Palladium-103 plaque radiotherapy for choroidal melanoma - Results of a 7-year study

Objective: To describe the first clinical experience with palladium-103 (Pd-103) ophthalmic plaque radiotherapy for choroidal melanoma. Design: Phase-I (nonrandomized) clinical trial. Participants: Eighty patients with uveal melanomas were diagnosed by clinical examination, found to be negative for metastatic disease, and offered Pd-103 radioactive plaque treatment. Nine patients were concurrently treated with microwave hyperthermia. Intervention: Palladium-103 ophthalmic plaque radiotherapy was employed for each patient. Eye plaques were sewn to the episclera to cover the base of the intraocular tumor, radiation was continuously delivered over 5 to 7 days, and then the plaques were removed. A mean apical dose of 81 Gy was delivered. Main Outcome Measures: The authors evaluated the ease of use of 103Pd seeds within standard gold eye plaques. Patient-related outcomes were control of tumor growth, change in visual acuity, the development of radiation damage (retinopathy, optic neuropathy, and cataract), and metastatic disease. Results: From September 1990 to December 1997, 80 patients were treated with Pd-103 and followed for an average of 38 months. Two patients were lost to follow-up. During this time, the authors found that Pd-103 seeds were equivalent to iodine-125 (I-125) with respect to plaque manufacture and ease of dosimetric calculations. Two patients in this series were treated for tumor recurrence after I-125 plaque radiotherapy. They both failed secondary Pd treatment and were enucleated. When Pd-103 was used as a primary treatment, it controlled the growth of 75 of 78 tumors (96%), Overall, there have been six enucleations: three failures of primary treatment, two failures of retreatment, and one for neovascular glaucoma. Visual acuity evaluations at the 36-month follow-up visit (including the enucleated patients) revealed that 38% of eyes had decreased 3 or more lines of vision, and 77% were 20/200 or better. Conclusion: Palladium-103 plaque radiotherapy can be used to treat uveal melanomas. Compared with I-125, computerized dosimetry suggests a more favorable dose distribution with Pd-103. Treatment of most patients resulted in tumor shrinkage and preservation of functional vision. The authors have noted no complications that might preclude the use of Pd-103 ophthalmic plaque radiotherapy for choroidal melanoma.