Cloud cover-adjusted ultraviolet B irradiance and pancreatic cancer incidence in 172 countries

Background: Controversy exists regarding whether vitamin D deficiency could influence the etiology of pancreatic cancer. Several cohort studies have found that high serum 25-hydroxyvitamin D [25(OH)D] concentrations are associated with low risk of pancreatic cancer, while others have not. Hypothesis: Low ultraviolet B irradiance is associated with high incidence of pancreatic cancer. Methods: Age-standardized pancreatic cancer incidence rates were obtained from GLOBOCAN in 2008. The association between cloud-adjusted UVB irradiance and age-standardized incidence rates of pancreatic cancer was analyzed using regression. Results: Overall, the lower the cloud-adjusted UVB irradiance, the higher the incidence rate of pancreatic cancer. Residents of countries with low UVB irradiance had approximately 6 times the incidence rates as those in countries with high UVB irradiance (p < 0.0001 for males and p < 0.0001 for females). This association persisted after adjustment for traditional risk factors of pancreatic cancer (p = 0.0182 for males and p = 0.0029 for females). Conclusions: There was an inverse association of cloud-adjusted UVB irradiance with incidence of pancreatic cancer that persisted after adjustment. This result is consistent with an inverse association of overall vitamin D deficiency in countries with lower UVB irradiance with risk of pancreatic cancer. Further research on the role of 25(OH)D in reduction of pancreatic cancer in individuals would be desirable to expand the limited avenues available for prevention of this highly fatal disease. This article is part of a Special Issue entitled '17th Vitamin D Workshop'. (C) 2015 Elsevier Ltd. All rights reserved.