Does solar exposure, as indicated by the non-melanoma skin cancers, protect from solid cancers: Vitamin D as a possible explanation

Correlational study

Link: http://www.ejcancer.com/article/S0959-8049%2807%2900324-3/abstract

From conclusions:

"Vitamin D production in the skin seems to decrease the risk of several solid cancers (especially stomach, colorectal, liver and gallbladder, pancreas, lung, female breast, prostate, bladder and kidney cancers)."