Cancer misinformation has become an increasingly prevalent problem, imperiling public health and understanding. Cancer researchers and clinicians must play a significant role in combating its detrimental consequences.
There are few subjects as emotive—or as perpetually misunderstood—as cancer. A small word with outsized ramifications, it remains poorly understood by the public, despite its sheer ubiquity. Although pioneering cancer research has ensured that survival has never been better, it is for many people an uncomfortable reminder of their own mortality, an issue to be avoided or referred to only in cloaked euphemism. Outside those in the field of oncology, cancer is a subject many do not give serious thought to until they or a loved one are diagnosed. Yet those searching for information about cancer both online and off are too frequently accosted by a cacophony of false claims, from well-meaning but dangerous advice to callous exploitation by charlatans. For cancer researchers and clinicians, understanding this explosive informational landscape is vital to stem deleterious impacts.
One of the defining traits of the ongoing COVID-19 pandemic has been the alarming rise of a shadow plague of poisonous fictions in its wake. The sheer abundance of misleading information was dubbed by the World Health Organization as an “infodemic,” or the “overabundance of information, some accurate and some not, that makes it hard for people to find trustworthy sources and reliable guidance when they need it.” Long before the pandemic, however, misinformation was already a problem for cancer science. One 2016 report suggested more than half of the most widely shared cancer articles on Facebook consisted of medically discredited claims. A more recent study on the 50 most popular social media articles on the four most common types of cancers found dangerous misinformation in more than 30% of the articles analyzed and, perversely, that these articles garnered more online engagement than factual articles (1). A 2020 investigation found that cancer misinformation on social media altered young adult caregivers' health behaviors and decision-making (2), whereas examination of posts on Facebook groups for parents of children with acute lymphoblastic leukemia deemed approximately one third of the shared information to be medical misinformation (3). Analysis of cancer-related keywords on Twitter also suggests that misinformation is dominant on that platform (4).
The extent of cancer falsehoods online and their precise impact is an emerging area of scholarship, and is impossible to quantify precisely for now. It is worth noting, however, that falsehoods about cancer are not a strictly modern occurrence—long before the dominance of social media, wrongheaded narratives were a serious problem. The era of patent medicine saw numerous ignoble examples, such as “Rattlesnake King” Clark Stanley, who in 1893 peddled a concoction wrung from snakes to huge audiences at the Chicago World's Fair. Such theatricality accrued large profits, requiring the slaughter of more than 5,000 snakes annually to meet demand. Later investigation by the newly minted FDA, however, revealed Stanley's marvelous medicine to be nothing more than mineral oil and turpentine—giving us the term “snake oil” for all ineffectual elixirs. Years later, following a spate of high-profile instances of patients being exploited by cancer quackery, the United Kingdom passed the Cancer Act in 1939, outlawing the hawking of ostensible cures to the public.
The commercialization of false promises and suspect claims is thus not a new phenomenon. What has changed utterly in recent decades is the sheer rapidity with which such claims can proliferate and the audiences they can reach. As cancer surgeon and longtime debunker of pseudoscience David Gorski observes, cancer misinformation is “way more prevalent now for the same reason other misinformation and conspiracy theories are so prevalent—because they're so easily spread on social media.” One recent editorial lamented the growing dominance of cancer misinformation, asking, “How has society got to this point, where unproven interventions are being chosen in preference to evidence-based, effective treatments? Unfortunately, disinformation and—frankly—lies are propagated widely and with the same magnitude as verified evidence” (5).
There are several reasons why public understanding of cancer is in an especially precarious position. Those most susceptible to cancer misinformation tend to have poor health literacy and lower trust in health care, as well as lower levels of educational attainment and most positive views toward alternative medicine (6). However, susceptibility to cancer falsehoods is not a simple function of intelligence or education; evidence to date indicates we are collectively poor at differentiating between reputable and reprehensible sources. Psychologic factors also prime the unsuspecting toward acceptance of dubious claims. For example, the availability heuristic is the observation that we tend to afford higher weight to claims that are more vivid and memorable, implicitly favoring simpler, more accessible narratives over less certain, more reliable information. The constant repetition of incorrect claims about cancer also renders use pliable to the phenomenon of illusory truth, in which repetition of a claim induces us to implicitly accept it more readily, even if we are aware on an intellectual level that it is false.
