Uveal Melanoma

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Uveal melanoma is a rare malignancy occurring in the eye. The uveal tract consists of the intraocular structures of the iris, choroid, and ciliary body. Melanoma of the iris is the least common form of uveal melanoma. Choroid melanoma is associated with the poorest prognosis. Metastasis from the choroid occurs frequently and often involves liver metastasis. Despite its rarity, uveal melanoma is the most common non-cutaneous melanoma. Though the causes of uveal melanoma are poorly delineated, exposure to ultraviolet radiation and characteristics of pigment are predicted as risk factors leading to oncogenic mutation and subsequently, the rare manifestation of uveal melanoma.

For most individuals, exposure to ultraviolet radiation comes predominantly from the sun. Solar UV radiation is recognized as a major cause of cutaneous melanoma and many ocular conditions including cataracts, macular degeneration, pinguecula, and pterygia. It is hence presumed to be the major factor of development of uveal melanoma. The usual positioning of the tumor in the center near the macula and optic nerve aids in pinning ultraviolet radiation as an etiologic agent in uveal melanoma. This is the region of the choroid where light exposure is the most direct. Case studies have also shown higher risks for individuals that frequently use tanning lamps and for individuals who infrequently use sun protection for their eyes. From these findings, it can be concluded that UV radiation exposure plays a significant role in the development of uveal melanoma.

The cornea, lens, and iris serve to protect the choroid from UV radiation acting as an effective ultraviolet filter. In adults, there is virtually no transmission of UVA or UVB radiation through the lens an...

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... to push past the G1-S checkpoint and continue through the cell cycle regardless of damage.

Uveal melanoma threatens not only the life of individuals, but also compromises their sight. While much remains unknown regarding the etiology of this rare malignancy, solar UV radiation is presumed to play a pivotal role. Susceptibility of individuals to the damaging effects of solar UV radiation varies greatly according to several predicted risk factors. Iris color, early life exposure, and chronic UV exposure are of significant consideration among risk factors for uveal melanoma. The oncogenic mutation from which uveal melanoma originates occurs in codon 209 and affects the GTP-binding protein. This early event cannot be used, however, to predict patient outcomes. Through constitutive activation of this protein, the MAPK pathway is utilized to drive cancer progression.

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