Stage I includes: pT1, pT2, pT3, pN0, cM0, Any H. pT1: Intraocular tumor(s) without any local invasion, focal choroidal invasion, or pre-or intralaminar involvement of the optic nerve head. pT2: Intraocular tumor(s) with local invasion. pT3: Intraocular tumor(s) with significant local invasion. pN0: No lymph node involvement. cM0: No signs or symptoms of intracranial or distant metastasis. HX: Unknown or insufficient evidence of a constitutional RB1 gene mutation. H0: Normal RB1 alleles in blood tested with demonstrated high-sensitivity assays. H1: Bilateral retinoblastoma, retinoblastoma with an intracranial primitive neuroectodermal tumor (i.e., trilateral retinoblastoma), patient with family history of retinoblastoma, or molecular definition of a constitutional RB1 gene mutation. (AJCC 8th ed.) [from NCI]