Cancer will overtake heart disease as the world's number one killer by 2010 as the ‘cancer burden’ shifts from wealthy to less affluent countries. Aging populations, more smokers, increasingly fatty diets, and a lack of health care are to blame.
 | Cancer WardCancer patients in the Indian city of Kolkata on World Cancer Day February 4, 2009. The global cancer burden has shifted to poor and medium-income countries (Photo: Reuters) |
Cases Worldwide: 25 million
Main Causes: smoking, overweight and obesity, viral infection, physical inactivity, poor diet, alcohol consumption, overexposure to sunlight
Distribution: worldwide, highest prevalence in North America, Oceania and Europe
Cancer develops when damaged or mutated genes in the body’s cells divide and multiply uncontrollably forming lumps of abnormal tissue, or tumors, that stop vital organs from functioning. Malignant cancerous cells break away from the tumor and spread cancer around the body in a process called metastasis.
Cancer killed an estimated 7.6 million people in 2008, about 12 percent of all deaths worldwide. Of these deaths, more than 70 percent occurred in low- and middle-income countries, where cancer hits the poor hardest because they cannot access healthcare.
Cancer is predominantly a disease of the elderly and so the biggest reason for the rapidly increasing cancer burden is aging populations and increased life expectancy. Hence the proportion of all deaths caused by cancer varies from only 4 percent in Africa to 23 percent in North America.
But cancer is not inevitable with age. “Only 5 to 10 percent of cancers are due to inheriting high risk cancer genes,” says Cancer Research UK senior science officer Alison Ross. “About half of all cancers could be prevented by lifestyle factors.”
The biggest factor is smoking. In developed countries, where lung, breast, prostate, and colorectal cancers dominate, 25 to 30 percent of all cancers are tobacco-related. Lung cancer, rare at the beginning of the twentieth century, is now the world’s deadliest cancer for men.
 | Alison Ross, Senior Science Officer, Cancer Research UK“Only 5 to 10 percent of cancers are due to inheriting high risk cancer genes. About half of all cancers could be prevented by lifestyle factors.” |
Among non-smokers, overweight and obesity is the leading cause of cancer, while alcohol consumption, excessive exposure to sunlight, lack of physical activity, and other dietary factors are also important.
In poorer nations, stomach, liver and cervical cancers are most common, caused by chronic and viral infections. The pattern is changing, however, as developing country populations grow, age and westernize, taking up tobacco, high-fat diets, and sedentary lifestyles.
While smoking is declining in Western Europe and North America, thereby reducing underlying cancer rates, it is increasingly popular in places like China and Southeast Asia. The WHO predicts: “The Tobacco Epidemic will be driving the Cancer Epidemic in low- and medium-resource countries.”
Yet developing countries lack adequate cancer detection and treatment systems to deal with this time bomb—over 30 African and Asian countries have no radiotherapy facilities. “The rise of cancer in less affluent countries is an impending disaster,” WHO director-general Margaret Chan said last year, noting that every year 4 million cancer patients get no treatment at all.
By contrast, screening programs for breast and cervical cancer, and radiotherapy, chemotherapy, and the latest cancer drugs have increased survival rates in the rich world. In the UK, says Alison Ross, eight out of ten women diagnosed with breast cancer will live for five years or more, compared to five out of ten patients in the 1970s. An incredible 95 percent of British men diagnosed with testicular cancer will survive.
Scientists are developing drugs that isolate and destroy cancer cells, treatments that prompt the body’s immune system to attack cancerous tumors, and vaccines to prevent liver and cervical cancers. These and other scientific advances offer hope, although there will be no ‘cure for cancer’ anytime soon.
Prevention, thus, is the best option. The World Cancer Congress last year recommended 11 steps to reduce cancer worldwide by 2020. Top of the list was reducing tobacco and alcohol consumption and obesity levels. Other options to contain cancer are vaccination programs, better screening and detection, and more cancer training for healthcare workers.
editor: James Tulloch
publishing date: February 24, 2009
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