Circulating blasts following chemotherapy in pediatric patients: implications for complete remission definition in acute leukemia.

We assessed the incidence of circulating blasts occurring post-chemotherapy in 1000 consecutive pediatric blood samples. Blasts with myeloid morphology (<1-3%) were present in post-chemotherapy samples in 19 of 294 (6.4%) patients with acute leukemia in remission and in 11 of 361 (3.4%) patients with solid tumors, non-Hodgkin or Hodgkin lymphoma, and were associated with ANC>1.5x10(9)/l in 13 of 30 (43%) samples, and platelets >100x10(9)/l in 25 of 30 (83%) samples. Our findings suggest that the absence of circulating blasts may not be a prerequisite for remission in acute myeloid leukemia (AML).