Cancer has been part of human history for millennia, as has misinformation about its causes and cures. From ancient theories about black bile and humours, to modern misinformation about miracle foods or biohacking (self-experimentation to optimise health), misinformation about cancer has continually evolved to reflect the concerns of its time.
Today, however, technology means that the speed and scale at which misinformation can spread is virtually limitless. Online platforms are designed to prioritise content that captures attention and generates engagement – meaning emotionally charged, simplistic or sensational claims can often travel further than evidence-based information.
Research suggests misinformation spreads particularly effectively when it taps into fear, hope, personal identity or distrust. This is especially concerning in the context of health, where misleading advice can influence decisions about modifiable behaviours that impact health outcomes including cancer.
A brief history of cancer prevention research
The relationship between diet and cancer has been debated for centuries. In the 1800s, researchers began exploring and discussing these associations, but it was not until the 1970-1980s that major organisations held conferences and produced reports evaluating the evidence in a systematic way. The results of early studies were often greeted with high levels of disagreement, and sometimes hostility, from those working in the cancer field and food industry.
This may partly explain why research exploring modifiable risk factors and cancer stalled, only gaining traction towards the end of the 20th century. It was at this time that scientists began to explore which cancers could be prevented if individuals were to follow public health recommendations for cancer prevention.
While early estimates suggested that 75-80% of cancers in the United States could be prevented by changes in modifiable risk factors, at the time the focus was on diet. After decades of research, today, it is estimated that approximately 40% of cancer cases are preventable – with smoking, diet, excess bodyweight, physical inactivity, alcohol consumption, and avoiding UV exposure among the main contributors.
Although these messages may sound simple, they are grounded in evidence that has been rigorously reviewed, challenged and interpreted by experts around the world. This scientific rigour is one of the greatest tools we have to counter the rise in misinformation.
The role of WCRF
The World Cancer Research Fund Network has played a central role in building the current scientific evidence-base. In 1997 we published the first major report synthesising the available evidence on how diet, nutrition and other modifiable behaviours affect cancer risk.
Over the following two decades, we produced further landmark reports, including the 2018 Third Expert Report, ‘Diet, Nutrition, Physical Activity and Cancer: a Global Perspective’.
This major body of work examined the relationships between food, alcohol, bodyweight, physical activity and the risk of 17 cancers. The report also expanded the focus to people living with and beyond cancer. The results formed the scientific basis for World Cancer Research Fund International’s Cancer Prevention Recommendations, which translate complex evidence into practical public guidance.
Exploring emerging evidence
Scientific evidence does not stand still. In 2006, World Cancer Research Fund International established what is now known as the Global Cancer Update Programme (CUP Global).
Today, CUP Global includes the largest global cancer prevention and survivorship database in the world, containing more than 12,000 publications. Independent researchers systematically review the latest evidence, while an expert panel interprets the findings to ensure our Recommendations remain grounded in the most up-to-date science.
In 2022, CUP Global evolved to take a broader and more strategic view of cancer prevention. Alongside diet, nutrition, physical activity and body weight, it now explores emerging areas of investigation including ultra-processed foods, sugary drinks, sedentary behaviour, early-life exposures, and life after a cancer diagnosis. A further focus is dietary and lifestyle patterns, indicating the importance of looking at what people do across the lifecourse, rather than a single food or behaviour.
Advice grounded in science
To counter misinformation, we must try to understand the social and psychological forces behind it. Research led by Alex Ruani – a health misinformation expert at University College London – has highlighted how modern health misinformation is often not entirely false. Instead, it may contain partial truths, missing context, exaggerated claims or misleading interpretations of scientific findings.
Experts have warned that repeated exposure to misleading health claims can gradually erode trust in evidence-based guidance and make it harder for people to know what or who to trust. At the same time, scientists and public health experts are increasingly concerned about the volume of misleading diet and health content circulating across social media, search platforms and AI-generated summaries.
A new chapter in an old story
Cancer misinformation is nothing new – but the channels carrying them are. Where once a misleading claim might travel by word of mouth or a single newspaper column, today it can reach millions in hours. Black bile and miracle cures have simply been replaced by viral videos, wellness influencers and AI-generated “facts” that blur the line between evidence and opinion.
We know 40% of cancers are preventable because of decades of research by experts around the world. But evidence alone is not enough. If misinformation is shaping the decisions people make about their bodies, their food and their futures, then countering misinformation becomes a core issue for the cancer prevention community. Over the next three years, beginning with World Cancer Research Fund’s ‘Science not fiction’ Cancer Prevention Action Week (15–21 June), we will work to expose how misinformation spreads, equip people to recognise it, and put trustworthy, evidence-based guidance back at the centre of the conversation.
We invite leaders across healthcare, public health and research to join us in ensuring that science, not fiction, shapes how cancer risk is reduced globally.
Authors
Vanessa Gordon-Dseagu
Vanessa is the Research Translation Manager at World Cancer Research Fund International. Her current role is focussed on translating the research within CUP Global into outputs for the public, researchers and policymakers. She received her PhD from University College London and has extensive experience working in cancer epidemiology, as well as health policy. Vanessa has worked for several academic and research institutions, including the National Cancer Institute (NCI) in the U.S, Cancer Research UK and UCL.
Lilly Matson
Lilly is the Campaign Manager at World Cancer Research Fund International, where she focusses on communicating science and policy news with the general public. She has a Masters in Science Communication from Imperial College London and has worked in translating science across research organisations including Cancer Research UK, The Royal Society of Tropical Medicine and Hygiene and The University of New South Wales, Sydney.
Declarations of Interest
No interests to disclose.