Absolute lymphocyte count at the end of induction therapy is a prognostic factor in childhood acute lymphoblastic leukemia.

Recent studies have reported that the absolute lymphocyte count (ALC) during induction therapy is predictive of treatment outcome in de novo acute lymphoblastic leukemia (ALL); however, the significance of ALC on outcomes remains controversial. In the present study, we assessed the significance of ALC at day 29 (ALC-29), the end of induction therapy, on outcomes in our Japanese cohort. The outcomes of 141 patients aged ≤18 years with newly diagnosed ALL who were enrolled on the JACLS ALL-02 at our hospitals were analyzed in terms of ALC-29. Patients with ALC-29 ≥750/μL (n = 81) had a superior 5-year EFS (95.2 ± 2.7 vs 84.3 ± 4.8 %, P = 0.016) and OS (100 vs 87.0 ± 4.7 %, P = 0.0062). A multivariate analysis identified ALC-29 ≥750/μL as a significant predictor of improved EFS and OS after controlling for confounding factors. A multiple linear regression model revealed a significant inverse relationship between the percentage of blasts in bone marrow on day 15 and ALC-29 (P = 0.005). These results indicate that ALC is a simple prognostic factor in childhood ALL, and, thus, has the potential to refine current risk algorithms.