Vitamin D & Cancer- Could it be just sunlight, and not Vitamin D?

New studies funded by NCI have checked out whether people with high circulating levels of Vitamin D have lower rates of certain rare cancers, and have come up with zilch. Vitamin D doesn't seem to be related to incidence of those cancers. For example, non-hodgkins lymphoma: not affected by Vitamin D. But, Non-hodgkins lymphoma IS inversely related to sun exposure. So, the authors of that study (available free-click here) speculate that there may be some other effect of sunlight on immune systems, not acting through Vitamin D, which protects against n-h lymphoma. Could such an effect be making Vitamin D look good across a variety of correlational studies? Maybe... we'll have to stay tuned to the research as it emerges.