Maximum Standardized Uptake Value (SUV(max)) of Primary Tumor Predicts Occult Neck Metastasis in Oral Cancer

The aim of this study was to investigate the predictability of occult lymph node metastasis using maximum standardized uptake value (SUV(max)) in the primary tumor on pre-treatment 18-fluorodeoxyglucose positron emission tomography FDG-PET in oral squamous cell carcinoma (OSCC) patients who were clinically node negative (cN0) before surgery. A retrospective analysis of all patients treated at the University Hospital Zurich from 2007 to 2016 for OSCC with available pre-therapeutic FDG-PET was performed. We assessed the correlation of SUV(max) of the primary tumors with the presence of occult nodal disease in the neck dissection specimen (pN+). The study included a total of 71 patients. In the nodal negative group (cN0/pN0), the median SUV(max) of primary tumors was 9.0 (interquartile range (IQR) 7.4–13.9), while it was 11.4 (IQR 9.9–15.7) in the occult metastatic group (cN0/pN+). The difference was statistically significant (independent samples median test, P = 0.037). In a multivariable model, the only independent predictor of occult metastatic disease for cN0 patients was a SUV(max) ≥ 9.5 (P = 0.028). Further, primary tumors with SUV(max) ≥ 9.5 had a significantly higher risk of local recurrence (Log rank test, P = 0.020). In conclusion, we showed that higher SUV(max) (≥9.5) of the primary tumor is associated with higher occurrence of occult metastatic nodal disease and worse local survival. High SUV(max) of the primary tumor may encourage clinicians towards more aggressive treatment.