Eye Cancer MD: TREATMENT

TREATMENT

Your doctor will recommend treatment based on your medical history and the findings from the eye examination. It is not always necessary to treat all eye cancers immediately. If a tumor is very small or very slow growing, sometimes the doctor will closely monitor the tumor. If there are any concerns, then treatment can be started. Treatment usually is recommended when your physician determines that the tumor shows evidence of growth or if there is the possibility of spreading to other parts of the body if left untreated.

TREATMENT TYPES:

CHEMOTHERAPY
CRYOTHERAPY
EXTERNAL BEAM RADIATION THERAPY
RADIATION PLAQUE THERAPY
ENUCLEATION
PHOTODYNAMIC THERAPY

Chemotherapy

Although it is rarely used for eye cancer, chemotherapy is the most common type of treatment for many other types of cancer. Chemotherapy is the treatment of disease by means of drugs that have a specific toxic effect upon the cancer cells. Chemotherapy selectively destroys cancerous tissue.

There are many chemotherapeutic drugs available. Each type of drug has potential side effects such as skin problems, nausea, vomiting, and infections. Chemotherapy sometimes is recommended for choroidal metastasis, conjunctival tumors and lymphoma.

Cryotherapy

Cryotherapy is the use of low temperatures to treat disease. Cryotherapy is applied under local anesthesia. The goal of cryotherapy is to freeze the malignant tissues in order to stimulate inflammation and scarring of this tissue. Cryotherapy may be recommended for conjunctival or eyelid tumors.

External Beam Radiation Therapy

Radiation therapy uses high-energy radiation from x-rays and other sources to kill cancer cells and shrink tumors. Radiation that comes from a machine outside the body is called external-beam radiation therapy as opposed to radiation that is administered by placing a radiation plaque over or very near the tumor (internal radiation therapy or brachytherapy). External beam radiation therapy may be recommended for some choroidal metastasis, eyelid tumors, choroidal hemangiomas, lymphomas and orbital tumors.

Radiation Plaque Therapy (Brachitherapy)

Radiation plaque therapy is the most commonly used "eye-sparing" treatment for choroidal melanoma. A radioactive plaque is a small, gold covered, dish-shaped device that contains a radioactive source. Standard low-energy radioactive eye-plaques contain rice-sized radiation seeds that emit low energy photons. The gold coat of the plaque helps to aim the radiation photons directly at the tumor and decrease radiation damage to surrounding tissues. As the cells die, the tumor shrinks, although it usually does not disappear entirely. Radiation plaque therapy may be recommended for choroidal melanomas or iris melanomas.

Eye plaques are custom made to the dimensions of the tumor, usually ranging in size from about 12 to 22 mm. in diameter (about the size of a quarter). Careful calculations determine how long the plaque must remain in place to give the tumor the proper amount of radiation.

A custom-made radiation plaque. On the left is the inside of a plaque with the radiation seeds. On the right is the gold coating on the outside of the plaque.

Surgical placement of the plaque lasts about an hour and usually is performed under local anesthesia. During surgery, an incision is made in the conjunctiva and the radioactive plaque is sutured to the sclera, outside of the eye, over the tumor. The conjunctiva is then sewn back over the plaque. Patients remain in the hospital for about three to five days at which time the plaque is surgically removed.

Most patients have no problems associated with plaque surgery. As with any ocular surgery, there can be secondary complications such as retinal detachments, hemorrhages, or infections. There are also risks associated with anesthesia.

The effects of radiation on the tumor typically are first evident three months after treatment. Eventually, eye melanomas shrink to about 40% of their pretreatment size. After successful treatment, although the tumors rarely completely disappear, they are considered to be inactive.

After radioactive plaque treatment, many patients note some dryness and irritation of the eye. In some instances, eyelashes may be permanently lost. In rare instances, the outside layer of the eye (sclera) may become very thin. Occasionally, prolonged redness, irritation, or infection may occur. Some patients may experience double vision, which can last a few days or several months. Radiation plaque therapy may cause eventual blurring, dimming, or rarely a total loss of vision in the treated eye. Plaque radiation does not affect the vision in the other eye. The amount of vision loss depends on what your vision was before treatment, how close the tumor is to the area of central vision of the eye, and how sensitive your tissues are to radiation. Most people maintain some central vision, and almost all retain peripheral vision.

Enucleation

The term enucleation may sound like an atomic bomb will be used to remove the eye, but the term simply means surgery for the removal of the eye. Enucleation is the surgical removal of the eye, leaving eye muscles and the contents of the eye socket intact. The eyelids, lashes, brow and surrounding skin all remain.

This procedure is done when there is no other way to remove the cancer completely from the eye. Unfortunately, loss of vision for the eye removed is permanent because an eye cannot be transplanted. The eye is removed, and a spherical implant made of coral or hydroxyapatite is placed into the orbit. This allows the blood vessels to grow into the porous coral material. The muscles that help give movement to the eye are then sutured to the implant, which will allow for some movement of the prosthesis.

After the eye is removed, an implant made of hydroxyapatite is implanted into the orbit.

The eye is surrounded by bones; therefore, it is much easier to tolerate removal of an eye as compared to the loss of other organs. After a healing period, a temporary ocular prosthesis (plastic-eye) is inserted. The prosthesis is a plastic shell painted to match the other eye. It is inserted under the eyelid, much like a big contact lens. After a final prosthetic fitting most patients are happy with the way they look, and say others can't even tell they have vision in only one eye.

After enucleation, there is reduced visual field on the side of the body when looking straight ahead, and there is a loss of depth perception. Many of the skills of depth perception can be relearned and with time, almost all patients are able to do all the things they used to do before losing their eye. A few people who did very well with only one eye include: President Theodore Roosevelt, Israeli military leader Moshe Dayan, Congressman Morris Udall, entertainer Sammy Davis Jr., actor Peter Falk, painter Edgar Degas, aviator Wiley Post, inventor Guglielmo Marconi and British naval hero Horatio Nelson.

Can you tell which is the artificial eye?

Photodynamic Therapy

Photodynamic therapy (also called PDT) is a treatment that can potentially destroy unwanted tissue and is sometimes used to treat choroidal hemangiomas. PDT destroys cancer cells with a fixed-frequency laser light in combination with a photosensitizing agent that is injected into the bloodstream. The photosensitizing agent alone is harmless and has no effect on either healthy or abnormal tissue. However, when laser is directed onto tissue containing the drug, the drug becomes activated and the tissue is rapidly destroyed. The laser light used in PDT is directed through a fiber-optic placed close to the hemangioma to deliver the proper amount of light and selectively target only the abnormal tissue.

An advantage of PDT is that it causes minimal damage to healthy tissue. However, PDT makes the skin and eyes sensitive to light for about 6 weeks after treatment. Patients are advised to avoid direct sunlight for at least 6 weeks after PDT treatment.