Prospective imaging assessment of mortality risk after head-and-neck radiotherapy.

PURPOSE: The optimal roles for imaging-based biomarkers in the management of head-and-neck cancer remain undefined. Unresolved questions include whether functional or anatomic imaging might improve mortality risk assessment for this disease. We addressed these issues in a prospective institutional trial. METHODS AND MATERIALS: Ninety-eight patients with locally advanced pharyngolaryngeal squamous cell cancer were enrolled. Each underwent pre- and post-chemoradiotherapy contrast-enhanced computed tomography (CT) and (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT imaging. Imaging parameters were correlated with survival outcomes.
RESULTS: Low post-radiation primary tumor FDG avidity correlated with improved survival on multivariate analysis; so too did complete primary tumor response by CT alone. Although both imaging modalities lacked sensitivity, each had high specificity and negative predictive value for disease-specific mortality risk assessment. Kaplan-Meier estimates confirmed that both CT and FDG-PET/CT stratify patients into distinct high- and low-probability survivorship groups on the basis of primary tumor response to radiotherapy. Subset analyses demonstrated that the prognostic value for each imaging modality was primarily derived from patients at high risk for local treatment failure (human papillomavirus [HPV]-negative disease, nonoropharyngeal primary disease, or tobacco use).
CONCLUSIONS: CT alone and FDG-PET/CT are potentially useful tools in head-and-neck cancer-specific mortality risk assessment after radiotherapy, particularly for selective use in cases of high-risk HPV-unrelated disease. Focus should be placed on corroboration and refinement of patient selection for imaging-based biomarkers in future studies.