The absence of peripheral blood blasts at diagnosis may predict CNS involvement or CNS relapse in pediatric acute lymphoblastic leukemia patients

A high tumor burden at the time of diagnosis of childhood acute lymphoblastic leukemia has an unfavorable outcome. Peripheral white blood cell count is commonly used to reflect the leukemic burden and is used as one of the most important factors during determination of the risk-based treatment. However, peripheral blood blast count may not always reflect the tumor burden if leukocytes are not in blast nature. In the present study, we observed no central nervous system involvement at the time of diagnosis in patients with no peripheral blood blasts at the beginning, and furthermore, none of the patients with no peripheral blasts at the diagnosis had central nervous system relapse.