Comparison of Lung Function after Nonmyeloablative Versus Myeloablative Allogeneic Hematopoietic Stem Cell Transplantation.

Lung function decline is a well-recognized occurrence after myeloablative hematopoietic stem cell transplantation (HCT) that has not been studied after nonmyeloablative conditioning regimens. We examined the lung function of patients before and after receiving nonmyeloablative and myeloablative preparative regimens. Before HCT, nonmyeloablative patients had lower baseline values of percent of predicted FEV₁ (pFEV₁) and FVC (pFVC), reflecting their greater ages and often, poorer, medical conditions. However, nonmyeloablative patients experienced a slower overall rate of pFEV₁ decline after HCT (4% ± 17 versus 12.7% ± 32 per year, P = 0.001), with patients >50 years of age having the lowest risk for rapid pFEV₁ decline in a multivariable model. Rapid pFEV₁ decline was associated with both total body irradiation (TBI) and non-TBI based myeloablative regimens. These findings were evident even one year or more after HCT. Myeloablative patients had a higher risk for death based upon pretransplant pFEV₁ (HR 7.2 versus 3.9), with a 2-year survival rate of 0% among myeloablative patients with a pretransplant pFEV₁ <60% (30% among nonmyeloablative patients). These results suggested that despite having worse lung function, patients receiving the nonmyeloablative regimen might experience less pulmonary toxicity and had a lower risk of mortality associated with abnormal pretransplant lung function.