Clinical utility of PET/CT in the evaluation of head and neck squamous cell carcinoma with an unknown primary: a prospective clinical trial.

BACKGROUND: Metastatic head and neck squamous cell carcinoma with an unknown primary is an uncommon but important problem. PET/CT, as an adjunct to diagnosis, is potentially useful but has never been studied in a prospective, single-blinded clinical trial.

METHODS: In all, 20 subjects with cervical metastases from an unknown head and neck primary were enrolled in a prospective clinical trial. A standard protocol was used in both clinic and operating room (OR). Study surgeons were blinded to the PET/CT result upon completion of the standard work-up.

RESULTS: PET/CT increased the detection of a primary site from 25% to 55% (5 vs 11 subjects). This difference was statistically and clinically significant (p = .03, McNemar's test). There was 1 false negative PET/CT scan.

CONCLUSIONS: An unknown primary should be diagnosed only after a complete head and neck examination, flexible endoscopy, and CT or MRI. PET/CT performed prior to panendoscopy will increase the diagnostic yield in the unknown head and neck primary population, leading to more targeted, and less morbid, treatment.