Fig. 4.

Risk model estimating probability of recurrence of early oral tongue squamous cell carcinoma based on distance to closest margin and perineural invasion. Curve for estimating locoregional recurrence are shown. The

source paper illustrates curves for local recurrence, too. Model-derived estimated probability of 3-year locoregional recurrence-free survival is plotted against the distance to closest margin and perineural invasion status. The presented curve functions like a nomogram. For instance, a patient with a closest margin of about 1 mm and positive for perineural invasion would have an estimated probability of 3-year locoregional recurrence free survival of about 0.7 (probability of recurrence at 30%). Arrows illustrate how referencing for individual patients can be done. A black vertical arrow is drawn from the point corresponding to the distance to closest margin on axis “x” until the line crosses the orange Kaplan–Meier curve (with PNI). From this point on Kaplan–Meier curve, horizontal black arrow towards the “y” axis will point out the estimated probability of 3-year locoregional recurrence free survival