Interim FDG PET/CT for predicting the outcome in patients with head and neck cancer

Objectives/Hypothesis The study aimed to investigate the prognostic effects of interim 18fluoro‐2‐deoxy‐D‐glucose positron emission tomography/computed tomography (PET/CT) during definitive radiotherapy (RT) or chemoradiotherapy (CRT) in patients with head and neck cancer. Study Design This is a prospectively treatment study. Methods The pretreatment and interim PET/CT images of 51 patients with advanced pharyngeal cancers receiving definitive RT/CRT were evaluated prospectively. The interim PET/CT images were taken at a cumulative RT dose ranging from 41.4 to 46.8 Gy. The maximum standardized uptake value (SUVm) of the interim PET/CT and the reduction ratio of the SUVm (SRR) between the two images were measured. The differences between patients with or without local failures were examined using the Mann‐Whitney test. Overall survival (OS), disease‐free survival (DFS), and primary and nodal relapse‐free survival rates were calculated using the Kaplan‐Meier method. Independent prognosticators were identified using Cox regression analysis. Results After a median follow‐up duration of 23 months, a higher interim SUVm was associated with local failures. Conducting a multivariate analysis revealed that a SUVmax reduction ratio of primary tumor (SRR‐P)