Clinical impact of cigarette smoking on the outcomes of allogeneic hematopoietic stem cell transplantation: a multicenter retrospective study.

Smoking is associated with a high risk for different diseases including respiratory tract infections in immunocompetent patients. However, data about the effects of cigarette smoking on the outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) are limited. Therefore, we retrospectively investigated 608 patients aged ≥20 years with hematological disorders who received their first allo-HSCT at our group of hospitals between 2000 and 2015, and evaluated the impact of cigarette smoking before allo-HSCT on clinical outcomes by dividing patients into two groups according to the Brinkman index (BI) (nonsmokers or light smokers [BI: 0-500] and heavy smokers [BI: ≥ 500]). Multivariate analyses showed that heavy smoking was associated with a high 5-year cumulative incidence of chronic graft-versus-host disease (cGVHD) (hazard ratio [HR]: 1.73, 95% confidence interval [CI]: 1.15-2.61, p < 0.01). The 5-year overall survival (HR: 1.16, 95% CI: 0.86-1.58, p = 0.33) and disease-free survival (HR: 1.12, 95% CI: 0.83-1.52, p = 0.45) were similar between the two groups. Hence, cigarette smoking is correlated with cGVHD, although prospective studies must be conducted to further verify this result.