Fig. 3
The accuracy of th e c ombined prediction of a locoregional recurrence, b metastasis, and c overall survival in the validation cohort. In b, the curve of the relatively small medium risk group for metastasis is short; this is due to the short follow-up time until the metastasis occurred. A significant predictive risk stratification (p < 0.05) was shown, divided in low (0–33%), medium (33–66%), and high (66–100%) risk for an unfavorable prognosis