1996 Jules Gonin Lecture of the Retina Research Foundation. Long-term results after proton irradiation of uveal melanomas.

Abstract

Melanoma of the uveal tract is the only life-threatening tumor in the adult. Over the past three decades, definitive radiotherapy, which spares the eye and preserves vision, has gradually replaced enucleation as the preferred treatment for these tumors. Two major techniques are available. One involves surgical placement of radioactive plaques on the sclera over the area of the tumor (brachytherapy) [l-3]. The second involves external beam irradiation with charged particles such as protons [4] and helium ions [5]. The latter approach, introduced in 1975 as a collaborative effort of the Massachusetts Eye and Ear Infirmary (MEEI), the Massachusetts General Hospital, and the Harvard Cyclotron Laboratory [6], was expected to improve local control and reduce the complications of brachytherapy. Theoretical advantages of charged particle irradiation are based on the physical characteristics of protons and helium ions, which make possible uniform and highly localized dose distributions [7]. In particular, eyes with tumors close to critical structures such as the macula and optic nerve could be irradiated and still maintain visual potential, because the dose is sharply reduced outside the target volume [8]. Today, 12 proton beam facilities are used for the treatment of uveal melanomas in North America, Europe, South Africa, and Japan, and over 6000 patients have been treated worldwide. By the end of 1995, 2242 patients had been treated at Harvard, and in this paper we present long-term follow-up statistics for the earliest patients, all of whom were treated more than a decade ago. Although visual acuity continues to decline with extended followup, enucleations are uncommon, local control is well maintained, and annual metastasis rates remain low throughout the decade following irradiation.