Cancer, Vitamin D, Sunlight

Well here is a quandary.
In the last entry I talked about Vitamin D.
And now they are studying the link between sunlight causing or maybe preventing certain cancers and diseases.
Of course radiation causes cancer, but it can also be used to treat cancer.

"Since vitamin D has been shown to play a protective role in a number of internal cancers and possibly a range of other diseases, it is important to study the relative risks to determine whether advice to avoid sun exposure may be causing more harm than good in some populations," Setlow warned.
http://www.guardian.co.uk/science/2009/feb/08/vitamin-d-sun-health

And here's another article:
Doesn't sunlight cause cancer?
Yes, long-term exposure to ultraviolet radiation from the sun (UVA and UVB) has been shown to increase the risk of skin cancer. This is why it is recommended that we wear sunscreen and sun-protective clothing during the summer months.

How can sunlight also protect against cancer?
The answer lies in a vitamin that may play a role in controlling the production of cells - vitamin D. Vitamin D is manfactured in the skin when it is exposed to sunlight and it is this vitamin that may have a protective effect against certain cancers by preventing the overproduction of cells.
http://www.bupa.co.uk/health_information/html/health_news/261103vitd.html