The number of smokers in Africa continues to grow despite a global decrease. Credit: Media Lens King/Alamy China — a country where more than 40% of men smoke — has become the epicentre of the global lung cancer epidemic. Historically, lung cancer has been predominantly a disease of rich industrialized nations. But the burden of disease in China is indicative of a global shift, with middle-income countries facing the greatest increase in cases as high rates of smoking combine with rapid population growth, urbanization and the associated air pollution. The trend is most dramatic in upper-middle-income countries, as defined by the World Bank, including China, Brazil and Iran.…