Fig. 2

The optimal cut-off values for age (a-b) based on CSS were ≤ 58, 59–78, and ≥ 79 years old; (c-d) based on OS were ≤ 63, 64–79, and ≥ 80 years old. The optimal cut-off values for thin HNM (0–1.00 mm) (e-f) based on CSS were ≤ 0.6 and > 0.6 mm; (g-h) based on OS were < 0.6 and ≥ 0.6 mm. CSS = cancer-specific survival; OS = overall survival; HNM = head and neck melanoma