1. Department of Family Medicine, Chonnam National University Hwasun Hospital, Hwasun, Korea.
2. Chonnam Tobacco Control Center, Chonnam National University Hwasun Hospital, Hwasun, Korea.
3. Department of Family Medicine, Chonnam National University Medical School, Gwangju, Korea.
4. Lung and Esophageal Cancer Clinic, Chonnam National University Hwasun Hospital, Hwasun, Korea.
5. Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea.
6. Department of Nursing, Nambu University, Gwangju, Korea.
7. Department of Preventive Medicine, Chonnam National University Medical School, Gwangju, Korea.