8. Management of High-Risk Retinoblastoma

Invasion to the choroid, the sclera, and the optic nerve all constitute risk factors for extraocular relapse detected in enucleated eyes with retinoblastoma. Specifically, different degrees of invasion to these structures are associated with different risk and adjuvant therapy is tailored according to their presence. The relapse risk of children with isolated choroidal invasion is lower than 6 %, even in the higher risk subgroups with massive invasion and up to two thirds of those who relapse may be retrieved with intensive therapy. Hence, some groups use adjuvant therapy to further reduce the rate of extraocular relapse, while others do not give any treatment after enucleation. Most groups use adjuvant chemotherapy for children with postlaminar optic nerve invasion, but those with minor degrees of invasion may not need it. Since the relapse rate of these patients is low, the decision to use adjuvant therapy should be balanced in each setting with the possibility of fatal toxicities associated to chemotherapy.

Most groups use adjuvant therapy for those with scleral invasion and those with tumor at the resection margin of the optic nerve and more intensive regimens or orbital radiotherapy are recommended. Relapse in the central nervous system is the most common site for extraocular relapse in children receiving adjuvant therapy and it may become a sanctuary site when lower doses or drugs with low penetration to the cerebrospinal fluid are used. Molecular studies to determine the kinetics of minimal disease dissemination may provide more information.