In this environment, misinformation about cancer readily proliferates, but why precisely does it arise and thrive in the first instance? To researchers, it might seem counterintuitive that dangerous falsehoods could even be entertained regarding something as serious and rigorously studied as cancer, but this is a remarkably different perspective from that of many patients and their families. Even before the dawn of social media, cancer misconceptions such as the mistaken idea that surgery “spreads” tumor cells around the body were commonly held, as was the enduring belief that there exists a universal panacea for cancer (7). Although public misconceptions around cancer causes, treatments, and cures have long abounded, the emergence of social media has had a drastic impact on the diffusion of mistaken ideas (1). Following diagnosis, patients are frequently overwhelmed by oncologic advice from friends, relatives, and fellow patients. Much of this distilled advice is garnered from online sources, with scant consideration of accuracy or veracity. The lack of expertise underpinning such well-meaning but potentially misguided interjections is no impediment to their acceptance from patients (8). It is worthwhile to delve into how misinformation manifests to understand why it is so intrinsically appealing.
The first category of misinformation is inadvertently misleading information propagated without intention to deceive. Enduring myths often stem from a kernel of truth, albeit one utterly mangled by serious misunderstanding. For example, a persistent assertion that cannabis and its derivatives can cure cancer, although false, is often buttressed by a misunderstanding of findings that tetrahydrocannabinol, the chief psychoactive agent in cannabis, kills plated cancer cells. However, this observation is clinically irrelevant, given the triviality of killing cells in a petri dish, which can perish under heat, bleach, acid, and an entire litany of cytotoxic agents. The canard depends on a lack of understanding that cancer cells grown in vitro are devoid of the requisite context and microenvironment in which effective anticancer agents discriminately kill tumor cells in vivo while sparing healthy tissue. Similar misconceptions arise in the abundance of popular “cancer-beating” diets, evangelized everywhere from social media to best-selling books. Although diet may have a role to play in improving treatment response, overinterpretation of preclinical findings too often sees diet wrongly presented as a panacea to cancer.
That such misunderstandings can occur organically without any intention to mislead is entirely understandable. However, innocent misunderstandings only account for a certain fraction of cancer misinformation. Disinformation, the deliberate vectoring of false information, is also a persistent problem in cancer. It seems perverse that anyone would foist fictions about cancer on patients with deliberate intent, but cancer disinformation is often the consequence of evangelism by those who for ideological or financial reasons push treatments unsupported by evidence. The complementary and alternative medicine (CAM) community is a frequent offender—although there are several competing definitions of “alternative medicine,” it is broadly defined as interventions either not proven to work or shown as ineffective in clinical trials. Believers tend to subscribe to postmodern or spiritual belief systems, valuing intuition over evidence and frequently depending on confusion of vital concepts (9). CAM users also tend to attribute disease to psychologic or lifestyle factors, believing they exert active control over their illness (10).
An empirical deficit of evidence is thus not an impediment for CAM acceptance in many cohorts. Indeed, even the need for testing complementary or alternative interventions is often denied (9), which has an unfortunate side effect, as adherents tend to proselytize their claims without due regard to the evidence base. This evangelization typically manifests as copious anecdotal claims of great efficacy, despite a paucity of evidence (or abundance of counterevidence) for these assertions. Some CAM therapies in cancer can even be worse than useless, with a number antagonizing effectual therapy. CAM use has grown steadily in recent years; an estimated 51% of oncology patients engage in CAM modalities (10), the majority of whom believe they can treat or cure their cancer. Although many of the patients who use CAM use it in a strictly complementary manner in addition to conventional treatment, the reality is that alternative use also exists, in which effective treatments are jettisoned for unproven or disproven modalities. Alternative therapy is intimately entangled with yet another darker motivator for CAM acceptance—the perception that there is a conspiracy by pharmaceutical companies and cancer researchers to suppress a cure for cancer (11, 12).
Conspiracy theories about a hidden cure for cancer are rife both online and off. An astounding 37% of the American public surveyed in 2014 believed that the FDA intentionally suppressed “natural” cures for cancer at the behest of pharmaceutical companies (13). The same survey also found that 20% of participants believed that corporate entities were suppressing evidence that cell phones cause cancer. Inevitably, conspiracy theories require a villain—and whether intentionally or by happenstance, such beliefs cast cancer clinicians and researchers as pantomime villains in a heartless quest to suppress the efficacy of some ineffable panacea. Worse, these narratives nudge unsuspecting audiences toward rejection of medical evidence and foster needless distrust between patients, clinicians, and researchers.
By embracing conspiracy theory, a complete lack of reputable scientific evidence can be readily explained away in a useful deus ex machina. This “big pharma” gambit is a constant and toxic refrain underlying much cancer misinformation. Conspiracy researcher Robert Blaskiewicz (14) defines it as “shorthand for an abstract entity comprised of corporations, regulators, NGOs, politicians, and often physicians, all with a finger in the trillion-dollar prescription pharmaceutical pie,” noting that “eliding all of these separate entities into a monolithic agent of evil allows the conspiracy theorist to mistakenly ignore the complex and conflicting interests that they represent.” The consequences of this conspiracy theory imperil lives and kill patients; those who subscribe to alternative approaches are more than twice as likely to die in the same period as those who rely on conventional therapies due to either delaying or even rejecting conventional treatment (15).
