Intention to complete advance directives among patients with cancer undergoing treatment: application of the extended theory of planned behavior.

PURPOSE: To examine psychosocial and clinical factors associated with the intention to complete advance directives among patients with cancer undergoing treatment in South Korea.

METHODS

Structured questionnaires assessed 200 patients receiving cancer treatment for their attitudes toward advance directives, subjective norm, perceived behavioral control, knowledge about advance directives, and cancer-related fatigue. Hierarchical multiple regression analysis was conducted in three steps: Step 1 included attitude and subjective norm (Theory of Reasoned Action); Step 2 added perceived behavioral control (Theory of Planned Behavior); and Step 3 incorporated knowledge and cancer-related fatigue (Extended Theory of Planned Behavior).

RESULTS

Attitude, subjective norm, and perceived behavioral control significantly predicted behavioral intention, explaining 74.1% of the variance. Perceived behavioral control had the strongest effect. Knowledge and cancer-related fatigue were not statistically significant.

CONCLUSIONS

These findings highlight the Extended Theory of Planned Behavior as a useful framework for understanding advance directive completion among cancer patients. Perceived behavioral control was identified as the strongest predictor of intention, underscoring the importance of enhancing patients' confidence and ability to engage in advance care planning. The results suggest that structured counseling and tailored education should be initiated early in the treatment process to support autonomous decision making that reflects patients' values and preferences for end-of-life care. Interventions that strengthen attitudes, foster supportive norms, and build perceived control may further promote advance directive planning.