Low sunlight linked to increased risk of pancreatic cancer
People who live in regions that do not get a lot of sunlight are an increased risk for pancreatic cancer, possibly due to the lack of vitamin D, new research suggests.
The study, which was published online in the Journal of Steroid Biochemistry and Molecular Biology April 30, is the first to associate vitamin D deficiency with 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 study co-author Dr. Cedric Garland, an adjunct professor with the University of California, San Diego School of Medicine's Department of Family Medicine and Public Health, in a university press release.
"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 said.
He also noted that while the study strongly suggests a link between a lack of sunlight and pancreatic cancer, it does not prove that vitamin D deficiency contributes to the risk of pancreatic cancer.
While food sources of vitamin D include fatty fish such as salmon and tuna, cheese, fortified foods like milk and cereal, and egg yolks, people need more vitamin D than can be provided by good. Direct exposure to the sun increases the body's production of vitamin D.
Garland and his colleagues gathered data from 107 countries and found that countries that get the least amount of sunlight also had the highest pancreatic cancer rates. They also adjusted for other risk factors such as obesity, smoking, and alcohol consumption.
"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.
Dr. Garland and his colleagues have previously linked higher vitamin D levels to lower levels of breast and colorectal cancer, and UC San Diego researchers also previously identified an association of high latitude with a higher risk of pancreatic cancer.
According to the American Cancer Society, about 48,960 people -- 24,840 men and 24,120 women -- will be diagnosed with pancreatic cancer in 2015, and about 40,560 people (20,710 men and 19,850 women) will die of the disease.
Pancreatic cancer accounts for approximately 3 percent of all cancers in the United States and about 7 percent of cancer deaths.
According to World Cancer Research Fund International, pancreatic cancer is the 12th most common cancer in the world, with 338,000 new cases diagnosed annually. Incidence rates are highest in North America and Europe and lowest in Africa and Asia.