Cigs, booze, obesity, smog, lack of fruit and vegetables kills millions
November 20, 2005 Edition 1
Jeremy Laurance
London - Almost 2,5 million cancer deaths worldwide could be prevented if people changed their diet and behaviour, doctors say.
Nine factors account for more than a third of the 7 million cancer deaths a year that could be avoided. Reducing smoking and alcohol intake and eating more fruit and vegetables are the most important factors, but little effort is going into promoting their life-saving effects, researchers say in the Lancet medical journal.
Scientists from the United States, Australia and New Zealand say the obsession with curing cancer has prevented progress in the war against the disease, the incidence of which is growing.
Although screening and treatment are increasingly effective in reducing the toll, their benefits are limited by cost and difficulty of access to them in many countries.
"Advances in cancer treatment have not been as effective as in other chronic diseases," they say.
"Primary prevention through lifestyle and environmental interventions remains the main way to reduce the burden of cancer."
Smoking is the biggest killer, causing 21 percent of cancer deaths worldwide. Alcohol use and low fruit and vegetable consumption are the next most lethal, each accounting for 5 percent of cancer deaths.
Other risk factors include being overweight and obesity, which account for 11 percent of colon cancer deaths and 40 percent of deaths from cancer of the uterus. Physical inactivity increases the risk of breast cancer, accounting for 10 percent of all deaths from the disease and 15 percent of colon cancer.
Low fruit and vegetable consumption is a risk factor for cancers of the oesophagus (18 percent of deaths), stomach (18 percent), colon (2 percent) and lung (11 percent).
Unsafe sex - without a condom - can transmit the papilloma virus that causes all cases of cervical cancer. Cervical cancer causes 234 000 deaths worldwide each year, more than 90 percent of them in low- and middle-income countries.
Urban air pollution, worse in the developing world, and indoor smoke from open fires and solid-fuel cookers used with inadequate ventilation increase the risk of lung cancer.
The common practice of re-using needles for medical injections in the developing world transmits hepatitis and other viruses that cause liver cancer.
Majid Ezzati, of the Harvard School of Public Health, who led the study, said: "Primary prevention through lifestyle and environmental interventions remains the main route for reducing the global cancer burden.
"Reduction of exposure to well-known behavioural and environmental risk factors would prevent a substantial proportion of deaths from cancer."
A blood test to assess risk could be available in the next decade.
Professor Karol Sikora, of Imperial College, London, and Hammersmith Hospital, said that in 20 years cancer would likely be a controllable disease.
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