Effects of communicating lifetime risks and screening rates of colorectal cancer and breast cancer

Colorectal cancer and breast cancer are among the most common types of cancer in the United States, and cancer screening is an effective way to detect and treat these cancers early. Health news stories, medical websites, and media campaigns regularly highlight the national lifetime risks of specific cancers and their screening rates, but recent research suggests that people tend to overestimate the prevalence of health problems but underestimate the prevalence of disease prevention behaviors in the absence of numerical information. This study featured two online experiments, one focused on breast cancer (N = 632) and one focused on colorectal cancer (N = 671), to examine the effects of communicating national cancer lifetime risks and screening rates among samples of screening-eligible adults in the United States. Findings confirmed prior work in showing that people overestimated colorectal/breast cancer lifetime risks but underestimated colorectal/breast cancer screening rates. Communicating the national lifetime risk of dying from colorectal/breast cancer lowered people's national risk estimates, which in turn was associated with lower perceived cancer risks for themselves. In contrast, communicating the national colorectal/breast cancer screening rate increased people's estimates of the prevalence of cancer screening, which in turn was associated with higher perceived self-efficacy to engage in cancer screening and greater screening intentions. We conclude that efforts to promote cancer screening may benefit from messages that include data on national cancer screening rates but may not benefit from including national rates of lifetime cancer risks.