"Obesity is the New Major Cause of Cancer": Connections Between Obesity and Cancer on Facebook and Twitter.

Social media interactions can inform public health risk perceptions. While research has examined the risk relationships between obesity and cancer, public attitudes about their associations remain largely unknown. We explored how these constructs were discussed together on two social media platforms. Publicly accessible Facebook and Twitter posts from a 2-month period in 2012 containing references to obesity ("obese/obesity," "overweight," and "fat") and cancer-related words were extracted (N = 3702 posts). Data cleaning yielded a final set of 1382 posts (Facebook: N = 291; Twitter: N = 1091). Using a mixed-methods approach, themes were inductively generated, and sentiment valence, structural elements, and epistemic stance were coded. Seven relational themes emerged: obesity is associated with cancer (n = 389), additional factors are associated with both obesity and cancer (n = 335), obesity causes cancer (n = 85), cancer causes obesity (n = 6), obesity is not linked to cancer (n = 13), co-occurrence (n = 492), and obesity is valued differently than cancer (n = 60). Fifty-nine percent of posts focused on an associative or causal link between obesity and cancer. Thirty-one percent of posts contained positive and/or negative sentiment. Facebook was more likely to contain any sentiment, but Twitter contained proportionately more negative sentiment. Concurrent qualitative analysis revealed a dominance of individual blame for overweight/obese persons and more support and empathy for cancer survivors. Our study reflects wide recognition of the evidence linking obesity to increased risk of cancer, a diverse set of factors perceived to be dually associated with both conditions and differing attribution of responsibility. We demonstrate that social media monitoring can provide an important gauge of public health risk perception.