Carcinoma of unknown primary in the head and neck: comparison between positron emission tomography (PET) and PET/CT.

BACKGROUND Comparison of the diagnostic validity of positron emission tomography (PET) alone with integrated PET and CT (PET/CT) in the search for occult primary tumors in patients with cancer of unknown primary (CUP) site in the head and neck. METHODS Thirty-nine consecutive patients with clinical CUP were investigated with PET and 38 patients with PET/CT. After initial diagnostic panendoscopy and histological confirmation of the cervical lymph node metastasis, either PET or PET/CT scanning was performed. RESULTS Integrated PET/CT had a significantly higher overall detection rate than dedicated PET alone (55.2% vs 30.8%; p = .039) and positive prediction rate (93.3% vs 46.1%; p = .01). CONCLUSION Integrated PET/CT showed to be superior to PET in the detection of the primary site of clinically occult tumors in CUP syndrome. However, a negative result should still be investigated further by means of panendoscopy with tonsillectomy and blind biopsies.