While we routinely diagnose cancerous lesions on the skin surrounding the eye, we encounter less than ten cases of cancerous tumors within the eye each year. Choroidal melanoma is the most common and most treatable form of ocular cancer, although treatment varies by tumor size.
Despite medical advances, the therapy for large choroidal melanoma tumors is still removal of the eye (enucleation), with five-year survival rates of approximately sixty percent. However, we are able to treat small and medium tumors with brachytherapy, a technique where a plate of radioactive iodine seeds is sutured onto the back of the eye over the base of the tumor. The radioactive seeds remain in place for three to five days and are then removed.
Brachytherapy has been the subject of an ongoing clinical study, the Collaborative Ocular Melanoma Study (COMS), funded by the National Eye Institute. A summary of this clinical study can be found at Collaborative Ocular Melanoma Study (COMS) [NEI Clinical Studies]. Over 1,500 patients with small and medium ocular melanoma were treated from 1986 to 1998 with either brachytherapy or enucleation, and these patients are now being tracked to measure mortality rates and visual function. Preliminary results indicate the five-year survival rates for both treatments are similar (greater than eighty percent). Consequently, brachytherapy may be the superior treatment for small and medium tumors since it allows patients to retain at least partial function of the affected eye.
Brachytherapy, chemotherapy and enucleation are treatment options for retinoblastoma, another form of cancer, but all other types of ocular cancer are generally just monitored. Metastatic cancer, or cancer that spreads from other parts of the body, is the second most common form of ocular cancer, but this is rarely treated because an oncologist’s first priority is to treat the primary sources of cancer.