SUVmax 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 SUVmax 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 SUVmax was 8.3 (interquartile range 4.4-13.3). A pretherapeutic nodal SUVmax above 6 significantly predicted poorer regional recurrence-free survival (log-rank test, P = 0.009) in univariate analysis. However, in multivariate analysis SUVmax 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 SUVmax 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.