Eye Cancer

Intraocular Cancers

Intraocular cancers can be either primary or secondary. Secondary intraocular cancers are cancers that have spread to the eye from another part of the body. Breast and lung cancers are among the most common cancers to spread to the eye, usually to the uvea. In contrast, primary cancers originate inside the globe. Melanoma is the most common primary intraocular cancer in adults, followed by lymphoma. Melanomas of the eye are classified as anterior when arising in the iris and posterior when arising in the choroid or ciliary body. Ninety percent of intraocular melanomas are posterior choroidal, with nearly the remaining 10 percent being melanomas of the iris. Posterior choroidal melanoma arises from melanocytes in the choroid. The incidence in the United States is approximately six cases per 1 million and is highest around age 55, although this figure varies in regions with more or less sun exposure.

Choroidal melanoma commonly results in partial or complete visual loss in the affected eye due to either tumor destruction of ocular tissues or as a consequence of treatment. It is associated with a mortality rate of 30 to 50 percent within 10 years, owing to its highly metastatic nature. There is currently no effective treatment for intraocular melanomas, although enucleation (removal of the eye while sparing orbital contents) and irradiation are potentially life saving. Primary intraocular lymphoma is the next most common intraocular malignancy in adults but remains exceedingly rare. An intraocular lymphoma is considered extranodal and is always of the non-Hodg-kin type (as opposed to Hodgkin's lymphoma). The elderly and patients with human immunodeficiency virus (HIV)/AIDS have a propensity for this cancer, likely due to their immunocompromised state. Over 80 percent of patients develop cerebral involvement, which is associated with a much poorer prognosis. Randomized treatment trials are scarce owing to the rarity of this cancer, but case reports support external beam radiation as an effective treatment.

In children, retinoblastoma is the most common primary intraocular cancer, followed by medulloepithelioma. Retinoblastoma is a tumor of the retinal photoreceptor precursor cells. It occurs due to mutations in the RB1-gene, although only 5 percent of patients who develop the disease have a positive family history. It has an incidence of approximately 11 per 1 million children worldwide. It occurs mostly in children younger than 5 and accounts for three percent of all neoplasms in children under 15. Retinoblastoma can be unilateral or bilateral and is usually first detected by leukocoria (a white papillary reflex replaces the normal red-light reflex). Visual disturbances are often noted because of the intrinsic retinal involvement of this cancer. Management varies per patient and includes radiation, neoadjuvant chemotherapy, and surgery. The most important prognostic factor remains early detection, resulting in survival rates of approximately 86 to 92 percent. Extraocular extension through the sclera or along the optic nerve is associated with higher mortality. Unfortunately, highly advanced cases of retinoblastoma are still seen in the developing world. This can be attributed to neglect, poverty, cultural beliefs, politics, health-seeking behavior, and so forth.

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