Many people hold mistaken beliefs about what causes cancer, tending to inflate the threat from environmental factors that have relatively little impact while minimising the hazards of behaviours well established as cancer risk factors, according to the first global survey on the topic.
The survey identified key areas where misconceptions could be addressed and where lives could be saved. It involved interviewing 29,925 people in 29 countries across the globe during the last year.
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 high-income countries, the hazards of not eating enough fruits and vegetables scored more highly as a perceived risk than alcohol intake did, 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 and air pollution scored higher as perceived risk factors for cancer than did alcohol intake. However, stress is not recognised 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.
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% 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.
Dr David Hill, President-Elect of UICC and director of the Cancer Council Victoria in Melbourne, Australia, whose team analysed 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.