Unhealthy Western ways of living are likely to fuel a massive surge in cancer rates around the world, experts have claimed.
A study predicts a more than 75% increase in the global cancer burden by 2030. In the poorest countries, the rise could be in excess of 90%.
The number of people worldwide diagnosed with cancer each year is forecast to swell from 12·7 million in 2008 to 22.2 million within the next 20 years.
The trend is blamed on the spread of Western lifestyles to developing countries, where more people are now eating convenience food, becoming obese and smoking.
A number of common cancers are linked to unhealthy high-income living, including those affecting the breast, prostate and bowel.
Substantial rises in the incidence of these diseases are likely to offset falling rates of others associated with infections, including cervical and stomach cancers, say researchers.
Scientists based their findings on a snapshot of cancer statistics collected from 184 countries in 2008.
The incidence and death rate estimates were recorded on the Globocan database compiled by the International Agency for Research on Cancer (IARC).
They showed how cancer patterns varied according to four levels of human development, measured on a Human Development Index (HDI) scale.
This information was used to project how the cancer burden was likely to change in 2030, taking into account forecasts of population size, ageing and national development.
The results are published online in the journal The Lancet Oncology.
Study leader Dr Freddie Bray, from the IARC in Lyon, France, said: "Cancer is already the leading cause of death in many high-income countries and is set to become a major cause of morbidity (illness) and mortality in the next decades in every nation of the world.
"This study serves as an important reference point in drawing attention to the need for global action to reduce the increasing burden of cancer."
Poor countries with a low HDI currently experience high rates of infection-linked cancers, such as cervical, stomach and liver cancers, and Kaposi's sarcoma.
But rich countries with a high HDI, such as the UK, US, and Australia, are more afflicted by cancers associated with smoking, obesity, diet and reproductive risk factors, such as not having children.
In both "high" and "very high" HDI regions four of these cancers - breast, lung, bowel and prostate - now account for over half the total cancer burden, the study showed.
Almost 40% of global cases of cancer in 2008 occurred in very high HDI countries, even though these regions contained just 15% of the world's population.
The research predicts medium HDI countries, such as South Africa, China and India, experiencing a 78% upsurge in cancer rates by 2030.
A 93% rise is forecast for low HDI countries, including those in sub-Saharan Africa.
Dr Christopher Wild, director of the IARC, said: "This study reveals the dynamic nature of cancer patterns in a given region of the world over time.
"Countries must take account of the specific challenges they will face and prioritise targeted interventions to combat the projected increases in cancer burden via effective primary prevention strategies, early detection, and effective treatment programmes."
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