A uveal malignant melanoma, also known as a uveal melanoma or ocular melanoma, is a malignant tumor in the eyes. This is the most common type of eye cancer. The cancer usually affects the uvea; the middle layer of the eye between the retina and the white of the eye). The risk of metastases and death is quite high with this type of cancer, also because the patient often has few or mild symptoms and no pain in the early stages of the cancer. The treatment consists of removing the eye or applying chemotherapy and/or brachytherapy in which the ophthalmologist spares the eye. The prospects are very variable and range from very good to very poor.
- Epidemiology of uveal malignant melanoma
- Types of melanoma in the eye
- Risk factors for cancer in the eye
- Eye tumor location
- Symptoms: Mild in early stages
- Diagnosis and examinations
- Treatment: Surgery, chemotherapy, brachytherapy and radiotherapy
- Prognosis of eye melanoma is poor if it has spread
- Prevention of ocular melanoma
Epidemiology of uveal malignant melanoma
Uveal malignant melanoma is the most common eye tumor in the white population. The incidence is on average 5.1 per million patients. As patients age, the incidence increases. Most patients are between their fifth and sixth decades when the ophthalmologist makes the diagnosis. Children are almost never affected by uveal malignant melanoma. People of African and Asian descent are also rarely affected. The tumor appears most often in the Caucasian breed.
Types of melanoma in the eye
Most melanomas affect the skin, but sometimes the tumor occurs in other parts of the body, including the eye. If cancer starts in the eye, it is known as ‘primary eye cancer’. If the eye melanoma starts elsewhere in the body and then spreads to the eye, it is called ‘secondary eye cancer’. Uveal melanoma is usually secondary, and in 9 out of 10 patients with uveal melanoma, the cancer starts in the skin.
Risk factors for cancer in the eye
Some factors increase the risk of developing uveal malignant melanoma, in particular:
- exposure to the harmful UV rays of sunlight
- skin color: freckles, white skin color, easy burns and inability to tan
- the iris color: People with blue eyes have a higher risk of developing ocular melanoma than people with brown eyes (eye color).
- a family history of uveal melanoma
- a mole in the eye (ocular nevi)
- a Northern European descent
- an older age
- Dysplastic nevus syndrome: A patient develops atypical moles with irregular borders, possibly of various colors. These spots often appear in groups (clusters).
Eye tumor location
The eye tumor arises in one eye (unilateral). The tumor usually arises at the level of the choroid, the choroid of the eye. A tumor may also develop in the ciliary body. Occasionally the tumor arises in the iris of the eye.
Symptoms: Mild in early stages
When the tumor arises on the choroid, the position of the retina changes upwards. The lifting affects peripheral vision. This is the image a patient sees from the side. Very often, however, the patient is asymptomatic until the macula moves due to tumor growth. The macula is therefore lifted, which affects the patient’s central visual acuity. The patient usually has no pain with the uveal malignant melanoma . Increased intraocular pressure may develop in the end stage, which may be accompanied by eye pain, headache and reduced or blurred vision and watery eyes. Sometimes a dark spot can be seen in the iris that slowly enlarges. Reduced visual acuity, floaters (seeing floaters, mouches volantes in the eyes), photopsia (seeing stars and flashes of light) and visual field defects are other possible symptoms that usually only become apparent at a later stage of the cancer.
Diagnosis and examinations
Often the patient has few or mild symptoms, making the diagnosis a challenge for the ophthalmologist. In many cases, the diagnosis is made by chance when the ophthalmologist performs a standard eye examination and views the back of the eye via ophthalmoscopy (viewing examination of the eye structures) for other indications.
The ophthalmologist performs an ophthalmoscopy (examination of the back of the eye) and notices a subretinal elevation (without retinal tear). Fundus photography is essential for detecting and monitoring ocular lesions at the back of the eye. An eye ultrasound is also necessary. The doctor also performs a fluorescent angiography to visualize suspicious lesions. An OCT scan uses light waves to take slices of the retina and sometimes the choroid, revealing possible swelling or the presence of fluid under the retina. Rarely is a biopsy (removing a piece of tissue) of the tumor necessary to diagnose this type of melanoma.
