Eye cancer. Close up of the eye of a patient with malignant (cancerous) melanoma (dark brown) of the iris. The cancer has arisen from cells that produce the pigment (melanin) that gives the iris its colour. Melanomas are invasive cancers, and may spread to other parts of the body (metastasis). If this occurs, the prognosis is poor. If the cancer has not spread, surgical removal may effect a cure.