Cigarette smoking and outcomes after allogeneic hematopoietic stem cell transplantation.

Abnormal lung function is a known risk factor for poor outcomes in the allogeneic hematopoietic stem cell transplantation (HSCT) population, although the specific causes of these abnormalities have not been well explored. There is limited data on the effect of cigarette smoking on transplantation outcomes. We conducted a retrospective observational cohort study of 845 consecutive patients age ≥ 18 years who underwent allogeneic HSCT at the Seattle Cancer Care Alliance/Fred Hutchinson Cancer Research Center. Smoking exposure was defined by quit time, smoking status (never, former, and current), and log(2)-transformed pack-years. The main outcomes were time to respiratory failure within 100 days of transplantation, relapse, and nonrelapse mortality. In multivariable analyses, a 2-fold increase in pack-years smoked was associated with an increased risk of early respiratory failure (hazard ratio [HR] 1.33, 95% confidence interval [CI] 1.09 to 1.64, P = .006). This association was observed independent of pretransplantation lung function. A 2-fold increase in pack-years smoked was associated with an increased risk of relapse, but this finding was not statistically significant (HR 1.16, 95% CI 0.92-1.46, P = .21). An association was not observed between cigarette smoking and nonrelapse mortality. Cigarette smoking is associated with an increased risk of respiratory failure and relapse within 100 days of allogeneic HSCT. The association with respiratory failure is mediated in part by abnormal lung function before transplantation and likely through other mechanisms as well. Given the adverse effects associated with cigarette smoking before transplantation, future studies should focus on obtaining accurate smoking histories, tracking prospective changes in smoking status, and assessing the benefits of tobacco cessation on outcomes in this population.