The developing world is expected to account for more than half of all cancer cases in the world by 2020 say medical experts.
Cancer may strike as many as 7 million people a year in Asia by 2020, straining health systems in countries that can least afford it.
Asia accounted for about half the 7 million cancer deaths worldwide in 2002, with 23 percent in China alone.
An international cancer meeting in Singapore heard that aging populations, tobacco use and increasing rates of obesity are fueling the incidence of deadly tumors in Asian countries, where patients are often too poor to afford the most advanced treatments such as Herceptin and Avastin.
According to Donald Maxwell Parkin, a senior research fellow at Oxford University in Britain, Asia already has most of the world's stomach and liver cancer cases but could well have as many as 58 percent of all cancer cases in the world by 2020, and about 65 percent of all cases by 2050.
Parkin who was speaking at the Lancet Asia Medical Forum in Singapore, says the elderly population in Asia is expected to more than quadruple by 2050.
The WHO is also warning that Asia's annual death toll from cancer, currently at about 4 million, could reach 6.4 million by 2030 if current trends continue.
By contrast says the WHO, cancer deaths in Europe, at 1.85 million in 2005, will not increase much in the next 23 years, while the yearly mortality from cancer in all the Americas may climb 40 percent to 1.64 million during the same period.
Once a disease more common in wealthy nations, experts now say cancer is increasingly afflicting developing countries due to tobacco and alcohol abuse, unhealthy diets and the lack of exercise; limited access to key cancer treatment technology in developing countries will worsen the situation.
Richard Horton, editor of the British medical journal Lancet has forecast a pandemic of cancer, the like of which has never been seen before.
Horton has questioned how the world will deal with this in view of the problems infectious diseases are currently presenting.
Researchers say cancer already kills more people worldwide than AIDS, tuberculosis and malaria combined.
In the world's two fastest -growing major economies China and India, spending to prevent and treat chronic diseases such as cancer and diabetes may slow down financial progress.
Jacques Ferlay, an informatics officer from the International Agency for Research on Cancer which is part of the World Health Organisation, says about 30 African and Asian countries currently have no access to radiotherapy services.
Ferlay says tobacco abuse is expected to cause one billion deaths in the world in the 21st century, 10 times the number of deaths it was estimated to have caused in the 20th century.
The cost in the UK to treat a breast cancer patient with Herceptin is around $50,000; in comparison, per capita government expenditure on health in 2003, according to the WHO, was $4 in Bangladesh, $7 in India, $11 in Indonesia and $22 in China in 2003, according to the WHO.
According to the WHO's 2006 World Health Report, as many as 1.1 million doctors and nurses are urgently needed in Southeast Asia alone, where shortages of health-care workers exist in six of the region's 11 countries.