Four out of 10 people surveyed did not know that being overweight is linked with an increased risk of cancer, according to new research.
Three out of four were unaware that a diet with fewer than five portions of fruit or vegetables a day raises the risk of getting the disease.
The figures emerged from a survey of 1,327 adults exploring the publics understanding of the lifestyle-risk factors linked to cancer.
It is estimated that a third to half of all cancers are preventable... If people are to make decisions about reducing their risks they need an accurate understanding of what those risks are.
Dr Sam Smith
Researchers at the University of Leeds and University College London have revealed widespread levels of confusion over the risk factors. Some people were ignorant of the proven risk factors: others held 'mythical' beliefs, blaming factors despite the study indicating a lack of any good evidence linking them with cancer.
The findings are published in the European Journal of Cancer.
Dr Sam Smith, joint lead author and University Academic Fellow at the Leeds Institute of Health Sciences, said: It is estimated that a third to half of all cancers are preventable through life style changes. That means there are more than one million avoidable cancers per year in Europe alone.
If people are to make decisions about reducing their risks of cancer they need an accurate understanding of what those risks are. Our survey shows that there is a large degree of confusion among the general public regarding those risks.
Failing to understand proven lifestyle risks
The study analysed data from the Attitudes and Beliefs About Cancer-UK Survey conducted in 2016.
The findings identifying a lack of awareness of the risks around poor diet and obesity have also been observed in other European countries. The authors in this study argue that obesity is the second-leading preventable cancer cause and more needs to be done to explain the role of weight in cancer development.
The analysis also showed that four out of 10 respondents were not aware of the risks of sunburn. Slightly more than six out of 10 respondents (65 per cent) were not aware that doing less than 30 minutes of moderate physical activity five times a week increased the risks.
The survey revealed that better knowledge of the actual causes of cancer was more likely to be found among respondents who had post-16 education qualifications.
'Mythical' causes of cancer
The survey also revealed misplaced concerns about factors where there was no good evidence to suggest they were linked to cancer. Almost half of the respondents (42 per cent) thought stress was a risk factor with a quarter thinking that the use of a mobile phone could cause cancer (26 per cent) as would the consumption of food additives.
Just under one third (30 per cent) believed living in close proximity to power lines or eating genetically-modified foods was potentially carcinogenic.
People who endorsed the cancer 'myths' were more likely to be white, younger, smokers or former smokers, and from the North of England, the data showed.
Public health challenge
Dr Smith said: While public knowledge of cancer is improving, this survey shows more needs to be done to ensure messages about cancer risk are communicated effectively.
Improving public understanding of cancer should be prioritised if we are to improve our efforts to prevent cancer.
The researchers say the numbers of people who believe in the unfounded causes of cancer has increased over the last decade, and they speculate that might be linked to the way people now get their news and information.
The authors believe public confusion over the causes of cancer could stem from the way some small-scale research projects which suggest possible causes of cancer get over hyped in the media.
Dr Lion Shahab, joint lead author from University College London, said: The concern with a substantial proportion of the population endorsing cancer myths is that this may lead them to ignore the actual causes of cancer.
This may result in people changing behaviours, for instance not eating genetically-modified foods, which are unlikely to have a positive health impact while not changing behaviours that we know can prevent cancer such as eating sufficient fruit and vegetables per day.
Journalists with questions or interview requests should contact the University of Leeds press office on 0113 343 4031 or email firstname.lastname@example.org