What role do social norms play in the context of men’s cancer screening intention and behavior? Application of an extended theory of planned behavior.

OBJECTIVE: Our research investigated the role of social norms in an extended theory of planned behavior (TPB) in the explanation of prostate/colorectal cancer screening (CS) intention and the prediction of CS uptake among men. DESIGN: A cross-sectional study (Study 1) assessed sociodemographic and TPB variables (extended by descriptive norm) in 2,426 German men (mean age 56.3 years) who differed in their past CS behavior. A subsample of Study 1 (former nonattenders and irregular attenders, n = 1,032) were followed up 12 months later (Study 2). MAIN OUTCOME MEASURES: The authors measured cross-sectionally the intention to undergo a CS examination within the next 12 months (Study 1), and longitudinally self-reported uptake of prostate and/or colorectal CS within the last 12 months (Study 2). RESULTS: When sociodemographic variables were controlled, TPB variables predicted a substantial amount of CS-intention (Delta R2 = .49). Descriptive norm explained variance beyond the classic TPB variables and interacted significantly with subjective norm. Significant predictors of CS uptake were intention and subjective norm with the latter having a different effect in the two subgroups: a high subjective norm (assessed at T1) was associated with higher CS attendance in (former) nonattenders but lower CS attendance in irregular attenders in the following 12 months. CONCLUSION: Social norms play an important role in men's CS intention and behavior. For intention formation, descriptive norm is influential in addition to subjective norm. The fact that a high subjective norm resulted in a lower likelihood of screening among irregular attenders suggests possible reactance effects.