Pancreatic cancer rates higher in countries with less sunlight

Brett Smith for redOrbit.com – @ParkstBrett

Those of us living in northern latitudes know that not getting enough sunlight during winter can have a negative effect on our mood, and now it turns out those grey skies could also mean a higher risk of pancreatic cancer.

According to a new study published in the Journal of Steroid Biochemistry and Molecular Biology, countries with the lowest levels of sunlight year-round, due to either cloud cover or latitude, have the highest incidences of pancreatic cancer. The study team suggested that the effect could be due to lower levels of vitamin D.

“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 study author Cedric F. Garland, adjunct professor in the Department of Family Medicine and Public Health at the University of California, San Diego.

“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,” Garland added. “The importance of sunlight deficiency strongly suggests – but does not prove – that vitamin D deficiency may contribute to risk of pancreatic cancer.”

Strengthening the connection

Previous work by the same researchers had revealed that adequate levels of a metabolite of vitamin D, known as 25-hydroxyvitamin D, was connected with considerably reduced risk of breast and colorectal cancer. In the new study, scientists studied information from nearly 110 countries, taking into consideration relevant international difference and confounding factors, such as alcohol usage, 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,” Garland said.

Past research has made the connection between high latitude and a greater risk of pancreatic cancer before; however, Garland said the new study strengthens that connection by looking at levels of solar ultraviolet B radiation adjusted for cloud cover.

The study team noted that their paper is the first to point directly to vitamin D deficiency with respect to pancreatic cancer risk. In addition to sunlight, vitamin D can also be obtained by eating fatty fish, cheese, and egg yolks.

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