SUV for predicting regional control in oropharyngeal cancer.

Purpose: To investigate the predictive value of pretherapeutic metabolic tumor imaging using 18-fluorodeoxyglucose positron emission tomography (FDG-PET) for regional response in oropharyngeal cancer patients undergoing primary (chemo)radiation.

Methods: Retrospective analysis of oropharyngeal cancer patients treated with primary (chemo)radiation at the University Hospital Zurich from 2010 to 2019 with available FDG-PET. The SUV of the largest lymph node metastases was recorded. Regional response was assessed using posttherapeutic FDG-PET at 12 weeks and regional recurrence-free survival.

Results: 95 patients with a mean age of 68.5 years (SD 10.3) were included. The median pretherapeutic nodal SUV was 8.3 (interquartile range 4.4-13.3). A pretherapeutic nodal SUV above 6 significantly predicted poorer regional recurrence-free survival (log-rank test, P = 0.009) in univariate analysis. However, in multivariate analysis SUV above 6 was not significant in predicting regional recurrence-free survival (Cox regression P = 0.189). Clinical N category showed a trend in which a more severe stage had a poorer regional survival (Cox regression P = 0.073).

Conclusion: The SUV of the largest lymph node metastasis seems to play a role in predicting regional response in oropharyngeal cancer patients, after stratifying for N category. More research is needed to investigate whether highly metabolically active disease is less likely to respond to chemoradiation.