Episcleral plaque brachytherapy (EPB) has been used to treat intraocular (eye) tumors since the early 1900s. The two most common indications for EPB are ocular/choroidal melanoma and retinoblastoma. Local control is paramount, as failure to achieve this goal results in both local (vision loss, pain) and systemic (liver, lung, bone metastasis) consequences, including death. Prior to the 1980s, the treatment of choice was enucleation (eye removal) with the associated major downside of ipsilateral (side where the eye is removed) vision loss. EPB offers the possibility of both organ and vision preservation while controlling or eradicating the tumor.
The medium tumor Collaborative Ocular Melanoma Study (COMS) was a randomized study reflecting class 1 (considered the most reliable) evidence for effectiveness of EPB compared to enucleation. This multi-institutional trial enrolled more than 1,300 patients with medium-sized choroidal melanoma, and patients were randomized to either enucleation or Iodine-125 EPB. At the 12-year mean follow-up, there was no survival difference, including death from histopathologically (changes in tissue caused by disease) confirmed melanoma metastases. Eighty-seven percent of patients treated with EPB retained their eye at five years, with 43 percent of the treated eyes demonstrating visual acuity of 20/200 or worse at three years.
Required information from the ophthalmologist includes eye laterality (which eye), tumor AJCC (American Joint Committee on Cancer) stage, tumor size (basal diameter and height) confirmed by ultrasound, MRI/CT, and a detailed fundus (interior surface of the back of the eye including the retina) diagram. The radiation oncologist will then prescribe a specified radiation dose to the tumor apex, and the medical physicist will generate a treatment plan based upon all of this information. Also, the prescription dose should encompass the entire tumor volume to maximize local control while minimizing radiation to healthy tissues and organs within the vicinity.
The entire radiation oncology team, consisting of radiation oncologists, medical physicists, dosimetrists, nurses and therapists, will consult and determine the robustness of the plan and discuss any concerns they might have regarding the treatment.
Actual placement of the eye plaque is done under local and/or general anesthesia.
The tumor first must be localized and measurements are taken to confirm that the fabricated eye plaque is adequate to cover the tumor base and any uncertainties. Sutures are placed into the sclera with or without the aid of a “dummy” plaque, and the eye plaque is affixed. The eye plaque then remains in place for the preplanned duration calculated to deliver the appropriate dose at depth and then removed under local and/or general anesthesia.
A successful treatment involves the collaboration of many departments and institutions, including Norton Cancer Institute, University of Louisville surgeons, nuclear medicine, radiation safety and diagnostics.
Norton Cancer Institute is proud to offer the highest quality treatment for patients using episceral plaque brachytherapy.
Norton Cancer Institute – Downtown performs these procedures on both adult and pediatric patients.