From Diagnosis to Behaviour Change: Applying the Health Action Process Approach to Smoking Cessation After Head and...

Smoking cessation after a cancer diagnosis is a key determinant of prognosis, yet the psychological mechanisms underlying cessation remain poorly understood. Building on a recently validated Health Action Process Approach (HAPA) scale, this study examined whether baseline HAPA constructs predicted short-term smoking cessation and tobacco dependence in patients with head and neck cancer. Eighty-nine patients completed assessments at diagnosis (T0) and one-month follow-up (T1). Six HAPA constructs were measured at T0: Risk Perception, Outcome Expectancies, Recovery Self-Efficacy, Behavioral Intention, Coping Planning, and Action Control Efficacy. Smoking outcomes at T1 included cigarette dependence (CDS-12) and smoking status. Hierarchical linear regression showed that sociodemographic and clinical variables did not predict dependence, whereas adding HAPA constructs significantly improved prediction (ΔR² = 0.28, p < 0.001). Higher Risk Perception and Outcome Expectancies were associated with greater dependence, while logistic regression identified Action Control Efficacy as the only independent predictor of smoking cessation. These findings provide the first longitudinal evidence supporting the application of the HAPA framework to smoking cessation after cancer diagnosis and underscore the critical role of volitional processes in early cessation. Targeting action control may therefore enhance the effectiveness of smoking cessation interventions in oncology settings.