Psychosocial Predictors of Colorectal Cancer Screening Intention: An Experiment on the Invitation Letter

In Italy, attendance rates for colorectal cancer (CRC) screening are suboptimal. The present work analysed cognitive and emotional predictors of CRC screening intention and tested an intervention on a real invitation letter to improve CRC screening intention, both directly and in interaction with the predictors of our model.

Our model included variables from the theory of planned behaviour and the emotional barriers to bowel screening scale. We applied six changes to an invitation letter used in Italy to avoid the repetition of words like 'faeces', 'blood', or 'occult' and reduce the prompting of disgust. The 228 participants were randomly assigned to a between-participants design (original letter vs. manipulated letter).

Disgust hindered CRC screening intention, while embarrassment, fear, and subjective norms (i.e., perception of the social pressures to attend CRC screening) were not associated with intention to screen. More positive attitudes towards CRC screening were associated with a higher intention to screen. The positive association between perceived behavioural control and CRC screening intention was stronger for participants who read the letter with fewer (vs. more) references to bodily waste. Letter manipulation did not affect intention to screen.

The disgust associated with faecal matter is a critical factor in determining CRC screening attendance, and it should be acknowledged as such in public policies. Until new screening tests avoiding the activation of this emotional reaction are concretely available, public campaigns should improve CRC screening participation by boosting both positive attitudes towards screening and patients' perceived behavioural control.