This protocol provides guidelines for the management of non-metastatic unilateral retinoblastoma and introduces an innovative adjuvant therapy for higher risk patients based upon the results of the Grupo de America Latina de Oncologia Pediatrica (GALOP) I study. Conservative therapy will be not protocolized.

Patients with non-metastatic retinoblastoma undergoing enucleation will be staged using the American Joint Committee on Cancer (AJCC), version 8, Tumor, Node, Metastasis (TNM)- H system and the International Retinoblastoma Staging System (IRSS). IRSS stage I patients recognized as higher risk will be assigned for adjuvant therapy. Those with standard risk will not receive adjuvant therapy after enucleation. Higher risk patients are defined as those with pathological retrolaminar optic nerve invasion and-or any degree of scleral invasion (pT3b, pT3c, pT3d). Based on the results of the GALOP I protocol, they will receive a reduced dose adjuvant chemotherapy regimen with 3 cycles of alternating cyclophosphamide, vincristine and idarubicin alternating with another 3 cycles of carboplatin and etoposide. Six doses of intrathecal topotecan will be given. Patients presenting with severe buphthalmia (cT3c-cT3e) will receive neo-adjuvant therapy with the same intensive regimen but including a higher dose of carboplatin as per GALOP I protocol plus intrathecal topotecan and secondary enucleation followed by adjuvant chemotherapy for a total of 8 cycles. Stage II patients (pT4) will receive the same adjuvant regimen plus orbital radiotherapy (45 cGy).

Inclusion Criteria:

• Histological diagnosis of retinoblastoma confirmed at participating institutions
• Ophthalmological diagnosis of unilateral retinoblastoma in patients undergoing conservative therapy.
• No prior therapy for retinoblastoma
• Lansky Performance Scale greater or equal to 50
• Normal organ function in those patients assigned for chemotherapy
• Signed informed consent

Exclusion Criteria:

• Patients with unilateral retinoblastoma and germline mutations of the Rb1 gene or family history for retinoblastoma