Stage IV includes: (Any T, N1, M0); (Any T, Any N, M1a-c). N1: Regional lymph node metastasis or discrete tumor deposits in the orbit. M0: No distant metastasis. M1a: Distant metastasis, with the largest diameter of the largest metastasis measuring 3 cm or less. M1b: Distant metastasis, with the largest diameter of the largest metastasis measuring 3.1-8.0 cm. M1c: Distant metastasis, with the largest diameter of the largest metastasis measuring 8.1 cm or more. (AJCC 8th ed.) [from NCI]