Eye Cancer

What Is Eye Cancer?

Parts of the Eye

The eye has 3 major parts: the globe, the orbit, and the adnexal structures.

The globe (eyeball) is filled with a jelly-like material called vitreous. The uvea and the retina are 2 important parts of the globe.

The uvea has 3 parts:

• iris -- the colored or pigmented part surrounds the pupil, the opening that controls the amount of light that enters the eyeball.
• choroid -- a thin, pigmented layer lining the eyeball that nourishes the retina and the front of the eye with blood.
• ciliary body -- contains the muscles inside the eye that change the shape of the lens so that the eye can focus on near or distant objects and cells that produce aqueous humor ( the fluid in the eye)..

The retina is like the film in a camera. It is in the back of the eyeball and has specialized nerve cells that are sensitive to light. These light-sensing cells are connected to the brain by the optic nerve. The pattern of light (image) appearing on the retina is sent from the retina to an area of the brain called the visual cortex, allowing us to see. Cancers that affect the eyeball are called intraocular (within the eye) cancers.

The second part of the eye, called the orbit, consists of the tissues surrounding the eyeball. These tissues include muscles that make the globe move in different directions and the nerves attached to the eye. Cancers of these tissues are called orbital cancers.

Finally, there are adnexal (or accessory) structures such as the eyelids and tear glands. Cancers that develop in these tissues are called adnexal cancers.

Cancers of the orbit and adnexa develop from tissues such as muscle, nerve, and skin and are just like their counterparts in other parts of the body. These are described in other American Cancer Society documents on cancers of muscle, nerve, skin, etc. For example, a cancer of the eyelid is usually a skin cancer like other skin cancers and is described in the American Cancer Society documents on skin cancers ("Melanoma " and "Nonmelanoma Skin Cancers"). Muscle cancer, called rhabdomyosarcoma, is described in another American Cancer Society document, "Rhabdomyosarcoma." Intraocular cancers are unique to the eye and are described here.

Types of Primary and Secondary Intraocular Cancers

Primary intraocular cancers are cancers that start inside the eyeball. Melanoma is the most common primary intraocular cancer in adults, followed by primary intraocular lymphoma. In children, retinoblastoma (a cancer arising from cells in the retina) is the most common primary intraocular cancer, and medulloepithelioma is the next most common. Retinoblastoma is discussed in a separate American Cancer Society document "Retinoblastoma." Medulloepitheliomas are extremely rare and are discussed briefly below.

Secondary intraocular cancers are cancers that have spread to the eye from another part of the body. The most common cancers that spread to the eye are breast and lung cancers. This occurs quite often when these diseases metastasize (spread). Usually these cancers spread to the part of the eyeball called the uvea. For more information on these types of cancers, refer to the specific American Cancer Society documents on these cancers.

Intraocular Melanoma (Melanoma of the Eye)

Intraocular melanoma (also called uveal melanoma) although rare, is the most common type of cancer that develops within the eyeball in adults. Melanomas of the skin are much more common than uveal melanomas and develop from pigment-producing cells called melanocytes. When melanoma develops in the eyeball, it is usually in the part of the uvea called the choroid. Choroid cells have the same kind of pigment as melanocytes in the skin, so it is not surprising that these cells sometimes form melanomas. Approximately 90% of intraocular melanomas develop in the choroid.

Nearly all of the remaining 10% of intraocular melanomas are melanomas of the iris. They are the easiest for the patient and doctor to see because they often arise in a pigmented spot on the iris that has been present for many years and then begins to grow. These melanomas usually are relatively slow growing, and they rarely spread to other parts of the body. For these reasons, people with iris melanomas generally have a good prognosis (outlook for survival).

Intraocular melanomas are generally composed of 2 different kinds of cells.

• spindle cells -- These are elongated cells.

• epithelioid cells -- These cells are almost round but with some straight edges.

Most of the tumors are composed of both kinds of cells. The outlook is best if the tumors are mostly spindle cells and worse if they are mostly epithelioid cells. Epithelioid tumors are more likely to metastasize (spread) to distant sites and be fatal. If you have ocular melanoma, your doctor can tell you which type of cells were found.

