177Lu-DOTATOC for the Treatment of Patients With Somatostatin Receptor Positive NETs

Inclusion Criteria: * Able to provide written informed consent * Age greater than or equal to 19 years * Biopsy-proven, well-differentiated grade 1 - 3 NET * Gastroenteropancreatic tumors (e.g. carcinoids, gastrinoma, insulinoma, glucagonoma, VIPoma, etc.), functioning and non-functioning * Sympathoadrenal system tumors (phaeochromocytoma, paraganglioma) * Pulmonary NET, functioning and non-functioning * Easter Cooperative Oncology Group (ECOG) ≤ 2 * Ki67 ≤ 55% * Progressive disease demonstrated by RECIST 1.1 criteria within the 6 months preceding the study. * Patients with other evidence of progressive disease that is not demonstrated on CT (like rising biomarkers) may be included, at the discretion of the Tumour Review Board. * If response to other treatments is considered adequate according to other criteria, the Tumour Review Board may consider excluding the patient from participation in the study. * Tumour Review Board confirmation of suitability to proceed to PRRT treatment and enrollment in this trial. * Positive PET SSR imaging (Krenning score 2 or higher) in previous 6 months (68Ga-DOTATOC, 68Ga-DOTATATE, 18F-AmBF3-TATE). If PET SSR imaging is not available 111In-penetreotide scintigraphy (Octreotide scan) is acceptable. * Adequate laboratory parameters within two weeks of enrollment * Kidneys * Serum creatinine ≤ 150 µmol/L * GFR ≥ 40 ml/min (using plasma clearance values) * Marrow * Hemoglobin ≥ 80 g/L * WBC ≥ 2 x 109/L * Platelets ≥ 75 x 109/L * Liver * Total bilirubin ≤ 3 x upper limit of normal (ULN) * ALT ≤ 3 x ULN or ≤ 5 x ULN if liver metastasis * Alkaline phosphatase ≤ 3 x ULN or ≤ 5 x ULN if liver metastasis * Subject's ability to comply with scheduled visits, treatment plans, laboratory tests, imaging tests, and other procedures required as detailed in the protocol. Exclusion Criteria: * Women and men of childbearing potential Procreation * Women: pregnancy test done before enrollment before each treatment cycle. And subject must use adequate contraception for the duration of therapy, be surgically sterile, or post-menopausal. * Men: must be surgically sterile or use adequate contraception for the duration of the therapy. * Patient with another non-cutaneous (excluding melanoma) active cancer requiring therapeutic intervention. * Curative medical or surgical treatment, local liver embolization, or debulking are appropriate options. * Life expectancy is less than 12 weeks. * Radiotherapy to target lesions ≤ 12 weeks ago or to more than 25% of bone marrow. * PRRT at any time prior to randomization in this study. * Systemic therapy (chemotherapy) within 4 weeks of PRRT and other locoregional therapies (radioisotope, embolization) within 12 weeks prior to enrollment. Ongoing use of somatostatin analogs for control of symptoms is allowed. * Known brain metastases (unless treated and stable for more than 3 months). * Co-morbidities that could, in the opinion of the PI, interfere with safe delivery of PRRT (like urinary incontinence, psychiatric illness), uncontrolled congestive heart failure (NYHA II, III, IV) * Breastfeeding (if patients elect to discontinue breast feeding, they can participate in the trial).