Treatment of metastatic tumors of the choroid with proton beam irradiation

Abstract

To describe the clinical outcomes of patients treated by proton beam irradiation for choroidal metastatic tumors. Noncomparative case series. A retrospective chart review was performed on a series of 63 patients (76 eyes) with choroidal metastases treated with proton beam therapy between December 1989 and September 2000. Patients were treated with 2 fractions of 14 cobalt gray equivalents (CGEs) (CGE = proton Gy x relative biological effectiveness 1.1), each using a nonoperative "light-field" technique. Ophthalmologic follow-up was available for 46 patients (55 eyes), with a mean follow-up time of 10 months. The medical record or the Social Security Death Index was used to obtain survival status, which was available in 94% of cases. Tumor regression, recurrence, treatment-associated complications, and visual acuity were evaluated by ophthalmologic examination and ultrasonography. Eye retention and length of survival also were assessed. At the time of ocular diagnosis, 49 patients reported a history of a primary cancer. Median survival time after ocular diagnosis was 16 months through May 2003. Most choroidal metastases were dome shaped (62%) and located at the posterior pole (95%). Mean tumor height was approximately 3.5 mm, and serous retinal detachment was seen in 63% of cases. Eighty-four percent of treated tumors regressed completely within 5 months of treatment, and none of these recurred. Retinal detachment resolved in 82% of patients within 3.8 months after treatment, and visual acuity was preserved or improved in 47% of the patients. Complications occurred in 56% of cases and included madarosis, keratitis, dry eye syndrome, cataract, neovascular glaucoma, chorioretinal atrophy, radiation papillopathy, and radiation maculopathy. None of the treated eyes required enucleation. Proton beam irradiation is a useful therapeutic approach for choroidal metastases; it allows retention of the globe, achieves a high probability of local tumor control, and helps to avoid pain and visual loss. Although complications occur in most cases, many of these are minor and are not associated with a change in function. This modality is accurate and efficient, because it only entails 2 treatment fractions and does not require surgery for tumor localization.