Prognostic significance of metabolic tumour volume and maximum standard uptake value of fluor-18-fluorodeoxyglucose positron emission tomography with computed tomography in nasopharyngeal carcinoma

Introduction
To evaluate the prognostic role of markers of fluor-18-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG-PET-CT), such as maximum standard uptake value (SUVmax) and metabolic tumour volume (MTV) measured at primary and nodal disease, and their clinical significance in terms of predicting treatment outcomes and survival.

Material and methods
Between January 2017 and January 2020, 20 case records of nasopharyngeal carcinoma patients who underwent 18F-FDG-PET-CT as part of staging workup before radiotherapy and as a part of response evaluation after radiotherapy were retrospectively reviewed.

Results
At a median follow-up of 34.7 months, the 2-year progression-free survival (PFS) was 70% and 2-year overall survival (OS) was 79%. Patients with a lower nodal SUVmax (SUVmax-N) had a better 2-year PFS (91% vs. 46%; p = 0.035) and 2-year OS (95% vs. 58%; p = 0.015). A high SUVmax-N of > 10.58 was a negative predictor of OS (95% confidence interval [CI]: 0.93–1; p = 0.003) as well as PFS (95% CI: 0.64–1; p = 0.017). Also, a high MTV > 25.8 cm3 was a negative predictor of PFS (95% CI: 0.58–0.98; p = 0.048). MTV was an independent predictor of PFS and OS on univariate analysis, whereas it was not significant in the Cox regression multivariate analysis.

Conclusions
High values of MTV and SUVmax-N can be considered as independent prognostic factors of OS and PFS in nasopharyngeal cancer patients treated with concurrent chemoradiation, highlighting the need for more intensified treatment.