Background:
Cancer-related misinformation is a growing public health problem that can influence public perceptions and health-related decisions. Beliefs in mythical causes (i.e., factors not established as cancer causes), alternative therapies without proven benefits, conspiracy narratives, and uncritical exposure to false social media content may undermine the adoption of preventive behaviors and appropriate use of health services.
Objectives:
We investigated the prevalence of non–evidence-based cancer beliefs and susceptibility to cancer-related misinformation in a representative sample of Spanish adults. We further examined variations according to sociodemographic factors and assessed whether knowledge of the European Code against Cancer (ECAC) and its recommendations is associated with lower susceptibility to misinformation.
Methods:
We conducted a cross-sectional survey on a representative sample of 3,000 Spanish adults aged 18–75 years. Non-evidence-based beliefs about cancer causes and treatment were measured using previously validated Spanish versions of the Cancer Awareness Measure–Mythical Causes Scale, the Cancer Treatment Conspiracy Beliefs questionnaire, and a questionnaire assessing beliefs in the effectiveness of 13 non-evidence-based practices (e.g., meditation, herbs, homeopathy, supplements…) as preventive, complementary or alternative treatments. Susceptibility to cancer-related misinformation was assessed using a previously validated methodology. Participants were shown eight cancer-related social media posts (four containing false and four containing accurate information) and classified each as true or false. Familiarity with the ECAC and its recommendations was assessed using the Cancer Prevention Literacy Questionnaire (CPL-Q). Multivariable regression models examined differences in beliefs and misinformation susceptibility across sociodemographic groups and associations with ECAC familiarity and knowledge.
Results:
On average, participants endorsed 4 out of 12 mythical causes of cancer (standard deviation SD = 3.5). They believed that, on average, 3 of the 13 non–evidence-based practices could be effective for cancer prevention, 4 for use as complementary treatments, and 1 as an alternative treatment. Susceptibility to false information was high, with participants classifying on average 2.6 out of 4 highly misleading social media posts as true (SD = 1.56). Non–evidence-based beliefs about cancer were more prevalent among younger individuals, women, and rural residents, except for conspiracy beliefs, which were higher among men. Familiarity with the ECAC and knowledge of its recommendations were associated with a higher prevalence of non-evidence-based beliefs and did not protect against misinformation. The only factor consistently associated with lower susceptibility to misinformation was having been diagnosed with cancer.
Conclusions / Implications for practice or policy:
Participants showed high susceptibility to misleading cancer-related information presented in real social media posts. Overall, non–evidence-based beliefs are widespread and socially patterned in the Spanish adult population. Knowledge of cancer prevention recommendations alone is not sufficient to protect against misinformation, highlighting the need for targeted communication strategies that directly address false beliefs and misinformation.
Funding: Social Observatory of la Caixa Foundation (FS24-2B178)