While not the most common form of cancer among human populations, pancreatic cancer still represents one of the most deadly, as the 5 year survival rate is only slightly above 7%. With few definitive associated risk factors and even fewer therapeutic interventions, understanding the underlying causes of this disease holds the key to better diagnosis and treatment options.

Now, a team of researchers from the University of California San Diego (UCSD) School of Medicine has compiled epidemiological data that suggests global pancreatic cancer rates are highest among countries with the least amount of sunlight—attributable to either higher latitudes or denser cloud cover.

“If you're living at a high latitude or in a place with a lot of heavy cloud cover, you can't make vitamin D most of the year, which results in a higher-than-normal risk of getting pancreatic cancer,” explained Cedric Garland, DrPH, adjunct professor in the Department of Family Medicine and Public Health at UCSD and lead author on the current study.

The findings from this study were published recently in the Journal of Steroid Biochemistry and Molecular Biology through an article entitled “Cloud cover-adjusted ultraviolet B irradiance and pancreatic cancer incidence in 172 countries.”

There has been evidence mounting over the past several years that implicate higher levels of vitamin D intake with reduced risk of certain cancers. Specifically, Dr. Garland and his colleagues showed previously the sufficient levels of the vitamin D metabolite, 25-hydroxyvitamin D in human serum was linked to a substantially lower risk of breast and colorectal cancer. The UCSD team believes that vitamin D levels may similarly play a major role in the development of pancreatic cancer.

“People who live in sunny countries near the equator have only one-sixth of the age-adjusted incidence rate of pancreatic cancer as those who live far from it,” said Dr. Garland. “The importance of sunlight deficiency strongly suggests—but does not prove—that vitamin D deficiency may contribute to risk of pancreatic cancer.”

The investigators looked at data from over 170 countries, accounting for international differences and possible confounders, such as alcohol consumption, obesity and smoking. After all of the information was tallied the researchers came to one conclusion.

“While these other factors also contribute to risk, the strong inverse association with cloud-cover adjusted sunlight persisted even after they were accounted for,” stated Dr. Garland.

Vitamin D is only found in a limited number of foods naturally, which is often why it is added as a fortifying nutrient to milk, cereals, and juices. However, many experts suggest that most people also require additional vitamin D to be produce by the body through direct exposure of the skin to sunlight, specifically UV-B radiation, for brief intervals of time.

Dr. Garland and his colleagues are optimistic that their findings will help in the development of improved predictors for pancreatic cancer, but are continuing their work to try and establish a molecular link between vitamin D deficiency and carcinogenesis within the pancreas. 

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