Stage IV includes: T0-4, Any N, M1. T0: No evidence of primary tumor. T1: Maximum clinical tumor diameter equal to or less than 2 cm. T2: Maximum clinical tumor diameter more than 2 cm but equal to or less than 5 cm. T3: Maximum clinical tumor diameter more than 5 cm. T4: Primary tumor invades fascia, muscle, cartilage, or bone. M1: Distant metastasis detected on clinical and/or radiologic examination. (AJCC 8th ed.) [from NCI]