Many people hold mistaken beliefs about what causes cancer, tending to inflate the threat from environmental factors while minimizing the hazards of personal behavior, according to a global survey released on Wednesday.

People in all countries are more ready to accept that environmental factors such as air pollution might cause cancer, than things that are within their own control such as overweight, said the survey released by the Geneva-based International Union Against Cancer (UICC).

Actually environmental factors have relatively little impact, but controllable personal behavior such as overweight or alcohol use are well established cancer risk factors, the survey said.

The survey involved interviewing 29,925 people in 29 countries across the globe during last year. It was the first study to provide internationally comparable data on perceptions about cancer risk factors.

According to the survey, people in high-income countries were the least likely to believe that drinking alcohol increases the risk of cancer.

In that group, 42 percent said alcohol does not increase the risk. That compares with only 26 percent of respondents in middle- income countries and 15 percent in low-income countries saying that alcohol use does not increase the risk of cancer.

In rich countries, stress (57 percent) and air pollution (78 percent) scored higher as perceived risk factors for cancer than did alcohol intake. In fact, stress is not recognized as a cause of cancer and air pollution is a minor contributor compared with alcohol consumption.

The survey showed that in low and middle-income countries, people were more pessimistic about the treatment and curing of cancer. In the poorest countries 48 percent felt not much could be done once the disease had taken hold.

In middle-income countries 39 percent had the same view, but in the richest countries pessimists totaled only 17 percent.

"Governments around the world will now have solid data to use to put in place education campaigns to address these beliefs and change them to save lives," said Dr David Hill, president-elect of UICC.

Hill said the UICC would use the data to push a worldwide agenda to ensure people had more accurate knowledge of cancer as a basis for making cancer control programs as effective as they can be.