According to research funded by Cancer Research UK and others, ultraviolet radiation (UVR) has been found to cause a rare type of eye cancer – conjunctival melanoma.
Melanomas are a heterogeneous group of tumours that can be broadly classed as epithelium-associated melanomas and non-epithelium associated melanomas. Non-epithelium associated melanomas have distinct clinical and genomic features. Even among epithelium-associated melanoma, the frequency and combinations of genomic alterations can vary between subtypes.
UVR-induced DNA damage is a clinically relevant factor that distinguishes the different melanoma subtypes. There is a clear link between UVR and the development of common cutaneous melanoma. However, its contribution to the rare subtypes is largely assumed to be negligible. This is because they tend to arise in sun-protected tissues.
Mucosal melanoma is a rare melanoma subtype that accounts for 1.4% of melanomas. It arises in the mucosa of the eyes, mouth, nose and gastrointestinal and genitourinary tracts. It responds poorly to treatment and is characterised by distinct genomic traits, including high number of chromosomal structural changes, low mutational burden and specific patterns of driver oncogenes. This was thought to be because mucosal melanomas arise in distinct microenvironments and are not driven by UVR.
UVR-exposed mucosal melanomas
In a study, published in Nature Communications, researchers performed whole-genome sequencing on mucosal melanomas from the conjunctiva (tissue largely UVR exposed) to test the hypothesis that UVR drives melanomagenesis independent of tissue microenvironment.
The data showed similar genetic changes in conjunctival melanoma to that of cutaneous melanoma. Specifically, it revealed a predominance of UVR-associated single base substitution signature 7 (SBS7) in the majority of the samples. These findings suggest that treatments used for skin melanoma may also benefit people with this rare form of eye cancer.
This study has emphasised the importance of how understanding the fundamental biology of more common cancers can in fact help people with rare diseases that are often more difficult to study. Not only this, it also reinforces the dangers of UV radiation.
Professor Richard Marais, CRUK Manchester Institute, stated:
“By showing that UV radiation can cause conjunctival melanoma, we have added to our understanding of the known dangers of the sun for our eyes. It reminds us of the importance of protecting not just your skin, but also your eyes from UV light, be it in everyday life, or where the UV radiation is particularly high and causes the most damage such as on the beach, on a boat, on a mountain.”
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