Understanding Prognosis


Prognostic indicators are still not that well understood for OM although there are several predictive factors discussed in medical literature. Several factors have been identified, though, as being associated with a higher risk of developing metastatic ocular melanoma include:

  • Large tumor size
  • Ciliary body involvement (this is a highly vascularized area, meaning it has a lot of blood vessels, so the cancer cells can get to other areas of the body, such as the liver, more easily)
  • Presence of orange pigment overlying the tumor
  • Age at diagnosis
Pathological findings such as epithelioid (versus spindle) morphology is also associated with higher risk of metastasis.

Unlike melanomas of the skin, a tumor staging system is not widely used by ocular oncologists.

OM rarely spreads through the lymph system, instead it is more likely to spread hemotogenously, or through the blood. This is one of the reasons you are likely to see metasteses ("mets") appear in the liver first and also why ciliary body involvement is a likely indicator of future metastatic disease.

Chromosomal Abnormality

The genetic makeup of the tumor is also becoming a much more useful prognostic indicator.

Recent molecular genetic research has shed light on chromosomal alterations, gene expression patterns and the relationship between these patterns and overall prognosis. The most widely used predictor of metastatic disease is the detection of monosomy 3. A monosomy is any form of aneuploidy (chromosomal abnormality) with the presence of only one chromosome (instead of the typical two in humans) from a pair.

The majority of tumors with the monosomy 3 abnormality have a poor prognosis (i.e. result in metastatic disease) versus less than 5% of tumors that have not had chromosome 3 deleted. Put another way, most of the patients missing one of their chromosome 3 pairs exhibited metastatic disease.

Here is the link to a paper that states 66% of metastasizing OM tumors with the monosomy 3 abnormality have a poor prognosis: "Monosomy 3 Predicts Death but Not Time until Death in Choroidal Melanoma"

It is believed that gains on chromosomes 6 and 8 can increase the predictive value of monosomy 3 (source: Melanoma Research Foundation). A gain of 6p indicates a better prognosis and a gain of 8q indicates a worse prognosis. This information can help predict risk of developing metastatic disease and can be obtained from a fine needle biopsy at the time of treatment of the primary eye tumor, but not after brachytherapy.