Hi, I came across this subtject a few times before. As an out door worker I was exposed to the sun many hours every day and sofar I have been lucky that I don't  have any damaged skin. I had one spot on my nose which I think is gone with the treadment of Hemp Oil. It is funny (maybe not )

that people get a melanoma on places of the body were the sun don't shine. Here is one explanation why it is so,

There are two major factors that help explain this, and the first has to do with the type of UV exposure.

There are two primary types of UV rays from sunlight, the vitamin-D-producing UVB rays and the skin-damaging UVA light. Both UVA and UVB can cause tanning and burning, although UVB does so far more rapidly. UVA, however, penetrates your skin more deeply than UVB, and may be a much more important factor in photoaging, wrinkles and skin cancers.

A study in Medical Hypotheses suggested that indoor workers may have increased rates of melanoma because theyre exposed to sunlight through windows, and only UVA light, unlike UVB, can pass through window glass. At the same time, these indoor workers are missing out on exposure to the beneficial UVB rays, and have lower levels of vitamin D.

Researchers wrote: We hypothesize that one factor involves indoor exposures to UVA (321400nm) passing through windows, which can cause mutations and can break down vitamin D3 formed after outdoor UVB (290320nm) exposure, and the other factor involves low levels of cutaneous vitamin D3.

After vitamin D3 forms, melanoma cells can convert it to the hormone, 1,25-dihydroxyvitamin D3, or calcitriol, which causes growth inhibition and apoptotic cell death in vitro and in vivo.

We agree that intense, intermittent outdoor UV overexposures and sunburns initiate CMM [cutaneous malignant melanoma]; we now propose that increased UVA exposures and inadequately maintained cutaneous levels of vitamin D3 promotes CMM.

To put it simply, UVB appears to be protective against melanoma or rather, the vitamin D your body produces in response to UVB radiation is protective.

As written in The Lancet: Paradoxically, outdoor workers have a decreased risk of melanoma compared with indoor workers, suggesting that chronic sunlight exposure can have a protective effect.

Cheers Hans