Building resistance, fostering protection: an inoculation-based skin cancer prevention study in socio-educational priority schools

Early exposure to ultraviolet radiation increases the risk of melanoma later in life, making the prevention of risky sun behaviors during adolescence a public health priority. This study evaluated a theory-based school sun-safety intervention combining Protection Motivation Theory, implementation intentions, and the Theory of Planned Behavior, with an additional inoculation component designed to strengthen resistance to social influence. The preregistered study was conducted in a French middle school with five 8th-grade classes randomly assigned to either an experimental condition (inoculation) or a control condition (without inoculation). Students completed questionnaires at three time points (baseline, immediate post-intervention, and one-week follow-up) assessing knowledge, attitudes, subjective norms, perceived behavioral control, protection motivation, and behavioral intention. After implementation in additional schools, exploratory analyses were conducted on an extended multi-school sample. Behavioral intention and knowledge increased significantly from baseline to post-intervention in both conditions, with no significant time × group interaction. Exploratory analyses on the larger implementation sample also suggested improvements over time in behavioral intention, knowledge, and some psychosocial determinants. Theory-based school interventions can improve adolescents’ knowledge and intentions regarding sun protection. The inoculation component did not produce clear additional effects beyond the standard intervention.