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Prognosis and survival for intraocular melanoma
People with eye cancer may have questions about their prognosis and survival. Prognosis and survival depend on many factors. Only a doctor familiar with a person’s medical history, type of cancer, stage, characteristics of the cancer, treatments chosen and response to treatment can put all of this information together with survival statistics to arrive at a prognosis.
A prognosis is the doctor’s best estimate of how cancer will affect a person, and how it will respond to treatment. A prognostic factor is an aspect of the cancer or a characteristic of the person that the doctor will consider when making a prognosis. A predictive factor influences how a cancer will respond to a certain treatment. Prognostic and predictive factors are often discussed together and they both play a part in deciding on a treatment plan and a prognosis.
The following are prognostic factors for eye cancer.
Generally, a smaller eye tumour has a better prognosis than a larger tumour. Thickness and diameter of the eye tumour are prognostic factors for intraocular melanoma. Larger and thicker eye melanomas have an increased chance of spreading (metastasizing). Melanomas less than 3 mm (0.1 inches) in thickness have a better prognosis than thicker melanomas of the eye.
Location of the tumour
A melanoma of the iris often has a better prognosis than a melanoma of the choroid or ciliary body. Iris melanomas are often found at an early stage. Choroidal melanomas have an intermediate prognosis. Ciliary body melanomas are often larger when they are first found and have the least favourable prognosis.
Eye melanomas occur as a single nodule or grow in a diffuse (spreading) pattern. Diffuse eye melanomas tend to have a less favourable prognosis than nodular melanomas because they tend to be more invasive and spread outside the sclera of the eye (extrascleral extension) or beyond the eye (extraocular extension).
Cell type is a prognostic factor for melanomas of the eye. Generally, spindle cell melanomas have a better prognosis than epithelioid and mixed cell melanoma of the eye.
Eye melanomas with cells that grow and divide slowly (cells with low mitotic activity) have a more favourable outcome than those with cells that grow and divide faster (greater mitotic activity).
Blood vessel networks
The presence of blood vessel (vascular) networks within the tumour is strongly associated with metastatic disease, so tumours with this feature have a less favourable prognosis.
It may be that people with certain chromosomal (cytogenetic) abnormalities have an increased risk of melanoma spreading from the eye. The presence of abnormalities in chromosomes 3, 6, 8 and 9 has been found in people with eye cancer. The chromosomal abnormality most often associated with a poorer outcome in people with eye cancer is a loss of chromosome 3 (monosomy 3).