Low incidence of pulmonary complications following nonmyeloablative stem cell transplantation.

Bone marrow transplantation is associated with pulmonary opportunistic infections and immune-mediated pulmonary processes such as idiopathic pneumonia syndrome and bronchiolitis obliterans. The aim of the present study was to test the hypothesis that nonmyeloablative stem cell transplantation (NST) has less adverse effects on the lungs. A review was undertaken of the pulmonary complications occurring in 53 patients with various haematological malignancies, some of whom were considered high-risk patients with chemoresistant disease, who underwent fludarabine-based irradiation-free conditioning for NST performed between March 1996 and October 1998. All data related to transplant procedure, disease outcome, graft-versus-host disease (GVHD), chest imaging, microbial cultures and lung biopsies, were retrieved from information collected prospectively at the time of transplantation. The median follow-up period after transplantation was 45 months, with 35 patients surviving > 100 days. Approximately half of the patients displayed some form of GVHD, with 11% developing severe chronic GVHD. In 17 (32%) patients, the lungs were somehow adversely affected. Only two (3.8%) patients developed a clinical picture consistent with idiopathic pneumonia syndrome and none developed diffuse alveolar haemorrhage or bronchiolitis obliterans. Dose-reduced conditioning is associated with a low rate of pulmonary toxicity and side-effects. These findings may extend understanding of significant immune-mediated complications occurring after bone marrow transplantation.