Prognostic significance of hypermetabolic contralateral cervical lymph node in patients with oral and oropharyngeal squamous cell carcinoma

• There was no survival difference for patients with lateralized tumors with contralateral lymph nodes on the initial PET/CT compared to patients without contralateral hyperfixation. • The positive predictive value of a contralateral positive lymph node is 35% for lateralized tumors. • There is a risk of overtreatment in 65% of patients in cases of contralateral fixation and lateralized tumors. The nodal spreading of oral cavity and oropharynx squamous cell carcinoma (OCSCC/OSCC) remains a critical challenge. The pathological nature of lymph nodes adjacent to the tumor is sometimes difficult to interpret on PET/CT during the initial assessment. The primary objective of this study was to evaluate the impact of contralateral node PET/CT hyperfixation on disease-free survival (DFS) in lateralized OCSCC or OSCC. From our database, all patients who had a PET/CT during their management for a lateralized SCC were selected between 2018 and 2021. Clinical, histological and radiological data between patients with and without contralateral nodes on the initial PET/CT were compared, as well as the survival of these patients. The Inselspital, Bern University Hospital (ISB) publicly available dataset was then used, to estimate the positive predictive value (PPV) of a contralateral fixation. Of 48 patients who had a PET/CT for lateralized OCSCC or OSCC, 16 (33%) had contralateral lymph node hyperfixation on PET/CT (PET/CT CLN+). In this group, 4 had a bilateral lymph node dissection (27%), and only one had lymph node metastasis. Using the ISB dataset, we found a PPV of only 35% for these contralateral hyperfixation. There was no significant difference in a multivariate Cox model in terms of DFS between the two subgroups in the case of lateralized tumors. There was no difference in survival between patients with or without contralateral lymph nodes on the initial PET/CT.