Cancer Myths and Falsehoods Can Be Deadly

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 than 2.5 times among cancer patients specifically, across nearly 70 million patient records nationwide. The sharpest increases were among white patients, men, and residents of the South, mirroring the demographic profile of the platforms promoting the claims. The misinformation didn’t spread randomly. It traveled through identity-aligned networks, reaching communities already primed to receive it. Causality is difficult to parse here: we cannot definitively know if the podcast drove the spike in prescriptions or simply mirrored a growing, pre-existing conversation about these unproven treatments.

One important question is how often people who take alternative treatments avoid or delay evidence-based care. I’ve discussed this before, and it would be useful to see more research in this area. Even delays in evidence-based treatment can increase the risk of more serious negative outcomes. By the time a patient deliberates over an unproven treatment, the persuasive work and potential influence has already happened upstream. Only 18% of physicians report any formal training in addressing unproven treatments, despite 99% of oncology practitioners encountering it regularly.

What Would Actually Help Address Cancer Misinformation

There is no single solution. But the research points toward several possibilities.

Clinicians need training not just in the facts but in the communication skills required to address misinformation without triggering identity threat, meeting patients in their values rather than simply correcting their beliefs. The engagement-maximizing algorithms of various social media platforms also help fuel the spread of sensationalism and outright falsehoods. When reflecting on the massive amounts of false information, researchers and communicators need to focus not just on correcting specific false claims but on the social and identity conditions that create susceptibility in the first place.

The same communities that promoted ivermectin for COVID promoted it for cancer. The claim changed; the underlying identity orientation did not. Correcting one claim without addressing the structural conditions that produce the next one is a losing strategy.

This connects to something I keep coming back to in my work on trust: you do not fix a fractured information environment by only broadcasting more facts into the noise. The trusted messengers (the doctor who listens before prescribing, the community figure who knows the family) work because they are in relation with the people they serve. Cancer misinformation thrives in the absence of that relationship, in the gap between a frightened patient and an institution that feels distant.