Definition and Overview

Tumors or masses in the eye can be benign or malignant; they may also be primary or secondary, which develop when cancer of the breast, prostate, bowel, and lung cancer metastasize. Most cases of eye cancers are secondary.

For primary malignant eye tumors, there are two common types: melanoma, which usually occurs in adults, and retinoblastoma, which affects children.

Retinoblastoma affects either or both of the retinas, the soft tissues of the eyes that are sensitive to light, while melanoma is characterized by the uncontrollable spread and growth of melanocytes.

Eye melanoma is sometimes referred to as uveal melanoma since it tends to develop in certain parts of the uvea such as ciliary and choroid cells, which are the exact same pigment as that of the skin. It may also develop in the iris. Tests for melanoma can determine whether the cells are spindle or epitheloid cells. Although, in general, this cancer is slow growing, it has a bigger chance of spreading especially to the liver if it has epitheloid cells, which are characterized by their straight edges and round shape.

Melanoma of the eye is more common than retinoblastoma, but the prognosis is very good when it is caught early. A more specific eye cancer is lymphoma, which affects the lymph nodes.

According to the American Cancer Society, more than 2,500 eye cancers, usually affecting the orbit and the eye itself, occur every year in the United States. These cancers are more typical among men than women. Compared to other types of cancers, the five-year survival rate for people with eye tumour is about 97%.

Causes of the Condition

Eye tumors do not have a definite cause, but latest studies cite the role of genetics.

Cells that cause retinoblastomas, for example, can begin when retinoblasts (which develop while the baby is still growing in the uterus) become uncontrollable and continue to divide. This is a defect or mutation of the RB1 (retinoblast) gene, which is part of chromosome 13. However, more than 55% of the retinoblastomas are non-germinal (they are not passed on from generation to generation). About 40% are hereditary, which means at least one of the family members has been diagnosed with the same cancer. Those who have germinal retinoblastoma are more likely to develop cancers in both eyes.

In very rare cases, the same gene defect can lead to medulloepithelioma, which affects the neuroepithelium.

Although rare than skin cancer, melanoma of the eyes (or ocular melanoma) is a very aggressive form of cancer, and risk factors can include:

  • Age: As the person ages, the risk of eye melanoma also increases. It is more common among people who are at least 65 years old.

  • Race: Caucasians have a bigger probability of having ocular melanoma in the same way they are at higher risk of acquiring skin cancer. Meanwhile, white people whose irises are of lighter color, such as blue or green, are also more likely to develop the disease.

  • UV exposure: Although still unproven, some researchers suggest that regular and long-term exposure to UV light, including that of tanning beds, can also boost the risk.

  • Skin disorders: Those who have been diagnosed with a skin disorder, especially an inherited one such as dysplastic nevus syndrome, should consider regular monitoring of the eyes for melanoma.

If the cancer begins in the lymphocytes, which are part of the immune system, it is called lymphoma. It is uncommon for lymphoma to begin in the eyes.

The rest of the benign and malignant tumors, meanwhile, can occur in the muscle, glands, nerves, and eyelids. Cancers of the eyelids may be more related to skin cancer such as squamous and basal cell carcinoma than malignant tumors of the eye.

Key Symptoms

  • Pain in the eyes
  • Eye redness
  • Change of color of the pupil or iris
  • Obstructed vision
  • Vision loss
  • Pain in the eyes
  • Secretion of mucus
  • Headache

Who to See and Treatments Available

Usually, a person with pain, bulging, or redness in the eyes approach a general practitioner for initial consultation and treatment. However, in many cases, the doctor refers the patient to an ophthalmologist, a doctor who specializes in any condition affecting the eyes. The ophthalmologist may then suggest a series of tests for diagnosis. These include:

  • Genetic testing – This is performed on children who are suspected of having retinoblastoma. The examination will determine whether the patient has a defective chromosome 13.

  • Eye examination – A standard eye test using an ophthalmoscope can already identify any presence of a lump, mass, or tumour in the eyes. A sample of the tissue or cell is collected to determine if it is benign or malignant.

  • Skin biopsy – This is carried out if abnormal cells are present in the eyelids. A portion of the skin tissue is excised and studied under a microscope.

  • Imaging tests – If the doctor suspects that the tumor or mass is cancer, imaging tests such as a CT and MRI scans of the head can be requested. These should confirm whether the cancer has already spread to other nearby organs, especially the brain. Another option is an ultrasound, which uses ultrasound waves to create a more detailed image of the eyes.

If cancer is confirmed, the patient is referred to an ocular oncologist, who then determines the stage of the cancer and ideal treatment. The treatment usually depends on the size of the tumour, stage, and the overall health of the patient. Some of the most common options are:

  • Enucleation – the removal of the eye in order to eliminate the tumor. Although the muscles and other contents are present, loss of vision is irreparable.

  • Chemotherapy – a powerful drug or a combination of them (cocktail) is used to kill the cancer cells. Chemotherapy may be delivered through the vein, eye tissue (subtenon), ophthalmic artery (intra-arterial), vitreous (intravitreal) or orally (systemic).

  • Brachytherapy – also referred to as targeted or localized radiation therapy, radioactive seeds are infused near or in the tumour.

  • Cryotherapy – layers of the eyes including the retina are frozen to prevent recurrence of the retinoblastoma.
    References:

  • Dome JS, Rodriguez-Galindo C, Spunt SL, Santana VM. Pediatric sold tumors. In: Niederhuber JE, Armitage JO, Doroshow JH, et al., eds. Abeloff's Clinical Oncology. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2013:chap 95.

  • National Cancer Institute: PDQ Retinoblastoma Treatment. Bethesda, Md: National Cancer Institute. Date last modified: Dec. 6, 2013. Available at: http://cancer.gov/cancertopics/pdq/treatment/retinoblastoma/HealthProfessional.

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