Pretreatment 18 F-FDG uptake heterogeneity can predict treatment outcome of carbon ion radiotherapy in patients with locally recurrent nasopharyngeal carcinoma

Objective Our study was to investigate the value of pretreatment 18 F-FDG uptake heterogeneity to predict the prognosis of patients with locally recurrent nasopharyngeal carcinoma (LRNPC) treated by carbon ion radiotherapy (CIRT). Methods Twenty-nine LRNPC patients who underwent whole-body 18 F-FDG PET/CT scanning before CIRT were enrolled. Heterogeneity index (HI)-based 18 F-FDG uptake, and the PET/CT traditional parameters, including SUVmax, MTV, and TLG were assessed. Receiver operator characteristics (ROC) determined the best cutoff value, and local recurrence-free survival (LRFS) and progression-free survival (PFS) were evaluated by the Kaplan–Meier method and log-rank test. And the predictive ability was evaluated by the ROC curve. Cox analyses were performed on LRFS and PFS. Results In this study, univariate analysis showed that HI was a significant predictor of LRNPC treated by CIRT. HI could be used to predict LRFS and PFS. Patients with HI (≥ 0.81) had a significantly worse prognosis of LRFS (12.25 vs. NR, p = 0.008), and of PFS (10.58 vs. NR, p = 0.014). The AUC and its sensitivity and sensitivity and specificity were 0.75, 84.21% and 70.00% for LRFS and 0.82, 80.95% and 75.00% for PFS, respectively. Multivariate analysis showed that HI was an independent predictor for the LFRS of LRNPC with CIRT. Conclusion 18 F-FDG uptake heterogeneity may be useful for predicting the prognosis of patients with LRNPC treated by CIRT.