Objectives: To examine whether past and recent sun exposure and vitamin D status (serum 25-hydroxyvitamin D [25(OH)D] levels) are associated with risk of first demyelinating events (FDEs) and to evaluate the contribution of these factors to the latitudinal gradient in FDE incidence in Australia. Methods: This was a multicenter incident case-control study. Cases (n = 216) were aged 18–59 years with a FDE and resident within one of 4 Australian centers (from latitudes 27°S to 43°S), from November 1, 2003, to December 31, 2006. Controls (n = 395) were matched to cases on age, sex, and study region, without CNS demyelination. Exposures measured included self-reported sun exposure by life stage, objective measures of skin phenotype and actinic damage, and vitamin D status. Results: Higher levels of past, recent, and accumulated leisure-time sun exposure were each associated with reduced risk of FDE, e.g., accumulated leisure-time sun exposure (age 6 years to current), adjusted odds ratio (AOR) = 0.70 (95% confidence interval [CI] 0.53–0.94) for each ultraviolet (UV) dose increment of 1,000 kJ/m² (range 508–6,397 kJ/m²). Higher actinic skin damage (AOR = 0.39 [95% CI 0.17–0.92], highest grade vs the lowest) and higher serum vitamin D status (AOR = 0.93 [95% CI 0.86–1.00] per 10 nmol/L increase in 25(OH)D) were independently associated with decreased FDE risk. Differences in leisure-time sun exposure, serum 25(OH)D level, and skin type additively accounted for a 32.4% increase in FDE incidence from the low to high latitude regions. Conclusions: Sun exposure and vitamin D status may have independent roles in the risk of CNS demyelination. Both will need to be evaluated in clinical trials for multiple sclerosis prevention.

Primary liver cancer, the most common histologic types of which are hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC), is the second leading cause of cancer death worldwide. While rising incidence of liver cancer in low‐risk areas and decreasing incidence in some high‐risk areas has been reported, trends have not been thoroughly explored by country or by histologic type. We examined liver cancer incidence overall and by histology by calendar time and birth cohort for selected countries between 1978 and 2007. For each successive 5‐year period, age‐standardized incidence rates were calculated from volumes V‐IX of the Cancer Incidence in Five Continents electronic database (CI5plus) and the newly released CI5X (volume X) database. Wide global variations persist in liver cancer incidence. Rates of liver cancer remain highest in Asian countries, specifically Eastern and South‐Eastern Asian countries. While rates in most of these high‐risk countries have been decreasing in recent years, rates in India and several low‐risk countries of Africa, Europe, the Americas, and Oceania have been on the rise. Liver cancer rates by histologic type tend to convey a similar temporal profile. However, in Thailand, France, and Italy, ICC rates have increased while HCC rates have declined. We expect rates in high‐risk countries to continue to decrease, as the population seroprevalence of hepatitis B virus (HBV) continues to decline. In low‐risk countries, targeted screening and treatment of the hepatitis C virus (HCV), treatment of diabetes and primary prevention of obesity, will be key in reducing future liver cancer incidence.