Construction and Preliminary Evaluation of Dyadic Acceptance and Commitment Therapy for Couples With Fear of Lung Cancer Recurrence

The goal of this clinical trial is to develop a simple, scientific, effective, and culturally adapted dyadic Acceptance and Commitment Therapy (ACT) intervention program (the ADAPT program) targeting fear of cancer recurrence (FCR) among lung cancer patients and their spouse caregivers. The study will also evaluate the feasibility, acceptability, and preliminary effectiveness of the ADAPT program. The main research questions are as follows: * Is the ADAPT intervention program feasible and acceptable for lung cancer patients and their spouse caregivers? * Compared with usual care, can the ADAPT intervention program preliminarily reduce FCR levels in both patients and their spouse caregivers? Can the program improve coping styles, illness perceptions, family functioning, and intimate relationships among both patients and their spouse caregivers? Can the program enhance psychological flexibility and quality of life (QOL) in both patients and their spouse caregivers? Researchers will compare the ADAPT intervention program with usual care to evaluate its preliminary effectiveness in reducing FCR among lung cancer patients and their spouse caregivers. Participants will: * Receive the ADAPT intervention twice during each radiotherapy and/or chemotherapy cycle, for a total of three treatment cycles (approximately 3 months); * Complete questionnaires at baseline (before the intervention), immediately after the intervention, and one month post-intervention; * Report outcomes including FCR severity, FCR triggers, psychological flexibility, illness perception, dyadic coping, family functioning, intimacy, and quality of life (QOL).