Early lymphocyte recovery as a predictor of outcome, including relapse, after hematopoietic stem cell transplantation

BACKGROUND Despite advances in the treatment of acute leukemia, many patients need to undergo hematopoietic stem cell transplantation. Recent studies show that early lymphocyte recovery may be a predictor of relapse and survival in these patients. OBJECTIVE To analyze the influence of lymphocyte recovery on Days +30 and +100 post-transplant on the occurrence of relapse and survival. METHODS A descriptive, retrospective study was performed of 137 under 21-year-old patients who we resubmitted to hematopoietic stem cell transplantation for acute leukemia between 1995 and 2008. A lymphocyte count < 0.3 x 10(9)/L on Day +30 post-transplant was considered to be inadequate lymphocyte recovery and counts ≥ 0.3 x 10(9)/L were considered adequate. Lymphocyte recovery was also analyzed on Day +100 with < 0.75 x 10(9)/Land ≤ 0.75 x 10(9)/L being considered inadequate and adequate lymphocyte recovery, respectively. RESULTS There was no significant difference in the occurrence of relapse between patients with inadequate and adequate lymphocyte recovery on Day +30 post-transplant. However, the transplant-related mortality was significantly higher in patients with inadequate recovery on Day +30. Patients with inadequate lymphocyte recovery on Day +30 had worse overall survival and relapse-free survival than patients with adequate recovery. There was no significant difference in the occurrence of infections and acute or chronic graft-versus-host disease. Patients with inadequate lymphocyte recovery on Day +100 had worse overall survival and relapse-free survival and a higher cumulative incidence of relapse. CONCLUSION The evaluation of lymphocyte recovery on Day +30 is not a good predictor of relapse after transplant however patients with inadequate lymphocyte recovery had worse overall survival and relapse-free survival. Inadequate lymphocyte recovery on Day +100 is correlated with higher cumulative relapse as well as lower overall survival and relapse-free survival.