During eye examinations it is virtually impossible to determine the metastases (spreads) of the tumor. However, the metastases are often present. In uveal malignant melanoma, the metastases are most often in the liver (liver metastases).Further tests determine whether the cancer has spread to other parts of the body. These include:
- a biopsy in which the doctor takes a tissue sample for further examination in a laboratory. A biopsy is usually not necessary.
- a blood test, to determine whether the cancer has spread to the liver (liver metastases)
- a CT scan or MRI scan of other body parts
- an x-ray of the chest (chest x-ray) to determine abnormalities in the lungs (lung metastases)
Metastases from tumor elsewhere in the body The series of symptoms of a uveal malignant melanoma is very similar to metastases that occur with another primary tumor that originated elsewhere in the body. Examples of this are mammacracinoma (breast cancer) or bronchus carcinoma (lung cancer). The signs of metastases in the choroid are very similar to the metastases of tumors arising elsewhere in the body. This often causes multiple lesions in both eyes. It happens that the ophthalmologist notices the symptoms of the metastases, but the primary tumor has not yet been identified.Other Differential Diagnoses Other differential diagnoses include:
- congenital hypertrophy or reactive hyperplasia (overgrowth) of the retinal pigment epithelium
- diffuse melanocytic proliferation and pigment epithelium, retina or choroid that are loose
- a Fuchs’ adenoma (usually benign glandular tumor)
- a benign nevus (birthmark)
- a granuloma
- a hamartoma of the retina and retinal pigment epithelium
- an iridociliary epithelial cyst (abnormal fluid-formed bladder-shaped cavity in the body)
- a leiomyoma: Growth of smooth muscle tissue
- a melanocytoma
- an ocular hemangioma (benign blood tumor around the eye)
- a primary iris cyst
- a sarcoid nodule
- a foreign object in the eye (eye trauma)
- essential iris atrophy
- peripheral anterior synechia: adhesions between eye structures
Treatment: Surgery, chemotherapy, brachytherapy and radiotherapy
Treatment depends on several factors, including the type of tumor, the size of the tumor, and the patient’s general health.
Sometimes the doctor does not treat the cancer when there is a minor lesion because treatment affects vision. The ophthalmologist then monitors the patient closely.
The ophthalmologist removes the entire eye from the eye socket when there is a large tumor. This surgical procedure is known as an enucleation. After the operation, the patient is eligible for an eye prosthesis. Another option is an eye-sparing treatment technique. This is especially effective for small melanomas. The ophthalmologist treats the tumor with plaques of radioactive isotopes (ruthenium, strontium) that he temporarily attaches to the sclera (hard sclera). This treatment technique is known as brachytherapy. Occasionally the ophthalmologist uses another eye-sparing surgical technique (tumorectomy). Chemotherapy is usually required and when there is a solitary injury, radiotherapy of the eye is indicated.
Prognosis of eye melanoma is poor if it has spread
The outlook for uveal melanoma is highly variable and depends on many factors:
- certain changes in genes linked to melanoma,
- the patient’s general health,
- the size and thickness of the tumor,
- the amount of tumor occurrence,
- the age of the patient
- the spread of the tumor in the eye or other places in the body,
- the part of the eye in which the tumor is located (the iris, ciliary body or choroid) and
- the appearance of the tumor under the microscope.
According to the American Cancer Society, the five-year survival rate is 80%. However, if metastases are present in other parts of the body, this percentage drops to 15%.
Prevention of ocular melanoma
To reduce the risk of skin cancer and eye cancer, it is recommended to protect yourself from strong sunlight by using sunglasses with UVA and UVB protection, sunscreen and a hat. Sunshine and outdoor work are not proven causes of eye cancer, but they do increase the risk of a malignant tumor in the eye.
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- Eye tumors: Retinoblastoma, melanoma, lymphoma of the eyes
- Eye Cancer: Types and Symptoms of Malignant Eye Tumors
- Eye lymphoma (intraocular lymphoma): Cancer in the eye or eyes
- Radiotherapy (irradiation) for cancer in the eye