Cancer falsehoods and rumors are killing people
False hope, online incentive structures, and broken trust make cancer misinformation so hard to stop.
Every week, we ask you, the YLE community, what’s on your mind. Every week, we get questions about cancer and [fill-in-the-blank] prevention, cure, or treatment. It’s a game of whack-a-mole, but there’s an important thread across all of them. So, I asked Dr. Matthew Facciani–a misinformation researcher at Yale–to chime in. Matt, take it away.
Most online rumors or falsehoods do their damage slowly: polarization, eroded trust, and fractured public discourse. But there is one corner of the landscape where the consequences are immediate, and far easier to measure: cancer. That matters enormously for patients themselves, but it also gives us the clearest case study of why bad health information spreads so well—and what actually stops it.
Why cancer is uniquely vulnerable
A cancer treatment decision is about as high-consequence as a health decision gets, but features of the disease make it unusually prone to a confusing and ultimately dangerous information environment:
Cancer is extraordinarily complex. The word covers hundreds of distinct diseases and thousands of treatment options, and clinical practice guidelines grew exponentially in length between 1996 and 2019. In addition, what causes cancer is a complex combination of genetics, environment, and chance. This complexity is fertile ground for confident, simple-sounding answers.
Most cruelly, the diagnosis itself disarms the patient. Psychological distress, fatigue, and information overload are common and can cloud cognitive reserves. The patients who most need to make careful decisions are overburdened when it’s time to decide.
Recommended treatments often have terrible and sometimes lifelong side effects. Alternatives to surgeries, hair loss, nausea, fatigue, weight change and other serious side effects can certainly sound appealing. Cancer patients are in a desperate catch-22 between cancer and awful treatments.
There’s money in exploiting it. The U.S. alternative medicine industry was estimated at $30 billion in 2022. This creates strong economic motives to target desperate patients with familiar-sounding, out-of-pocket “cures” like high-dose vitamins, supplements, or rigid diets.
And the exposure to falsehoods isn’t limited to people who already have cancer. Screening and vaccination are decisions healthy people make (in the same noisy environment, often with less urgency to get them right), so the vulnerability starts well before any diagnosis.
Falsehoods and rumors take advantage of this environment and cause measurable harm. Cancer is a model topic for studying falsehoods and rumors precisely because its consequences are so measurable. Unlike political misinformation, where real-world effects are diffuse and harder to trace, cancer falsehoods produce outcomes we can track more directly: treatment adherence, survival rates, mortality.
A 2018 study found that cancer patients who chose alternative treatments over conventional ones were more than twice as likely to die within five years. For colorectal and breast cancer, the risk was 4.5 and 5.6 times greater (or a 350% and 460% increase in the risk of death, respectively). That matters because cancer is the second leading cause of death, and 40% of people will be diagnosed in their lifetime.
The algorithm and identity challenge
Across YouTube, TikTok, Instagram, and Twitter, low-quality content gets more views, more likes, and more shares than accurate content. A 2024 review documented just how thoroughly falsehoods have saturated the cancer information environment. One study found that inaccurate cancer articles were 28 times more likely to be shared than factual ones. The reason is structural: algorithms reward engagement, and fear, hope, and outrage drive engagement far more reliably than careful, evidence-based communication.
But flooding the zone with better information fails, and for a deeper reason: identity. Once a belief attaches to an important social identity (an anti-establishment worldview, distrust of pharma, a community of fellow patients seeking alternatives), challenging it stops feeling like a factual dispute and starts feeling like a personal attack. People dig in.
A diagnosis is itself a profound identity disruption, and alternative treatment communities offer something oncology waiting rooms often cannot: belonging, agency, and hope. The social and psychological rewards of those communities are real, even when the medical claims are false.
A new study shows the mechanism in real time. After a viral podcast episode in which celebrities promoted ivermectin and fenbendazole as off-label cancer treatments, prescribing rates doubled overall and rose more than 2.5 times among cancer patients specifically, across nearly 70 million patient records nationwide. The sharpest increases were among white patients, men, and Southern residents, mirroring the demographic profile of the platforms promoting the claims. Causality is hard to parse here. We cannot say whether the podcast drove the prescriptions or tracked an online conversation already growing. But, the falsehoods didn’t spread randomly. They traveled through identity-aligned networks already primed to receive it. The same communities that promoted ivermectin for Covid-19 later promoted it for cancer. The claim changed; the underlying identity orientation did not.
The same dynamic shapes prevention falsehoods, too. Vaccine-skeptical networks spread HPV vaccine claims through the same identity-based channels, even if the specific communities involved are different.
