How Uveal Melanoma is Diagnosed
Uveal Melanoma is most commonly diagnosed by an ophthalmologist (eye doctor) using a variety of tests. A routine eye exam is the best option for identifying potential issues .
Routine Eye Exam
An eye exam is performed by an optometrist or ophthalmologist and is a painless procedure. The outside and inside of the eye are examined for any abnormalities. Special eye drops that dilate the pupil may be used to help see the inside of the eye. A diagnosis of uveal melanoma can sometimes be made by eye exam alone.
Other diagnostic tests and aids can include:
Different types of specialised photographs are used to take pictures of the outside and inside of the eye and can help in diagnosing eye conditions, such as uveal melanoma. By comparing photographs before and after treatment, they can also help determine whether the treatment given has been effective.
Ultrasound uses high frequency sound waves to help see inside of the eye. Anaesthetic eye drops may be used to numb the eye so that an ultrasound probe can be placed on the eyes surface. An ultrasound can be useful in determining a tumours size, shape and location.
Using a light placed on the surface of the eye, eye structures are examined for any abnormalities.
A procedure to look at blood vessels and the flow of blood inside the eye. An orange fluorescent dye (fluorescein) is injected into a blood vessel in the arm. As the dye travels through blood vessels of the eye, a special camera takes pictures of the retina and choroid to detect any blockage or leakage.
Imaging of the eye
Other sensitive imaging techniques are sometimes used to see subtle changes in a tumour and nearby structures. Some of these imaging techniques include; Optical Coherence Tomography, Infrared Fundus Photography, Indocyanine Green Angiography and Fundus Autofluorescence
Imaging of the body
If it is suspected that the uveal melanoma has metastasised (spread) you may have imaging scans of the rest of your body, this may include; X-Rays, these allow visualising of internal body structures. A 3D x-ray called Computed Tomography (or CT) may be taken of certain parts to better visualise if there is any spreading (metastasising) tumour. Magnetic Resonance Imaging (MRI) may also be used to create a 3D image, it takes longer than a CT but does not use any radiation.
A blood sample may be taken to determine how well organs in your body are working. Analysing the blood may help determine whether the tumour has spread.
A biopsy is a way to get to a sample of the tumour cells, usually by using a fine needle. It is not typically performed for a uveal melanoma diagnosis as other tests are usually enough to confirm the diagnosis.
A biopsy may be performed so that the cells can be analysed by a medical geneticist to study the tumours DNA. This information could be useful in determining survival prognosis of the patient and their eligibility for clinical trials.
Uveal Melanoma Staging
There have been several categorisation systems of uveal melanoma according to their dimensions, cellular type or genetic defects, and their link to the potential for spread outside the eye. The current most practical staging for uveal melanoma is called the TNM staging system that rates the size, location and extent of the tumour.
With the TNM details, uveal melanoma can be “staged” into 4 different groups with different implications for clinical care. In general, it can be localised (Stage 1, 2), locally invasive (stage 3) or spread to other parts of the body (stage 4).
Prognosis is a term used to help predict the likely outcome of a patient with a health condition. Prognosis can refer to the likelihood of a patient surviving after the diagnosis of a tumour. There are a number of factors that go into determining a prognosis for a patient. Some of the factors that influence the prognosis in uveal melanoma are listed below.
Factors influencing prognosis
- Tumour size: The larger the tumour, the less favourable the prognosis.
- Tumour location: Iris melanomas have a better survival prognosis than ciliary body melanomas; the prognosis for choroidal melanomas is in between iris and ciliary body melanomas.
- Metastases (Spreading): A tumour spreading outside the eye wall or to other parts of the body has a worse prognosis.
- Recurrence (Return of the tumour): Sometimes a tumour can return after treatment. This is called relapse or recurrence. This is associated with a worse prognosis as the tumour may no longer respond to treatment, and has been shown to have an increased likelihood of spreading.
- Genetic factors: This is the most important determinant of survivability chances in uveal melanoma. Changes in the DNA and changes in specific tumour genes may have a role in prognosis and can be determined by genetic testing. A biopsy is needed to do genetic testing. If you are interested in genetic testing and to confirm whether you are an eligible candidate, speak with your doctor.
- The patient: Age, general health status and other medical conditions can all play a part in prognosis. You can discuss your personal factors with your doctor.
Will my vision be affected?
Certain factors may affect vision after your treatment, these can include:
- Tumour size: A larger tumour increases the risk of vision loss
- Tumour location: A tumour closer to the optic disk or macular increases the risk of vision loss
- Other medical conditions: Other medical conditions such as, certain eye conditions and diabetes, uncontrolled hypertension increase the risk of vision loss.
Each cell in the human body contains a set of instructions (genes); these genes are stored in structures called chromosomes. Healthy cells have two copies of each chromosome. Cells that are abnormal often show changes in these chromosomes. These abnormal cells multiply at a higher rate and are considered to be cancer cells.
One of the most important indicators of poor prognosis in uveal melanoma is loss of chromosome 3 (monosomy 3). Metastatic disease develops almost exclusively in patients with this genetic abnormality. Other chromosomes that can be altered in uveal melanoma tumour cells are chromosomes 1, 6 & 8.
Approximately 50% of these tumour cells will show chromosomal abnormalities; these types of tumour cells have a high risk to spread (metastasise) outside of the eye. Tumour cells that show normal chromosome numbers have a low risk of metastasising.
While these chromosome changes are genetic changes, they are not inherited (passed through the family). These chromosome changes occur by chance in the tumour cell of the eye. They are not present in any other parts of the body, specifically the egg or sperm cells, and therefore cannot be passed on to children.
Genetic testing of uveal melanoma tumour cells is performed by obtaining a sample of cells from the affected eye. This can be done at the time of plaque radiation therapy or taken from a removed eye. This sample is performed by your surgeon and sent directly to the laboratory.
At times, biopsies taken from the eye for genetic analysis contain both healthy and tumour cells. For this reason, a second test may be performed to confirm the test by proving that the cells analysed are indeed tumour cells and not healthy cells that may have been in the sample.