They incorrectly identify stress, food additives, genetically modified foods, and electromagnetic fields as causes.
They have poor awareness of a number of known cancer risk factors, such as obesity, and eating red or processed meat or drinking alcohol, according to a Cancer Research UK-funded study.
Experts from University College London (UCL) and the University of Leeds said that the public’s endorsement of mythical cancer causes has risen over the last decade, possibly due to changes in the way people access information through social media and the internet.
Researchers surveyed 1,330 people.
Participants were asked how much they agreed that items on a list — including known risk factors and “mythical” factors — can increase a person’s chance of developing cancer.
The study, published in the European Journal of Cancer, found that a quarter of people incorrectly believed that using a mobile phone was a risk factor for cancer, while more than two in five people think stress or food additives may increase their risk.
More than a third (35%) incorrectly said that electromagnetic frequencies were a risk factor, while three in 10 falsely believe that living near power lines could be.
Aerosols, cleaning products, and artificial sweeteners were all also incorrectly identified as cancer risk factors.
Meanwhile, people also failed to identify known risk factors, including drinking alcohol, not getting enough fruit and vegetables, low levels of physical activity, and being over the age of 70.
Two in five failed to identify being overweight or obese as a cancer risk factor.
“Obesity was also poorly recognised, which is concerning, considering it is the second leading preventable cause of cancer,” the authors wrote.
Dr Samuel Smith, from the University of Leeds, said: “It’s worrying to see so many people endorse risk factors for which there is no convincing evidence. Compared to past research, it appears the number of people believing in unproven causes of cancer has increased since the start of the century, which could be a result of changes to how we access news and information, through the internet and social media.
“It’s vital to improve public education about the causes of cancer, if we want to help people make informed decisions about their lives and ensure they aren’t worrying unnecessarily.”
UCL’s Dr Lion Shahab added: “People’s beliefs are so important, because they have an impact on the lifestyle choices they make. Those with better awareness of proven causes of cancer were more likely not to smoke and to eat more fruit and vegetables.”
Clare Hyde, from Cancer Research UK, said: “Around four in 10 cancer cases could be prevented through lifestyle changes, so it’s crucial we have the right information to help us separate the wheat from the chaff.
“Smoking, being overweight, and over-exposure to UV radiation from the sun and sunbeds are the biggest preventable causes of cancer.
There is no guarantee against getting cancer, but by knowing the biggest risk factors, we can stack the odds in our favour to help reduce our individual risk of the disease, rather than wasting time worrying about fake news.