Intraocular Tumors

		Preliminary Results of Combined Simulataneous Transpupillary Thermotherapy and ICG-Based Photodynamic Therapy for Chorodial Melanoma.

What types of tumors affect the eye?

Malignant tumors can metastasize to the eye, just as they can metastasize to other parts of the body. The most common cancers that affect the internal structures of the eye originate in the breast, lung, prostate, and bone marrow (leukemia). Typically, these cancers cause tumors within the eye after the cancer has been diagnosed elsewhere. Metastatic tumors within the eye are usually treated with systemic chemotherapy, which also fights the cancer in other parts of the body. Occasionally, radiation therapy has been used to treat the eye more directly.

Tumors can also originate within the eye itself. The most common primary malignant tumor that occurs in the adult eye is a choroidal malignant melanoma (see photo above). This typically occurs silently in patients at an average of 55 and older. It occurs much more frequently in Caucasians. Sunlight does not appear to play a role in the development of these cancers as it does in skin melanoma.

What is a choroidal melanoma and how is it diagnosed?

Nowadays, most people are familiar with melanoma as a very dangerous type of skin cancer involving the melanocytes that give the skin its pigmented color. Skin melanomas are associated with unprotected exposure to the sun, especially in youth. Unlike skin melanomas, choroidal melanomas have not been linked to sun exposure, but they are more common in persons with lighter skin pigment. Similar to skin melanomas, intraocular melanomas are believed to arise from small benign pigmented areas called nevi. An intraocular nevus is best examined by dilating the pupil of the eye and looking with special lenses. Photographs, including specialized digital imaging, may also be taken to compare to future exams for any changes. If a pigmented area within the eye becomes larger and thicker, an ultrasound is usually performed to measure the area and check for characteristics suspicious for a malignant melanoma.

How are choroidal melanomas treated?

In the past, the only treatment available for intraocular melanoma was to remove the eye. Today, this is usually not necessary, and more conservative measures can be employed that treat the tumor and save the eye. Currently, we are the only practice in Connecticut treating intraocular melanomas with the eye sparing advanced techniques of radioactive plaque therapy and transpupillary thermal therapy.

What is radioactive plaque therapy?

A radioactive plaque looks like a flattened gold penny with a central bump. In the bump is a small amount of radioactive iodine (I-125). This radioactive iodine is shielded on three sides so the radioactivity is directed only at the wall of the eye, and not at any of the structures around the eye. Typically, the size and shape of the plaque is planned out by the treating retina specialist with the help of a radiation oncologist (a physician who specializes in the treatment of cancers with radiation). The individualized plaque is then sewn onto the sclera (the white part) of the eye so that it lays over the tumor. After several days of this directed, localized radiation treatment, the plaque is removed. In the past 20 years, episcleral radioactive plaque therapy has become the most widely used treatment modality for choroidal malignant melanoma, obtaining a five year survival rate of >75%. Unfortunately, the advantages of this type of radiation therapy can be negated by the development of chronic radiation-induced complications to the eye. These may occur in >20% of patients, and include cataract, radiation retinopathy, optic neuropathy, and neovascular glaucoma, and eventually may impair ocular function.

Transpupillary Thermotherapy

To reduce the rate of secondary complications, we feel that intraocular tumors are best treated by a combined modality treatment beginning with Transpupillary Thermotherapy (TTT). In TTT, a near-infrared 810 nm wavelength laser destroys the cancerous cells by concentrating a very focused hot beam (between 45 and 60 degrees C) on the tumor, leaving the surrounding, healthy tissue undisturbed. We typically use the 810 nm laser to reduce the size of the lesion over two treatment cycles, two weeks apart. Depending on the size of the tumor, we may then add argon laser (if the lesion has reduced to 3mm height), use an I-125 plaque (for lesions 3-12 mm in height), or excise the tumor if it is anteriorly located. Reduction or total eradication of the tumor is possible with this combined modality approach, and there is a significant reduction in treatment-related complications because radiation, if used, is at a lower dose. To calculate the optimum amount of radiation strength needed to kill the tumor, but not the surrounding tissues, we utilize the interactive treatment optimization program, which we developed at USC, and is now being used by the Yale Department of Radiation Oncology. Use of this optimization program has resulted in a sharp decrease in the incidence of serious post-radiation complications.

Image of a 3-D computer optimization program showing a model eye with the radioactive plaque in place calculating isodose curves.

The NIH-sponsored Collaborative Ocular Melanoma Study (COMS) showed no difference in the survival rate of patients undergoing enucleation versus radiotherapy. We thus believe that conservative treatment with radioactive plaque placement is the preferred method for treating medium-sized tumors in order to spare the eye.