Inclusion Criteria:  1. Male or female patients 18 years of age or more 2. NEN confirmed by histology 3. Clinical, PET/CT or CT proven progression despite standard treatment with somatostatin analogues, targeted therapy (Everolimus, sunitinib), chemotherapy (STZ/5-FU, temozolomide/capecitabine) OR intolerable side effects caused by these standard treatment OR unmanageable carcinoid symptoms 4. WHO/ ECOG Performance Status of 0-2 5. Life expectancy more than 6 months 6. Uptake higher than liver in primary tumor or metastases on Ga-DOTATOC PET/CT (Krenning 3 or 4), if the scan is more than 3 months old at inclusion time, a new scan should be done. 7. Adequate organ function as defined by: Adequate kidney function: Patient glomerular filtration rate >30 ml/min measured by Tc-DTPA clearance  Adequate bone marrow function:  WBC ≥ 2.0 x 109/L Platelets ≥ 100 x 109/L Hb ≥ 6 mmol/l (≥9.67 g/dL)  8. Willingness and ability to comply with scheduled visits for SPECT/CT scans, treatment plans, laboratory tests and other study procedures.  9. Written informed consent obtained prior to any screening procedures  Exclusion Criteria:  1. Tumor amenable to surgery and/or radiofrequency ablation 2. Patients who are unable to stay isolated for 24 hours 3. Previous PRRT 4. Female patients who are pregnant or lactating. Women who are of childbearing potential (defined as all women physiologically capable of becoming pregnant) have to practice an effective method of contraception/birth control. Fertile female patients have to take a urinary pregnancy test, to ensure that they are not pregnant, before they can enter the study. After entering the study, they have to use effective contraception during the study period and 6 months after. Effective contraception methods include: Use of oral, injected or implanted hormonal methods of contraception or Placement of an intrauterine device (IUD) or intrauterine system (IUS) Total abstinence or patient sterilization (male or female) 5. Male patients are not allowed to conceive pregnancy for 6 months after last treatment cycle 6. Known to be hypersensitive to any component of the Lu-177-DOTATOC 7. Patients with meningioma