Positron emission tomography in the management of unknown primary head and neck carcinoma

Objective: To assess the role of positron emission tomography (PET) in the management of unknown primary carcinoma of the head and neck region. Design and Setting: Prospective case series at an academic medical center. Patients: Twenty-six patients with an open excisional biopsy or a fine-needle aspiration biopsy finding that confirmed squamous cell carcinoma of the cervical lymph nodes and no visible primary tumor (as determined by results of a comprehensive physical examination and computed tomography and/or magnetic resonance imaging) underwent PET. The standard evaluation consisted of a comprehensive head and neck examination that included fiberoptic laryngoscopy/ nasopharyngoscopy, computed tomography and/or magnetic resonance imaging, and PET followed by panendoscopy with selected biopsies and tonsillectomy. Main Outcome Measures: Sensitivity, specificity, and positive and negative predictive values of PET to detect an occult primary tumor. Results: The PET detected 8 occult primary tumors in 26 patients (detection rate, 30.8%). Four occult primary tumors (2 at the base of the tongue and 2 in the tonsil) were detected during routine panendoscopy with negative PET findings. The sensitivity of PET was 66.0%, with a specificity of 92.9%. The positive predictive value was 88.8%, and the negative predictive value was 76.5%. Conclusions: Positron emission tomography can be a valuable tool to identify a subset of patients with an occult primary tumor in the head and neck region. In addition, it can be used to screen for primary tumors below the clavicle. Early identification of the primary tumor may allow for more accurate tumor staging and targeted radiotherapy to minimize adverse effects and complications. A normal PET finding, however, does not eliminate the need for a careful panendoscopy with directed biopsies and tonsillectomy.