White cell count during maintenance chemotherapy for standard-risk childhood acute lymphoblastic leukemia: relation to relapse rate.

In a retrospective study of 84 children with standard-risk acute lymphoblastic leukemia diagnosed in 1981-1986, mean white cell count (mWBC) during maintenance chemotherapy (MT) was found to be significantly related to risk of hematological relapse, giving patients with the higher mWBC the poorer outcome. The only other significant relapse-related risk factor was white-cell count at diagnosis. mWBC was not significantly related to white cell count at diagnosis, sex, age, or dose of methotrexate or mercaptopurine. Patients with low mWBC also had relatively low white-cell counts after cessation of therapy when compared with patients with high mWBC.