Eye Cancer

Eyesight depends on a complex series of interactions between the different parts of the eye and brain. (Read about "The Eye" "The Brain") There are three different categories of eye cancer, determined by what part of the eye they affect. The three major parts of the eye that can be affected by cancer are the globe, the orbit and the adnexal structures. The American Cancer Society (ACS) identifies the cancers that affect them as follows:

• The globe is the eyeball itself and includes such important parts as the retina, iris, etc. Cancers that affect the eyeball are called intraocular (within the eye) cancers.
• The part of the eye called the orbit consists of the tissues surrounding the eyeball, such as muscles and nerves. Cancers of these tissues are called orbital cancers.
• The adnexal (or accessory) structures include the eyelids and tear glands. Cancers in these areas are called adnexal cancers.

Orbital and adnexal cancers are in many ways like cancers that develop in other parts of the body, in that they develop from the same type of tissue, such as muscles, nerves and skin. A good example is cancer of the eyelid which the American Society of Ophthalmic Plastic and Reconstructive Surgery (ASOPRS) says is usually a skin cancer (Read about "Skin Cancer") Only intraocular cancers are unique to the eye, according to ACS.

There are two types of intraocular cancers, primary and secondary. Secondary intraocular cancers are cancers that have spread to the eye from another part of the body. Breast and lung cancer (Read about "Breast Cancer" and "Lung Cancer") are the most common cancers that spread to the eye. Primary intraocular cancers are cancers that start inside the eyeball. In adults, melanoma (Read about melanoma in "Skin Cancer") is the most common primary intraocular cancer, followed by lymphoma. (Read about "Lymphoma") In children, retinoblastoma (Read about "Cancer and Children") is the most common primary intraocular cancer, followed by medulloepithelioma (an extremely rare tumor in the eye that requires surgery).

Intraocular melanoma is also called uveal melanoma because it usually develops in the part of the eyeball called the uvea. It's a very rare type of cancer because melanomas usually develop in the skin, in pigment-producing cells called melanocytes. When melanoma develops in the eyeball, it almost always arises in the part of the uvea called the choroid, a pigmented layer lining the eyeball. This can happen because choroid cells contain the same kind of pigment as melanocytes in the skin. ACS says 90 percent of intraocular melanomas occur in the choroid. The other ten percent develop in the iris, the pigmented or colored area around the pupil. Melanomas in the iris are usually slow growing and rarely spread to other parts of the body.

Different types of treatments are available for patients with intraocular melanoma. They include surgery, watchful waiting, radiation, photocoagulation, which is also called light coagulation, and thermotherapy, which uses a laser. (Read about "Radiation Therapy")

Intraocular lymphoma also starts in the eye, and it, too, is a rare type of cancer. Lymphoma generally starts in the lymph nodes (Read about "The Lymph System"), which are groups of immune system (Read about "The Immune System") cells, all over our bodies. It is possible for it to start in internal organs but rarely, in the eyes, according to ACS. Hodgkin's disease and non-Hodgkin's lymphoma are the two main types of lymphoma. ACS says primary intraocular lymphoma is always a non-Hodgkin's lymphoma. Most people who develop it are elderly or have immune system problems such as AIDS. (Read about "HIV / AIDS")

Intraocular lymphoma treatment options generally include external radiation therapy, chemotherapy, or a combination of the two. Depending on the extent of the cancer, the radiation therapy may be directed only at the eye or eyes, or it may also include the brain and spinal cord. (Read about "The Brain" "Nervous System")

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For a list of individual types of cancer, see Cancer: What It Is