Cancer Myths and Falsehoods Can Be Deadly | Psychology Today

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Matthew Facciani, Ph.D.

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Cancer Myths and Falsehoods Can Be Deadly

The science behind why bad health information spreads, and how to stop it.

Posted June 19, 2026

Reviewed by Tyler Woods

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Key points

Cancer patients who chose alternative treatments were more than twice as likely to die within five years.

Alternative treatment communities offer real social rewards that facts alone can't counter.

Inaccurate cancer articles are much more likely to be shared online than accurate ones.

Building health literacy and science trust are key tools in the fight against deadly cancer rumors.

Source: Denis Klimov 3000/Shutterstock

When we talk about misinformation, we often focus on its downstream effects: polarization, eroded trust, and fractured public discourse. Yet there is one corner of the misinformation landscape where the consequences are far more immediate, and far easier to measure: cancer.

Cancer misinformation is not a niche concern. An estimated 40% of people will receive a cancer diagnosis in their lifetimes. And a growing body of research links false information about cancer prevention and treatment not only to a polluted online environment, but to real harm in people’s lives. A 2018 study found that cancer patients who chose alternative treatments over conventional ones had more than a twofold increase in the likelihood of death over five years. For colorectal and breast cancer, the mortality risk was 4.5 and 5.6 times greater, respectively. In other words, choosing alternative treatments was associated with a 350% increase in the risk of death from colorectal cancer, and a 460% increase in the risk of death from breast cancer.

Why Cancer Is Uniquely Vulnerable to Misinformation

Misinformation researchers argue that cancer is a model topic for studying misinformation precisely because its consequences are so measurable. Unlike political misinformation, where real-world effects are diffuse and harder to trace, cancer misinformation produces outcomes we can track more directly: treatment adherence, survival rates, mortality.

Several factors make the cancer information environment particularly dangerous.

Cancer is extraordinarily complex. The term describes hundreds of distinct diseases with thousands of treatment options, and clinical practice guidelines have grown exponentially in length between 1996 and 2019. This creates enormous vulnerability to confident-sounding simple answers. There are also powerful financial incentives to exploit that vulnerability: the alternative medicine industry in the U.S. alone was estimated at $30 billion in 2022. This creates strong economic motives to target desperate patients with familiar-sounding, out-of-pocket “treatments” such as high-dose vitamins, supplements, or highly specific diets.

Most cruelly, a cancer diagnosis itself undermines the cognitive resources needed to evaluate information critically. Psychological distress, fatigue, and information overload are common. The patients who most need to make careful decisions are often the least equipped to do so at the moment it matters most.

How Algorithms and Identity Fuel Cancer Misinformation

This 2024 review documents how thoroughly misinformation has saturated the cancer information environment. Across YouTube, TikTok, Instagram, and Twitter, studies consistently find that low-quality content gets more views, more likes, and more shares than accurate content. One study found that inaccurate cancer articles were 28 times more likely to be shared than factual ones. This reflects something fundamental about how social media algorithms work: engagement is rewarded, and fear, hope, and outrage drive engagement more reliably than careful, evidence-based communication.

But there is a deeper reason why flooding the zone with better information fails, and it comes from identity theory. When a belief becomes attached to an important social identity (an anti-establishment worldview, distrust of pharmaceutical companies, a community of fellow patients seeking alternatives), challenging that belief no longer feels like a factual dispute. It feels like a personal attack. People don’t update; they dig in.

This is true across a broad range of domains, including for cancer patients. A diagnosis is itself an enormous identity disruption. In that context, alternative treatment communities can 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 illustrates this in real time. Following a viral podcast episode in which celebrities promoted ivermectin and fenbendazole as off-label cancer treatments, prescribing rates doubled overall and rose more...