Brachytherapy in primary ocular tumors

Abstract

Patients with primary ocular tumors are seen infrequently in the medical profession, and most of these patients are referred to specialty centers which has resulted in a good study population. In the past, ocular tumors were treated with enucleation, but the current emphasis is now on organ preservation with sparing of all or partial visual acuity. In the management of these tumors, plaque brachytherapy and particle beam therapy have been used more frequently as an alternative to enucleation. A multi-institutional study, the Collaborative Ocular Melanoma Study (COMS), is currently underway, organized by the National Eye Institute. The COMS isotope of choice is Iodine-125 (I-125). Recurrence after plaque therapy is approximately 15%, although it may be as high as 37% at 15 years for metastatic disease. In one study, nondiffuse iris melanoma has been controlled in 93% of patients by custom plaques utilizing I-125. Plaque brachytherapy also utilizes I-125 for the treatment of retinoblastoma tumors either as primary therapy or following external beam radiation. Currently, through the utilization of plaque radiation therapy, enucleation may be avoided in the majority of patients, and many patients may retrieve some visual acuity. We will review plaque brachytherapy techniques, diagnosis, staging, and some of the pertinent literature of the two most frequently encountered primary ocular tumors: choroidal melanoma, sometimes referred to as uveal melanoma, with an incidence of approximately 1,500 new cases per year in the adult population; and retinoblastoma, the most common intraocular primary malignancy found in childhood, with a frequency of approximately 250 [corrected] new cases per year.