Retinoblastoma: correlation of invasion of the optic nerve and choroid with prognosis and metastases.

The histological sections of 74 retinoblastoma patients were reviewed. The extent of optic nerve invasion was correlated with choroidal/scleral extension. Choroidal invasion carries 100% survival provided that the sclera, iris, and whole optic nerve are not also involved. Invasion of the optic nerve beyond the lamina cribrosa also carries 100% survival provided that the resection line is free and that invasion does not involve the sclera or iris. Plentiful rosettes were usually found in those tumours that had not extended beyond the choroid or as far as the resection line of the optic nerve and were therefore associated with a good prognosis. The absence of rosettes did not necessarily indicate a poor prognosis. The site of metastases was related to optic nerve and scleral/extrascleral extension. The various systems of staging retinoblastoma are compared, and a new system is proposed to cover the whole spectrum of the disease and to offer a reliable guide to prognosis and treatment.