Combination of panendoscopy and positron emission tomography/computed tomography increases detection of unknown primary head and neck carcinoma

Objectives/Hypothesis: With positron emission tomography/computed tomography (PET/CT) now commonplace as a diagnostic tool, new questions have arisen regarding the utility and cost-effectiveness of panendoscopy. In this retrospective review of a large cohort of head and neck squamous cell carcinoma of unknown primary (HNSCC-UP), we describe the enduring utility of panendoscopy in the detection of the primary site of mucosal disease even when PET/CT is negative. Study Design: Retrospective cohort study. Methods: A retrospective analysis of patients presenting to the senior author (y.d.) from July 1 1997 to July 1 2017 with fine-needle aspiration-proven metastatic squamous cell carcinoma to the neck. All patients underwent formal panendoscopy (direct laryngoscopy, bronchoscopy, and rigid esophagoscopy). Presence of squamous cell carcinoma on final pathology was examined. Results: A total of 190 patients had HNSCC-UP, with 87 positive and 103 negative on PET/CT. Of the PET/CT-negative patients, 71 patients retained the HNSCC-UP designation after panendoscopy. Eighteen patients (56% of cases) were found to have primary tonsillar squamous cell carcinoma. Eight of 32 primary sites were found in the base of tongue (25%), with HPV positivity in two of these patients. The sensitivity and negative predictive value of PET/CT in detecting the primary site in unknown primary head and neck squamous cell carcinoma in the total study population were 73.1% and 68.9%, respectively. Conclusions: Surgical panendoscopy has an important role in the workup of patients with unknown primary head and neck squamous cell carcinoma. There is a high rate of cancer diagnosis, even in PET/CT negative patients.