Researchers are reporting that pancreatic cancer rates are highest in countries with the least amount of sunlight, due to a combination of heavy cloud cover and high latitude. 

More papers showing Vitamin D is both cause and cure for numerous things is taking mainstream media by storm. Vitamin D is important, of course, and sunlight is an important source of it, though some foods also have it. Fatty fish, such as salmon and tuna, are good sources, while beef liver, cheese and egg yolks provide small amounts. Because it is not common in food it is often added as a fortifying nutrient to milk, cereals and juices.

Pancreatic cancer is the 12th most common cancer in the world, according to World Cancer Research Fund International, with 338,000 new cases diagnosed annually. Incidence rates are highest in North America and Europe; lowest in Africa and Asia. It is the seventh most common cause of death from cancer. 

Global incidence rates of pancreatic cancer (per 100,000) and ultraviolet B radiation (watts per square meter). Credit: UC San Diego School of Medicine

A new paper has linked Vitamin D to pancreatic cancer. The authors had previously found that sufficient levels of a metabolite of vitamin D in the serum, known as 25-hydroxyvitamin D was associated with substantially lower risk of breast and colorectal cancer. Their current paper is the first to implicate vitamin D deficiency with pancreatic cancer. 

Researchers studied data from 107 countries, taking into account international differences and possible confounders, such as alcohol consumption, obesity and smoking. "While these other factors also contribute to risk, the strong inverse association with cloud-cover adjusted sunlight persisted even after they were accounted for. Researchers had previously identified an association of high latitude with a higher risk of pancreatic cancer. Garland said the new study advances that finding by showing that an estimate of solar ultraviolet B that has been adjusted for heavy cloud cover produces an even stronger prediction of risk of pancreatic cancer.

"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," said first author Cedric F. Garland, DrPH, adjunct professor in the Department of Family Medicine and Public Health and member of UC San Diego Moores Cancer Center. "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. The importance of sunlight deficiency strongly suggests - but does not prove - that vitamin D deficiency may contribute to risk of pancreatic cancer."

Published in the Journal of Steroid Biochemistry and Molecular Biology. Coauthors of the study include Raphael E. Cuomo, Kenneth Zeng and Sharif B. Mohr, all at UC San Diego. Funding for this research came, in part, from UC San Diego Department of Family Medicine and Public Health.