68Ga-DOTA0-Tyr3-octreotide positron emission tomography in head and neck squamous cell carcinoma

Abstract

⁶⁸Ga-labelled DOTA⁰-Tyr³-octreotide positron emission tomography (PET)/CT (⁶⁸Ga-DOTATOC PET/CT) is a routinely used imaging modality for neuroendocrine tumours expressing somatostatin receptors (SSTRs). Recent studies have shown that SSTRs are also expressed in head and neck squamous cell carcinoma (HNSCC). This is the first prospective clinical trial investigating SSTR expression in patients with HNSCC using ⁶⁸Ga-DOTATOC. Patients with previously untreated HNSCC underwent ⁶⁸Ga-DOTATOC PET/CT (120 MBq, range 81-150 MBq). Tumour tracer uptake was scored, the maximum standardized uptake value (SUVmax) was measured and the tumour to background uptake ratio was calculated. For each patient, PET/CT findings were correlated with immunohistochemical SSTR expression in tumour specimens. Fifteen HNSCC patients were included in the study from May 2011 to May 2012. Tumour-specific ⁶⁸Ga-DOTATOC uptake was detected in all patients with an median SUVmax of 4.0 (range 2.2-6.5). Uptake was weak in seven (47%), moderate in five (33%) and strong in three (20%) patients. All tumour specimens were SSTR positive on immunohistochemistry. Of the 15 patients, 14 were positive for SSTR subtype 2, characterized by the highest affinity to octreotide. SSTR expression in HNSCC can be visualized clinically using ⁶⁸Ga-DOTATOC PET/CT. SSTR expression in HNSCC could provide a potential target for SSTR-based therapy in patients not amenable to standard treatment modalities, but this cannot be predicted by SSTR immunohistochemistry.