Purpose: Head and neck paragangliomas (HNPGLs) are rare tumours arising from autonomic nervous system ganglia. Although surgery offers the best chance of complete cure, there is associated morbidity due to the crucial location of these tumours. Radiotherapy arrests tumour growth and provides symptomatic improvement, but has long-term consequences. These tumours express somatostatin receptors (SSTR) and hence peptide receptor radionuclide therapy (PRRT) is now a treatment option. We assessed the molecular, morphological and clinical responses of inoperable HNPGLs to PRRT.
Methods: Nine patients with inoperable HNPGL assessed between June 2006 and June 2014 were included. Four patients had a solitary lesion, four had multifocal involvement and one had distant metastases (bone and lungs). The patients were treated with PRRT using (90)Y/(177)Lu-labelled peptides after positive confirmation of SSTR expression on (68)Ga-DOTATOC PET/CT. All patients received two to four courses of PRRT. Subsequent serial imaging with (68)Ga-DOTATOC PET/CT was carried out every 6 months to assess response to treatment. Clinical (symptomatic) response was also assessed.
Results: Based on molecular response (EORTC) criteria, four of the nine patients showed a partial molecular response to treatment seen as significant decreases in SUVmax, accompanied by a reduction in tumour size. Five patients showed stable disease on both molecular and morphological criteria. Six out of nine patients were symptomatic at presentation with manifestations of cranial nerve involvement, bone destruction at the primary site and metastatic bone pain. Molecular responses were correlated with symptomatic improvement in four out of these six patients; while two patients showed small reductions in tumour size and SUVmax. The three asymptomatic patients showed no new lesions or symptomatic worsening.
Conclusion: PRRT was effective in all patients, with no disease worsening seen, either in the form of neurological symptoms or distant spread. Though these are preliminary results, PRRT shows promise as a good treatment option for HNPGL, and hence study in a larger patient cohort is essential to establish its place in the management algorithm.