FDG-PET Staging of Head and Neck Cancer—Can Improved Imaging Lead to Improved Treatment?

Head and neck cancer levies a steep toll from those it afflicts, particularly through treatment-associated toxicity. Tangible improvements in tissue sparing, supportive care, and recuperative strategies have been made. Nonetheless, combined modality strategies favored for locally advanced disease continue to demand substantial cosmetic, nutritional, and functional sacrifices in exchange for improved survival. The way to best limit such morbidity is to tailor treatment to the exact location and severity of disease. If the tumor can be reliably localized, bystander tissues appropriately excluded from operative and radiation fields, and lower risk patients safely triaged away from cytotoxic chemotherapy, then the up-front and longitudinal costs of head and neck cancer treatment can be tangibly reduced without conceding efficacy. In this spirit, 18 F-fl uorodeoxyglucose positron emission tomography (FDG-PET) imaging has gradually become part of the routine management of head and neck cancer over the past decade. FDG-PET has been touted to provide benefi t for a spectrum of indications, including up-front locoregional and whole-body staging, geographic delineation of tumor for radiotherapy planning or surgical neck management, detection of disease response to nonsurgical therapy (ie, chemotherapy, radiation, or chemoradiation), identifi cation of occult primary disease, and posttreatment surveillance and restaging. These claims have been made despite a conspicuous absence of supporting data from randomized studies. Results from cohort studies have supported many of these indications, and the sheer number of such reports certainly infl uenced the decision of Centers for Medicare and Medicaid Services (CMS) to approve reimbursement for FDG-PET imaging for diagnosis, staging, and posttreatment restaging of head and neck cancer ( 1 ). In this issue of the Journal, Kyzas et al. ( 2 ) present the fi rst formal meta-analysis available of institutional data documenting the ability of FDG-PET to accurately stage cervical neck nodal basins before locoregional treatment. The authors selected 32 retrospective and prospective studies from the international literature encompassing 1236 cases that could be analyzed in aggregate for diagnostic accuracy via confi rmatory neck dissection pathology. Two-thirds of these series enrolled mixed populations of clinically node-negative (N0) and node-positive patients, and seven specifi cally studied patients with clinically N0 necks. The vast majority of series (and all dated before 2005) used single-modality PET scanners rather than combined PET and computer tomography (PET/ CT). Analysis of this selected dataset demonstrated FDG-PET to be a sensitive (79%, 95% confi dence interval [CI] = 72% to 85%) and specifi c (86%, 95% CI = 83% to 89%) staging technique for this indication. In head-to-head comparisons with “competing” modalities, FDG-PET provided incremental, yet clinically meaningful improvements in neck staging accuracy. A notable exception to this rule was ultrasound-guided fi ne-needle aspiration, which not surprisingly, given that it is a mixed imaging-tissue diagnostic procedure most frequently performed by specialized diagnosticians at referral centers, appeared to outperform PET’s sensitivity. Another noteworthy fi nding was that FDG-PET could not improve detection of occult adenopathy in clinically N0 patients. This result confi rms the already commonly accepted notion that FDG-PET alone fails to offer clinicians suitable guidance to defer elective nodal dissection in the clinically N0 patient. One cannot single out PET for this shortcoming; 50% sensitivity is comparable to the higher range of what is reported for ultrasound-guided fi ne-needle aspiration or CT ( 3 , 4 ). At face value, the results of this meta-analysis formalize what the majority of head and neck FDG-PET imaging reports have suggested over the past decade. Yet, real-world benefi ts resulting from incremental neck staging improvement provided by FDG-PET remain in the eye of the beholder. Some concur with the interpretation of Kyzas et al. ( 2 ) of the literature that FDG-PET offers “added value” over other modalities ( 5 ). Others come to a less sanguine