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.