Stage I includes: (T0, N0, M0); (T0, N1, M0); (T1, N0, M0); (T1, N1, M0); (T2, N0, M0); (T2, N1, M0). T0: No primary identified. T1: Tumor 2 cm or smaller in greatest dimension. T2: Tumor larger than 2 cm but not larger than 4 cm in greatest dimension. N0: No regional lymph node metastasis. N1: Tumor with metastasis in four or fewer lymph nodes. M0: No distant metastasis. (AJCC 8th ed.) [from NCI]