Smoking Relapse Prevention in Patients With Cancer

This randomized controlled trial will evaluate whether adding one-session structured cognitive behavioral therapy (CBT)-based relapse-prevention counseling to standardized brief relapse-prevention counseling improves smoking abstinence among patients with cancer who smoked cigarettes at diagnosis and have remained completely abstinent from diagnosis until enrollment. After written consent and baseline assessment, all participants will receive the same standardized brief relapse-prevention counseling. Participants will then be randomly assigned 1:1 to no additional study CBT or to one additional structured CBT-based relapse-prevention session. Follow-up will continue for 3 months after randomization at Campus 3 of Vietnam National Cancer Hospital in Hanoi, Vietnam.

Inclusion Criteria: 1. Aged 18 years or older. 2. Diagnosed with cancer. 3. Was smoking combustible cigarettes at the time of cancer diagnosis. 4. Has remained completely abstinent from cigarette smoking from the time of cancer diagnosis until study enrollment, without smoking even a puff. 5. Provides written informed consent to participate in the study. Exclusion Criteria: 1. Have a medical, psychiatric, cognitive, hearing, speech, or other condition that prevents effective communication or meaningful participation in the counseling intervention or study assessments. 2. Are not expected to be contactable or able to complete the planned follow-up assessments. 3. Are currently using other combustible tobacco products, such as waterpipe tobacco, shisha/hookah, cigars, or pipes. 4. Are currently participating in another structured smoking-cessation intervention or clinical trial that could materially affect the study outcomes.