To assess the efficacy of various diagnostic modalities in detecting occult primary tumor location.
Retrospective medical record study.
Academic head and neck oncology practice.
A total of 183 consecutive patients with metastatic carcinoma of the neck from an unknown primary tumor during a 10-year period, after exclusion of those with previous history of head and neck cancer, a primary tumor site evident on physical examination, or primary tumors of the neck.
Main Outcome Measures
Identification of primary tumor location by various imaging modalities and panendoscopy with directed biopsies.
Primary tumor location was identified in 84 patients (45.9%). Preoperative imaging (computed tomography [CT], magnetic resonance imaging, positron emission tomography [PET], and/or PET-CT fusion scan) identified sites suggestive of primary tumor location in 69 patients. Subsequent directed biopsy of these sites yielded positive results in 42 cases (60.9%). The rate of successful identification of a primary tumor for each of the imaging modalities was as follows: CT scan of the neck, 14 of 146 patients (9.6%); magnetic resonance imaging of the neck, 0 of 13 patients (0%); whole-body PET scan, 6 of 41 patients (14.6%); and PET-CT fusion study, 23 of 52 patients (44.2%) (P = .001). The highest yield in identifying primary tumor sites was obtained in patients who had undergone PET-CT plus panendoscopy with directed biopsies with or without tonsillectomy: 31 of 52 patients (59.6%).
Diagnostic workup including PET-CT, alongside panendoscopy with directed biopsies including bilateral tonsillectomy, offers the greatest likelihood of successfully identifying occult primary tumor location.