Collaborative Ocular Melanoma Study (COMS)

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Now that you see it, what do you do with it? The COMS was a prospective multicenter trial organized by the National Eye Institute in 1985 to examine mortality outcomes of different treatment options for uveal melanoma. They also examined cancer free survival, metastasis free survival, and years of functional vision. There were three main arms of the study, which differentiated melanomas based upon tumor size. It is important to note that this study is not applicable to melanomas of the ciliary body or peripapillary choroid.

Small tumor trial (1mm < height <3mm and 5mm < diameter < 16mm)

• Objective: do these patients need treatment?
• Methods: observational study with a smaller (N = 188)
• Result: mortality is low for small melanomas, tumor grows slowly
• Takeaway: small choroidal melanomas can be observed safely 

Medium tumor trial (2.5mm < height < 10mm and diameter <16mm)

• Objective: do these eyes need enucleation?
• Methods: randomized to enucleation (N = 660) vs. plaque brachytherapy with i125 (N = 657)
• Result: no difference in mortality outcomes at 5 years (enucleation = 81%, plaque = 82%, p = 0.48) so both are options
• Takeaway: plaque brachytherapy is a viable option for medium sized melanomas, long-term data for brachytherapy survival is still pending

Large tumor trial (height > 8mm and/or diameter > 16mm)

• Objective: does radiation improve mortality?
• Methods: randomized to enucleation alone (N = 506) vs. external beam radiation therapy (20 Gy) followed by enucleation (N = 497)
• Result: no difference in mortality outcomes at 5 years (57% enucleation, 62% EBRT then enucleation) or 10 years (40% enucleation, 45% EBRT then enucleation)
• Takeaway: pre-enucleation radiotherapy is no longer used as it is ineffective 

The COMS is a landmark study because it helped guide physicians on when and how to treat ocular melanomas, which are the most common primary eye tumors in adults. Although nonmalignant choroidal nevi are more common than choroidal melanomas, all nevi should be evaluated for features concerning for melanoma as choroidal melanomas have high mortality rates.