving PRRT after SBRT may reduce the chances of the disease returning or getting worse, compared to the standard treatment of PRRT alone.