• 11/20/2005
  • London, England
  • James Meikle
  • Sydney Morning Herald (www.smh.com.au)

More than a third of cancer deaths worldwide have preventable causes that could be tackled by changing people’s behaviour and environment, a study has found.

The impact of smoking on several cancers is well known, but alcohol use, unsafe sex, low fruit and vegetable intake, obesity, lack of exercise, contaminated injections and indoor smoke from fuels are also risks that could be reduced.

Majid Ezzati, of the Harvard School of Public Health in Boston, and colleagues suggest in the medical journal The Lancet that health interventions could prevent a “substantial proportion” of the 7 million cancer deaths a year, and be more effective in reducing mortality than screening and ever-improving treatments.

Smoking is a factor in 21 per cent of all cancer deaths, especially in men, they say, with alcohol and low fruit and vegetable intake accounting for 5 per cent each. Sexual transmission of the human papilloma virus is a leading risk factor for cervical cancer in low- and middle-income countries, especially where screening is limited, although there are hopes that vaccines will soon be widely available.

The researchers say smoking is linked to deaths from lung, bronchial and tracheal cancers, oesophageal cancers and oral cancers. Oesophageal cancer deaths and oral cancer deaths are also linked to alcohol. They based their figures on a review of published studies, government reports and international databases, as well as a reanalysis of primary data. Problems with missing information meant they did not include other factors such as occupational risk or exposure to ultraviolet light and passive smoking.

Meanwhile, Karol Sikora from Imperial College and Hammersmith hospital in London predicted that in 20 years “we will be talking about controlling cancer in the long term, not eradicating it but making cancer like diabetes”. Improving technology allowed more personalised and targeted treatments. For instance, improvements in imaging equipment provided better pictures of the location of tumours to direct radiotherapy.

Globally, however, health services would struggle to pay for new treatments and prevention programs as the number of people diagnosed with cancer continued to grow. “We will not eliminate cancer in the next 25 to 50 years,” Professor Sikora said. “That is not possible. Even if everyone stopped smoking tomorrow there would still be cancer in 2025.”

He said a blood test to predict a person’s risk of developing cancer may be possible in 10 years. That could help to make people more motivated to make lifestyle changes, he told a conference organised by the charity Canceractive.

Professor Mike Richards, Britain’s national cancer director, said the incidence of the disease was continuing to rise because the population was growing older. “One in four people are dying of cancer and that is likely to go on for some while longer. If you look at the death rate for cancer, it is going down, but not fast enough.”