Ms. Steiner is a 23-year-old Caucasian teacher who has presented with symptoms of gastroesophageal reflux disease (GERD), diagnosed by an upper gastrointestinal study. She does not have any cell changes since the GERD is a new problem. She is currently a smoker and tends to drink socially while smoking on the weekends. Which risk factor presents the greatest risk for her in developing esophageal cancer at a later time?