Endocrine Abstracts

Background: Paragangliomas are rare neuroendocrine tumours arising in the autonomic nervous system, which can secrete excess catecholamines, causing cardiovascular complications. Malignancy occurs in up to 23% of paragangliomas, resulting in a poor prognosis with a 5-year mortality of 43–63%. There’s a limited evidence base for their treatment, with no official guidelines. Peptide Receptor Radionuclide Therapy (PRRT) is a proven treatment for neuroendocrine tumours of the gastrointestinal tract and pancreas, through targeting somatostatin receptors on the tumour. Paragangliomas also highly express these receptors, so PRRT could be an effective treatment for them.

Aims: This study aims to examine outcomes of patients with metastatic/unresectable paragangliomas treated with PRRT, focussing on progression-free survival (PFS), tumour response and symptomatic improvement.

Methods: Patients diagnosed with metastatic/unresectable paragangliomas, underwent ⁶⁸Ga-DOTATATE PET/CT scans to assess DOTATATE uptake and had at least 1 cycle of PRRT. Data was collected for 6 patients being treated at Royal Marsden NHS Trust from 2012 to 2019. Changes in tumour size and patient symptoms were recorded, and PFS was calculated.

Results: 6 patients had a median PFS of 13 months. Using Response Evaluation Criteria In Solid Tumours (RECIST) to evaluate change in tumour size post-PRRT, 3 patients had a partial response, 2 had stable disease and 1 had progressive disease. Symptoms improved and Eastern Cooperative Oncology Group (ECOG) performance status remained the same, in 5 out of the 6 patients. 1 patient experienced mild toxicity from PRRT, and 1 patient’s condition deteriorated despite treatment.

Conclusions: The median PFS of our patients was lower than that recorded in literature, but our patients’ best response rates of tumours were much higher, and symptoms improved in as little as 3 months in most. Literature shows that PRRT confers a much greater survival than other treatments. Additionally, our patients had limited toxicity to PRRT, so our series increases the evidence base of PRRT for treating metastatic/unresectable paragangliomas.