Even worse, promoters of unproven therapies frequently resort to scaremongering over conventional therapy, dismissing interventions such as radiotherapy and chemotherapy as “poisons.” This dark refrain appears with alarming frequency on alternative health sites, amplifying the fears of patients and making them more malleable to dubious treatments that promise perfect efficacy and no side effects. Many of these wares are lauded as “natural” cures, with the loaded implication that they are thus superior to “synthetic” cancer drugs. This is the epitome of the “appeal to nature” fallacy, which is flawed for multiple reasons. The problem is that the adjective “natural” is inherently ambiguous. Virtually all plant and animal products we use have been selectively bred or otherwise engineered for millennia by humans. Many pharmaceutical products have been derived from agents found in the wild, carefully experimented upon to determine the active ingredient and control dose. Even if we charitably define “natural” to mean those agents that occur without direct human intervention, the problem is not circumvented; arsenic, uranium, and deadly nightshade are “natural,” but one would be extremely ill-advised to incorporate them into their medicine cabinet.
Under critical examination, the allure of alternative medicine is founded on illusion, wishful thinking, and slick marketing. This shaky foundation, however, is no impediment to its wide acceptance; an estimated 40% of the American population believe that cancer can be cured by alternative medicine alone (16). Emotive testimonials also play a part in amplifying cancer misinformation to vulnerable patients; the rise of dubious clinics around the world, usually in poorly regulated regions, is an ignoble exemplar. These clinics have proven adept at commercializing false hope, charging hundreds of thousands of dollars for their ostensibly miraculous services. Were this not galling enough, many of these outfits have the audacity to co-opt patient testimonials for future recruitment, which they often continue to trumpet long after the patient is deceased and their family saddled with huge debts (17).
Cancer disinformation does not solely concern ostensible treatments, however. Because fear of cancer is so deeply ingrained, ideological opponents of certain undertakings can readily infer a nonexistent association with cancer to buttress their rhetoric. Examples of such disinformation are legion; opponents of the human papillomavirus vaccine, itself cancer-preventing, have tried to insinuate a link between the vaccine and the cancer it prevents. Opponents of everything from 5G technology to water fluoridation to abortion have repeatedly tried to link these practices to cancer, despite a complete lack of evidence or mechanism for these assertions. Vapid and cynical as these attempts might be, fear of cancer is so pronounced that false conflations can persist in societal collective consciousness long after being debunked, fueling confusion and paving the way for further misinformation.
There are thus myriad reasons patients are vulnerable to cancer misinformation: its sheer ubiquity, coupled with anecdotal vividness, certainly plays a role. For others, a lingering distrust of conventional medicine or postmodernist antiempirical worldview and intuitive thinking style predispose them to such untrue statements. However, cancer misinformation also offers something uniquely alluring missing from much of legitimate cancer research: an illusion of certainty. In contrast, like all science, cancer research is laden with unavoidable caveats and uncertainty. The narratives of cancer misinformation seduce with a veneer of simplicity and surety. The simplistic mantras of cancer misinformation promise easy answers and reassuring certainty that the sheer complexity of cancer would not allow scientists or physicians to make in good faith.
This dubious amplification of pseudoscience diminishes trust in the medico-scientific sphere (18). Cancer misinformation is harmful even when it is not fully embraced or believed, precisely because it creates a lingering impression that no medical consensus exists on the topic or that official sources of information lack credibility (19). This impression, in turn, leads to an atmosphere of confusion, apathy, and distrust. The net effect of the resultant apathy and confusion is that individuals, unsure of what to believe, disengage from seeking reliable health information. Such a grim-seeming prognosis is not inevitable—and here, researchers and clinicians have a pivotal role to play in turning the tide of misinformation.
One aspect involves improving our communication and interpretation of research findings. Many misconceptions ultimately stem from reductive or out-of-context understanding of aspects of cancer research, whereas others derive from an outright rejection or distortion of medical science. For researchers and clinicians, it is an important point to realize that scientific findings may be innocently misunderstood or distorted by those with vested interests. Accordingly, it is important for scientists and physicians to be cognizant not only of the scientific findings but also about how they may be misinterpreted or distorted, as well as to provide the context essential to parsing the findings so that confusion does not arise. This problem is not trivial to address, as it can be difficult to predict precisely how information will be used, but what is certain is that scientists occupy a trusted role in society, and interventions by scientists and physicians can markedly augment public understanding.
