The effect of absolute lymphocyte count recovery kinetics on survival after autologous stem cell transplantation for non-Hodgkin's lymphoma

Absolute lymphocyte count (ALC) ≥ 500 cells/μl at day 15 after autologous stem cell transplantation (ASCT) is a powerful independent, prognostic indicator for survival in multiple hematological malignancies. A limitation in these studies was the selection of a single time point (day 15 post-ASCT) as the only discriminator of clinical outcome in relation to ALC recovery. We hypothesized there is a continuous and not discrete relationship between ALC recovery and clinical outcome post-ASCT in NHL. Therefore, we analyzed 274 consecutive patients who underwent ASCT for NHL between 1987 and 2001. The primary end point was to assess the impact of the kinetics of post-ASCT lymphocyte recovery ≥ 500 cells/μl (K-ALC) on overall survival (OS) and progression-free survival (PFS). K-ALC was a predictor of OS and PFS when the Cox proportional hazards model was used with K-ALC entered as a continuous variable (p < 0.0001). Multivariate analysis demonstrated K-ALC recovery post-ASCT to be an independent prognostic indicator for OS and PFS. These data support our hypothesis that the K-ALC post-ASCT is associated with clinical outcome in NHL.