There are many misconceptions about the relationship between sun exposure and melanoma, with the conventional viewpoint being that sun exposure causes melanoma.
NOT TRUE.
There are three main mechanisms through which UV radiation can potentially contribute to skin cancer:
It directly damages skin cell and melanocyte DNA, causing mutations that may lead to unrestrained growth and tumor formation,
It causes oxidative stress can damage DNA, and
It suppresses immune function within the skin that may otherwise destroy a tumor.
While all true, extrapolating these mechanisms to human sun exposure is flawed for several reasons.
Most healthy adults don’t experience immunosuppression in response to direct UV radiation.
Chronic, low-dose UV exposure to actually increases immune function through hormetic mechanisms.
Sunlight doesn’t just put out UV radiation. The red and infrared component of sunlight, which make up about half of its radiation, protect our skin from UV damage and help repair any damage that does occur.
Comment over here.