It is also critical to realize that there is not simple binary distribution of those who will reject or accept scientific information on cancer. Acceptance of medico-scientific beliefs is a spectrum (19), and medical misinformation tends to nudge people collectively toward rejection of science. However, scientists and doctors remain a highly trusted component of society, and appropriate interventions by the cancer research community can be highly beneficial. There is emerging evidence too that expert intervention and dedicating debunking of health myths has a substantial effect toward nullifying misinformation (20, 21). Health literacy remains an overwhelming determinant of acceptance and propagation of health misinformation, but there remains much work to be done in ascertaining how best to improve health literacy around cancer (22). It is vital to realize that deep-seated fears underpin much of the acceptance of cancer misinformation, and this reality is often exploited by those disseminating falsehoods. Outreach events and discussions of fears might do much to offset the acceptance of misinformation and to buttress trust in the scientific profession. What best works at combating health misinformation remains an underresearched but increasingly critical area as the impact of social media fictions becomes more widely recognized and acute.
There are lessons that can be learned from interventions to counter scientific conspiracy theories, especially efforts to counter antivaccine propaganda. Previous investigation indicates that improved communication of knowledge of the scientific consensus can also overcome some conspiratorial thinking on issues as diverse as the link between human immunodeficiency virus and AIDS to acceptance of climate change. Such Socratic approaches have been also shown to reduce beliefs that the moon landing was a hoax (12). We might take the “hidden” cure for cancer narrative as an illustrative example, explaining that, far from being a monolithic entity, cancer is not one illness but an entire family of more than 200 diseases, differing greatly between tissue type and even individual. How these malignancies respond to different interventions varies hugely, rendering the idea of a single “magic bullet” for all these myriad types exceptionally unlikely. The benefit of this approach is that it takes concerns seriously while still showing the concerns to be unfounded, ultimately improving understanding.
In the long term, however, prevention is better than cure. The growing prevalence of cancer misinformation is a microcosm of the wider problem of scientific disinformation (23). The ideal long-term solution is to improve our societal critical thinking skills, teaching people to source and parse information so that they may distinguish the reputable from the reprehensible. We cannot rely on social media companies to act in the public good without the unlikely imposition of pan-national external regulation, nor will automated solutions suffice. The abundance of disinformation during the pandemic serves as a painful testament that information itself must be recognized as potentially pathogenic, capable of infecting and making vectors of people to their lasting detriment.
A major part of this issue transcends cancer science—it is also crucial that the wider research community instill a better understanding of what science is and what it is not. It is an unfortunate reality that although scientists and doctors as a collective are well trusted, the scientific endeavor and overall philosophy of science remain poorly understood by the public. Widespread ignorance of the scientific method has manifested to our detriment throughout the pandemic, well illustrated by the highly transient state of COVID-19 research. Good science proceeds by testing, rejecting, and refining the progress that came before. To those unfamiliar with the intricacies of the scientific method, however, it is entirely understandable that the rapid flux of knowledge might seem to indicate that science itself is clueless.
Some degree of scientific disagreement is unavoidable and healthy at the frontiers of science. Decidedly less healthy, however, is the ugly spectacle of ostensibly qualified individuals making proclamations drastically at odds with the evidence base, something we have unfortunately seen throughout the pandemic, with a cacophony of contrarian opinion from credentialed sources. To many, this discordance creates the impression that science is merely a matter of opinion and that scientists are at best self-important pundits and all viewpoints are equally valid. Scientific opinions are, however, entirely weighed by the evidence supporting them. A scientist speaks with any authority only when they are accurately reflecting the evidence base and consensus. Once they fail to honestly interpret the evidence, their qualifications account for nothing, nor do they shield them from being wrong.
It is critical, then, that we in the scientific community highlight that science progresses based on the strength of evidence for each proposition, not the volume at which opinions are proclaimed. A better understanding of what science is—and what it is not—would be a substantial boon to society. The scientific community also has a vital role to play in striving toward a policy of information hygiene, encouraging and empowering individuals to share only substantiated and verified claims, as well as sharing insights into how to interrogate claims before they take root. It is imperative that the cancer research community be at the vanguard of the pushback against cancer misinformation and equally vital that we are cognizant of the growing scale of the problem. Improving health literacy in general will pay huge societal dividends (24). Ultimately, encouraging a healthy skepticism may serve as our best protection against the ravages of cancer misinformation.
No disclosures were reported.
David Robert Grimes thanks the Wellcome Trust (Grant 214461/A/18/Z) for their support.