Incidence and predictive factors of retropharyngeal lymph node metastases in patients with oropharyngeal cancer undergoing multimodality treatment planning imaging

Background We investigated the incidence and predictive factors of retropharyngeal lymph node (RPLN) metastases in patients with oropharyngeal cancer (OPC) undergoing multimodality treatment planning imaging before radiotherapy. Methods Consecutive patients with OPC treated with curative‐intent radiotherapy from 2017 to 2019 were retrospectively analyzed. Treatment planning comprised contrast‐enhanced computed tomography (CT), magnetic resonance imaging (MRI), and fluorodeoxyglucose‐positron emission tomography (FDG‐PET) unless contraindicated. Results Of 300 patients, 66 (22%) had radiological evidence of RPLN involvement on planning images, compared to 17 (6%) on diagnostic CT alone. On multivariate analysis, RPLN involvement was statistically (p