What would actually help
Cancer rumors are a textbook case of false empowerment: compelling precisely because they speak to people living in fear. There’s no single fix, but the research points to a few things:
1. Train clinical care teams to address falsehoods. Just 18% of physicians report any formal training in addressing unproven treatments, even though 99% of oncology practitioners encounter it regularly. Care teams need the communication skills to correct falsehoods and do so without making the patient feel attacked. The goal is to connect with what the patient values first, then address the belief.
2. Prebunk before patients go searching. Don’t wait for a bad claim to return to the exam room. Warn patients or family members in advance about what cancer myths look like, and give them one simple tell: if someone is selling you a cure, be skeptical. Clinics offering unproven treatments spent an estimated $15.8 million on Google Ads targeting cancer patients’ search queries between 2012 and 2023. A short heads-up beforehand beats a correction afterward.
3. Empower patients, do not just correct them. Alternative communities offer belonging, agency, and hope. Instead of only stripping out the false version, supply the real one: a trusted relationship and the skills to evaluate what patients find on their own. Strong health and media literacy skills, along with high trust in science, are among the most consistent protections against health falsehoods. Give people agency and a trusted place to bring their questions.
4. Support the infrastructure around trusted messengers. We do not fix a fractured information environment by broadcasting more facts into the noise alone. The trusted messengers (the doctor who listens before prescribing, the community figure who knows the family) work because they are in a relationship with the people they serve. But asking trusted messengers to show up and respond to myths and bad information only works if we support them. Many want to, but they run into real barriers: insufficient training, lack of time, online harassment, and limited institutional support. The fix is engagement training plus institutional backing that provides resources and infrastructure to do so.
5. Meet people where they are. It’s important to be present on social media, podcasts, and other digital platforms where patients often seek answers. Corrections from credible experts do reduce false beliefs, and the people quietly watching the exchange are often the ones who update. Even publishing in more traditional venues, such as university websites and major newspapers, has real value. AI companies are paying to train on high-quality journalism, and AI search tools disproportionately rely on authoritative institutional sources, especially for health questions.
We can also direct patients to evidence-based complementary approaches that may help them feel empowered alongside conventional treatment, as well as support them physiologically.
Bottom line
Cancer falsehoods online are directly linked to higher rates of death, yet we still treat them as something for individual patients to navigate and individual doctors to address in brief appointments, while platforms continue doing the opposite. It’s the clearest example of a lesson that reaches far beyond health: when trust breaks down, misinformation need not be convincing; it only needs to be available. Building resilience means creating the social conditions where trusted people shape our most important decisions.
Sincerely, MF
Big thank you to Dr. Andrea Betts, a cancer researcher expert, for her input and edits on this post.
Dr. Matthew Facciani is a social scientist and researcher at the Yale School of Public Health who studies why people believe what they believe. He is the author of the award-winning book Misguided and creator of its companion podcast, newsletter, and media literacy tools, all designed to help people navigate today’s complex information landscape.
Your Local Epidemiologist (YLE) comprises a team of experts, ranging from physicians to immunologists to epidemiologists to nutritionists, working together with one goal: to “Translate” ever-evolving public health science so that people are well-equipped to make evidence-based decisions. YLE suite of newsletters reaches over 475,000 people across more than 132 countries. This newsletter is free to everyone, thanks to the generous support of fellow YLE community members. To support the effort, subscribe or upgrade below:
 | A guest post by
|
No. 5 is key. Because you didn't mention how wrong the experts actually are sometimes. I only have my immediate friend and family network to rely on for anecdotal evidence, while social media groups have sometimes provided life-saving advice. Just the things I am personal witness to: incorrect initial diagnosis that, if followed, would have resulted in earlier death; failing to distinguish a type of infection caused by radiation from pneumonia that almost resulted in death; discrediting a patient's insistence that something was wrong that later did, indeed, turn out to be wrong. So, yes, knowledgeable professionals need to be members of social media support groups because ordinary folks so often feel like they're flying blind in a health system with deep flaws.
I'd also note that doctors often are only familiar with their specialty and its received wisdom, and dismissive of the possibility that there are useful treatments from outside it. For example, I have vision impairment from MS. When it started, I asked my neurologist if there was vision therapy I could do, and I was told that it would just get better on its own or I'd have to live with it. 10 years later, I finally self-referred to a neuro-optometrist, who sent me to vision occupational therapy by therapists he had trained at a local stroke rehab center. It was amazing. I was able to return to driving, and I feel so much better. Doctors too frequently know nothing about occupational therapy and physical therapy, and are knee-jerk dismissive of it, even though these are real therapeutic specialties based in science. So when patients see this myopia, no wonder they are inclined to investigate alternative or complementary medicine.