Peptide Receptor Radionuclide Therapy (PRRT)

PRRT is mainly used for:

• Neuroendocrine tumours (NETs): Slow-growing tumours that arise from hormone-producing cells found throughout the body.
• Phaeochromocytoma and paraganglioma: Rare tumours that develop from adrenal or nerve-related cells and may produce excess hormones, causing high blood pressure.
• Neuroblastoma: A childhood cancer that starts in immature nerve cells, most often in the adrenal glands.
• Lung carcinoid: A rare type of lung cancer that usually grows slowly and arises from hormone-producing cells in the lungs.
• Medullary thyroid carcinoma: A cancer of the thyroid gland that starts in special C-cells, which produce the hormone calcitonin.
• Meningioma: A usually slow-growing tumour that develops from the protective membranes covering the brain and spinal cord. 

• After eligibility assessment and fitness evaluation, the following steps are involved:
• The PRRT medicine is administered slowly through an IV under the supervision of the Nuclear Medicine Physician with continuous monitoring of vital signs.
• Depending on the nature of the tumour, PRRT may be combined with somatostatin analogues or chemotherapy.
• The total time taken for the therapy administration ranges from 4 to 6 hours. 

• Each treatment session takes about 4–6 hours.
• Patients may be discharged the same day or the following day, depending on their condition.
• PRRT is usually given in 4–6 cycles, spaced 10–12 weeks apart.
• Following two cycles, response evaluation is done with DOTA PET scan (FDG PET CT if required). 
   

• Pre-therapy evaluation and eligibility assessment:
  • A DOTA PET-CT scan is performed to confirm receptor expression status on the targeted lesions. FDG PET-CT can also be combined in a specific setting.
  • Lab tests: CBC, serum creatinine, LFT, and RFT tests are done to confirm that the parameters are within the expected range.
  • ECOG/performance status is assessed for overall functional level.
  • Comorbidities evaluation is done to check for underlying diseases.
• Medications: On the day of the treatment, you may receive antiemetics or steroids and amino acid infusion to reduce renal toxicity.
• Hospital admission: The therapy is given only in nuclear medicine wards approved by the regional radiation regulatory body for safety.

• Short-term and common: Nausea and vomiting (managed by pre-therapeutic antiemetic medications)
• Rare but possible: Sudden hormone release causing crisis (carcinoid/catecholamine crisis), managed by proper pre-therapeutic evaluation, continuous monitoring of vitals, and antagonistic medications.
• Long-term:
  • Derangement of liver and kidney functions (monitored with regular blood tests).
  • Temporary drop in blood counts (RBC, WBC, and platelets); usually mild and recovers by the end of the month.   

• Radiation safety: PRRT uses very small amounts of radiation. Over the next several days, the radionuclide will leave the body through urine and faeces. Avoid close contact with children and pregnant women for a few days. No other specific precautions post-PRRT administrations are required.
• Back to normal life: Most patients can resume routine activities within a few days.
• Expected benefits:
  • Significant reduction of pain and hormone-related symptoms (flushing, diarrhoea, abdominal pain).
  • Tumour shrinkage on the PET CT scan or stability of the disease (stable disease is also considered a significant response as per international guidelines)
  • Improved quality of life and longer progression-free survival compared to conventional treatments.