GENEVA, Switzerland – Many people hold mistaken beliefs about what causes cancer, tending to inflate the threat from environmental factors that have relatively little impact while minimizing the hazards of behaviours well established as cancer risk factors, according to the first global survey on the topic.
The survey, conducted by Roy Morgan Research and Gallup International on behalf of the International Union of Against Cancer (UICC), identified key areas where misconceptions could be addressed and where lives could be saved.
The survey involved interviewing 29,925 people in 29 countries across the globe during the last year. It is the first study to provide internationally comparable data on perceptions about cancer risk factors. The results, which allow for comparison between high-, middle- and low-income countries, were released Wednesday at the UICC's World Cancer Congress in Geneva.
Key findings from the survey include:
- People in high-income countries were the least likely to believe that drinking alcohol increases the risk of cancer. In that group, 42% said alcohol does not increase the risk. That compares with only 26% of respondents in middle-income countries and 15% in low-income countries saying that alcohol use does not increase the risk of cancer. In fact, cancer risk rises as alcohol intake increases.
- In high-income countries, the hazards of not eating enough fruits and vegetables scored more highly as a perceived risk (59%) than alcohol intake did (51%), even though the scientific evidence for the protective effect of fruit and vegetables is weaker than the evidence that alcohol intake is harmful.
- In rich countries, stress (57%) and air pollution (78%) scored higher as perceived risk factors for cancer than did alcohol intake. However, stress is not recognized as a cause of cancer and air pollution is a minor contributor compared with alcohol consumption.
- People in low- and middle-income countries have more pessimistic beliefs about cancer treatment than those in high-income countries. One of the more important problematic beliefs in lower-income countries concerned perceptions about the curability of cancer. The survey found that in such countries 48% said that "not much can be done" to cure cancer or that they didn't know whether anything could be done. That compares with 39% in middle-income countries and 17% in high-income countries. Such a misbelief is worrying because it might deter people from participating in cancer screening programmes, which are important for saving lives.
- In general, people in all countries are more ready to accept that things outside of their control might cause cancer (such as air pollution), than things that are within their own control (such as overweight, which is a well-established cancer risk factor).
- An astonishing 75% percent of people in low-income countries said their preference was for their doctor to make all the treatment decisions. Only 8% said the doctor and patient should decide together and 9% said the patient should decide. That compares with a preference in rich countries for a more equitable decision-making style that emphasises self-determination, with 72% saying either that the decision should be made together or rest with the patient alone.
Dr David Hill, President-Elect of UICC and director of the Cancer Council Victoria in Melbourne, Australia, whose team analyzed the survey data, said 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.
"The survey reveals there are some big unheard messages. These kind of data help us to quantify the differences between countries and to highlight where additional efforts are needed. Some of these countries have rarely had any population survey data to help their programme planning efforts," he said.
"We know that people need to be given a reason why they should change. They need to be shown how to change; they need to be given resources or support to change; they need to remember to change and they need positive reinforcement for changing. Many of these principles can be applied in designing education programmes to encourage and support behaviour change," he said.
Dr 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 programmes as effective as they can be.