Cancer of the eyes is relatively rare compared with other types elsewhere in the body. However, cancer of the eyes usually develops into tumors.
A tumor may be found in the eyeball, the orbit, or the eyelids. Because ocular tumors are often hidden deep in the eye, they cannot be biopsied, making it difficult to differentiate between a malignant and nonmalignant (benign) tumor.
Cancerous, or malignant, tumors differs from benign tumors in several ways. Cancerous cells are unlike their surrounding tissue, often growing quickly and uncontrollably, rarely stop growing, and tend to spread (metastasize) to other parts of the body. Malignant tumors, no matter where they are located, threaten life as well as vision.
Malignant tumors of the eyelids include the basal-cell carcinoma and the squamous-cell carcinoma. The more common basal-cell carcinoma, the result of sun damage to the skin, first appears as a slight bump on the eyelid, later developing into a saucer-like shape with a raised edge. Since the tumor is on the eyelid, it is easy to remove and submit to biopsy. If left untreated, the tumor may spread to the underlying bone. Advanced basal-cell carcinomas are treated with radiation therapy.
Squamous-cell carcinomas appear much like basal-cell carcinomas, but can be distinguished through biopsy. This type of tumor tends to spread to the lymph nodes of the upper or lower eyelid and may metastasize to other parts of the body.
Rhabdomyosarcoma is a highly malignant tumor of the orbit. It is a rare form that develops in children. The tumor spreads rapidly, but can be detected by a biopsy taken through the eyelid. Treatment may include radiation or chemotherapy, and cure rates range from 30% to 40%.
The three most common types of malignant tumors are malignant melanoma, retinoblastoma, and metastatic tumors.
- Malignant melanoma, or intraocular melanoma, is the most common of all tumors that originate in the eye. Little is known concerning the cause of malignant melanomas. Unlike skin or conjunctiva melanomas, sunlight exposure is not related to these tumors. This type grows from melanin-laden cells in the choroid, iris, or ciliary body. Usually slow to grow and metastasize, it generally affects one eye only and may develop spontaneously or from a mole within the eye. The onset may be at any age, and it is more common among whites than blacks and more often in people who have skin melanoma. According to the US Department of Health and Human Services, malignant melanomas account for up to 80% of all eye malignancies, making them the most common primary (originating in the eye) inner-eye tumor. Nevertheless, little is known about the cause and progression of these tumors.Symptoms include redness, inflammation, loss of vision, and the presence or development of glaucoma. Pupil distortion may be present in melanoma of the iris. A melanoma can be detected in an examination. It may first appear to be a choroidal hemorrhage, but can be identified further by fluorescein angiography or ultrasonography. Melanomas of the iris are extremely slow-growing and are often treated during observation. Approximately 60% of those diagnosed and treated for malignant melanomas are alive five years after treatment.Clinical trials to test other treatment methods are ongoing; but three types of treatment are commonly used: surgery, radiation therapy, and photocoagulation.
- Surgery is the most common treatment, which can involve removing all of the diseased eye (enucleation) or just a portion of it.
- Radiation uses X-rays and other high-energy rays to kill cancer cells and shrink tumors. It can be used by itself, or in combination with surgery.
- Photocoagulation treats the melanoma by destroying blood vessels with a tiny beam of light, usually from a laser. Destroying the blood vessels kills the tumor.
Retinoblastoma is the most common type of malignant intraocular tumors found in children. This type occurs in one out of every twelve to twenty thousand children and develops in the retina of the eye. Retinoblastomas may be hereditary or may develop sporadically. The less common hereditary type is usually present at birth and has its onset near one year of age. In both types, the condition is almost always expressed by the age of five and is often bilateral. Although hereditary retinoblastomas are present in family histories, any occurrence of bilateral retinoblastoma should be considered hereditary and capable of being passed to further generations. Infants of such families should be screened regularly for tumors. Sporadic tumors are not hereditary. They appear at approximately two years of age and generally affect only one eye.
The first symptoms include redness, pain, and inflammation. As the tumor grows, the eyes may cross and the pupil may change from black to white or gray, a condition called leukokoria. The light color is the hue of the tumor visible through the hole of the pupil.
Treatment involves enucleation, radiation, or cryotherapy (freezing treatments). In bilateral cases, the more affected eye may be removed and the other eye may receive chemotherapy or radiation treatments. If left unchecked, the tumor could grow and spread up the optic nerve to the brain.
Cause is the absence of both retinoblastoma genes on the 13th chromosome. Although it has one of the highest rates of spontaneous regression among all tumors, little is known about the cause of the regression. The cure rate for retinoblastoma ranges from 85% to 95%.
Metastatic tumors are malignant tumors that originate in other parts of the body and spread to the eyes. Among those that can metastasize to the eyes are tumors of the lung, breast, kidney, and prostate. These secondary tumors are bilateral about 25% of the time.
Symptoms include redness, pain, vision loss, or glaucoma. Often, symptoms may present themselves before those of the primary tumor. Because metastatic tumors look much like primary ocular tumors, diagnosis can be a problem. Once a metastatic tumor has been diagnosed, the primary tumor can be treated. Depending on the size and growth rate, treatment can include surgery, chemotherapy, or radiation.