Effect of chemotherapy on circulating leukocyte counts.

(A) Initial leukocyte counts (leukemia burden) were similar among treatment arms, but within each treatment arm patients with T-lineage ALL (MP: n = 14; LDMTX plus MP: n = 13; HDMTX plus MP: n = 11) had higher leukocyte counts than those with B-lineage ALL (MP: n = 61; LDMTX plus MP: n = 70; HDMTX plus MP: n = 62;P < .001), and those with nonhyperdiploid B-lineage ALL (MP: n = 38; LDMTX plus MP: n = 44; HDMTX plus MP: n = 43) had higher leukocyte counts than those with hyperdiploid B-lineage ALL (MP: n = 23; LDMTX plus MP: n = 26; HDMTX plus MP: n = 19;P < .001). (B) Within each treatment arm, chemotherapeutic regimens produced significant decreases in circulating leukocyte counts (MP: n = 51; LDMTX plus MP: n = 77; HDMTX plus MP: n = 67) (P < .01), but the combination of MTX plus MP produced greater antileukemic effects than MP alone (P < .001). In patients randomized to receive MTX plus MP, those with T-lineage ALL (n = 22) had a greater percentage decrease in circulating leukocyte counts than those with B-lineage ALL (n = 121; P = .07), and those with nonhyperdiploid B-lineage ALL (n = 80) had a greater percentage decrease of leukocyte counts than those with hyperdiploid B-lineage ALL (n = 41;P < .01).