It should be noted that the final model was selected considering the type of tumor as an additional covariate (in addition to PB-CD34+) based on statistical information criterion (AIC), and that the tumor type was correlated with the age of the patients - the patients with Neuroblastoma tumor type, with mean age of 3.7 years (standard deviation, SD = 2.1 years), being younger than the others with mean age of 8.9 years (SD = 4.8 years). This evidence concerns the gene CD34 and neuroblastoma.