Stage IV includes: IVA (Any T, N0, M1a, Any G); IVB (Any T, N1, Any M, Any G); (Any T, Any N, M1b, Any G). N0: No regional lymph node metastasis. N1: Regional lymph node metastasis. M1a: Distant metastasis to lung. M1b: Metastasis to other distant sites. (AJCC 7th ed.) [from
NCI]