Primary Intraocular Lymphoma (Lymphoma of the Eye)

Lymphoma is a type of cancer that generally starts in lymph nodes, which are bean-sized collections of immune system cells. Lymphomas can also start in internal organs such as the stomach, lungs, and rarely in the eyes. There are 2 main categories of lymphoma -- Hodgkin disease and non-Hodgkin lymphoma. Primary intraocular lymphoma is always a non-Hodgkin lymphoma. Most people with primary intraocular lymphoma are elderly or have immune system problems such as the acquired immunodeficiency syndrome (AIDS). For more information about non-Hodgkin lymphoma in general, refer to the American Cancer Society document on that subject.

Medulloepithelioma

Medulloepithelioma is a very rare tumor that usually occurs in young children. Although most medulloepitheliomas are malignant, they rarely metastasize (spread). They usually cause eye pain and decreased vision. The diagnosis is made when a doctor finds a tumor mass in the eye by using an ophthalmoscope (instrument that helps doctors to look inside the eye). A biopsy (a procedure in which cells from the tumor are removed and examined under a microscope) is often performed to confirm the diagnosis. Treatment is with surgery. The doctor normally tries to remove only the tumor. If that is not possible, then the eye is removed.

Do We Know What Causes Eye Cancer?

During the past few years, scientists have made great progress in understanding how certain changes in a person's DNA can cause cells to become cancerous. DNA carries the instructions for nearly everything our cells do. We usually resemble our parents because they are the source of our DNA. However, DNA affects more than our outward appearance. It influences our risks for developing certain diseases, including some kinds of cancer.

Some genes (parts of our DNA) contain instructions for controlling when our cells grow and divide. Genes that promote cell division are called oncogenes. Others that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. DNA mutations (defects) that activate oncogenes or inactivate tumor suppressor genes can cause cancer. Some people with cancer have DNA mutations they inherited from a parent. These mutations increase their risk for the disease. Usually, however, DNA mutations are acquired during life rather than inherited before birth.

Scientists have found several changes in oncogenes and tumor suppressor genes in cells from eye cancers such as melanoma and lymphoma. However, they are still not certain why these changes occur in some people, exactly how the changes occur, and how the changes cause or promote cancer formation if at all.

Can Eye Cancer Be Found Early?

Often melanomas of the eye are found during a routine eye exam. When the doctor looks through the pupil at the back of the eye, he or she may be able to see a dark spot that may indicate an early melanoma. Because they are rare, there is no screening test for them other than routine eye exams. People who find a dark spot on their iris (colored part of the eye) that is enlarging should have a doctor look at it.

Many doctors feel that skin and eye melanomas start from a nevus, which is a benign (non-cancerous) tumor of pigment cells. (Nevus is the medical name for a mole -- the plural form is nevi.) If an eye nevus is present, it should be observed regularly by an ophthalmologist (specialist in eye diseases).

How Is Eye Cancer Treated?

his information represents the views of the doctors and nurses serving on the American Cancer Society's Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.

The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.

Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don't hesitate to ask him or her questions about your treatment options.

After an eye cancer is found and staged, the cancer care team will recommend a treatment plan. In choosing a treatment plan, factors that are considered include the location and stage of the cancer, as well as a person's overall physical health. Certain treatment options may involve the risk of some loss of vision, which must also be considered.

Because intraocular melanomas and lymphomas are rare, it is often a good idea to seek an opinion from a doctor who has had a lot of experience in treating people with these cancers. A second opinion can provide more information and help a person feel more confident about the treatment plan that is chosen.

Because any treatment of the eye may interfere with or cause complete loss of vision, many treatments have been developed to preserve it. Cancers of the eye, however, can be fatal and treatment in some cases must be given regardless of the damage to the eye. On the other hand, some eye melanomas are small, grow very slowly if at all, and can be watched carefully without treatment. It is important to get the opinion of a skilled specialist in this field.