Cancer deaths are projected to more than double worldwide over the next two decades, largely from a dramatic increase in cancer incidence in low- and middle-income countries driven by tobacco use and increasingly Westernized lifestyles.A new report from the International Agency for Research on Cancer (IARC) explores the global burden of cancer, which is poised to become the leading cause of death worldwide by 2010.The report predicts that:• By 2030, 27 million new cancer cases and 17 million cancer deaths will occur each year worldwide. That compares to 12 million new cancers and slightly less than 8 million cancer deaths in 2007.• Based on current trends, the rate at which new cancers are diagnosed is expected to grow by 1% annually, as are deaths from the disease.• China, Russia, and India are projected to have the biggest increases in cancers and cancer deaths.• Smoking and other lifestyle factors like obesity will overtake chronic infection as the leading cause of cancer in poor and middle-income countries.The projections stand in striking contrast to encouraging cancer trends in the United States.A report released earlier this month showed a decline in both cancer incidence and cancer deaths for the first time in a decade. This highlights the point that the burden of cancer is shifting to less industrialized regions, IARC Director Peter Boyle, MD, tells WebMD."Forty years ago, cancer was primarily a disease of high-resource, industrialized countries," Boyle says. "That isn't true anymore. When we think of low-resource countries, we think of communicable diseases as the big killers. But each year more people across the globe die of cancer than die of AIDS, tuberculosis, and malaria combined."Cancer burden will doubleAround the world, the burden of cancer doubled between 1975 and 2000, and it is predicted to double again by 2020 and triple by 2030. Boyle notes that in 1970, just 15% of cancers occurred in poor and medium-resource countries.Today, more than half of cancer cases and two-thirds of cancer deaths occur in these underserved countries, and the disparity is expected to rise.The dramatic increase in smoking in low- and medium-income countries, which began in the mid-1980s and early 1990s, is the biggest single cause of the projected increase, which is expected to peak in 2030. It takes about 40 years for big increases in smoking rates to be reflected in smoking-related diseases like lung cancer and emphysema, Boyle says. "The big tobacco companies started to move pretty strongly into these low- and medium-resource countries in the early 1990s at about the same time that we were working very aggressively to reduce tobacco use in Western countries," he says.According to the report: • About 1.3 billion people smoke worldwide.• About 12% of cancers in low-income countries can be attributed to tobacco use, but this figure is expected to rise substantially.• Lung cancer kills more people than any other cancer worldwide. Breast cancers are also on the rise in low-income countries, where incidence rates have been increasing by up to 5% a year.And cervical cancer, which is largely preventable and treatable in the industrialized world, is a leading cause of cancer deaths among women living in poor regions, including many areas of Africa.By Salynn Boyles Reviewed by Louise Chang, MD