Poor Sunlight Exposure Linked to Pancreatic Cancer, Research Finds

Lisa Franchi May 07, 2015

Researchers from the University of California San Diego School of Medicine report pancreatic cancer rates are highest in countries with the least amount of sunlight.

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

The study, published in the Journal of Steroid Biochemistry and Molecular Biology, suggests that people who live in sunny countries near the equator have only one-sixth of the age-adjusted rate of pancreatic cancer, as compared with 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." Says Cedric F. Garland, DrPH, adjunct professor in the Department of Family Medicine and Public Health and member of UC San Diego Moores Cancer Centre.

"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,"

The UC San Diego team, led by Garland and Edward D. Gorham, PhD, associate professor, had previously shown 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. The current paper is the first to implicate vitamin D deficiency with pancreatic cancer.

The main and largest source of vitamin D remains to be the sunlight. This important vitamin is present in some foods as well, but only in a limited amount. They include egg, beef liver, cheese, fatty fish and fortified meals.

Researchers say that skin exposed to sunshine indoors through a window will not produce vitamin D. furthermore, cloudy skies, shade and dark-coloured skin also reduce vitamin D production.

For the study, researchers gathered 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," said Garland.

In previous studies, the research team 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.

Source of this article: Pancreatic Cancer Risk Linked to Weak Sunlight