Prognostic significance of vacuoles in L1 lymphoblasts in childhood acute lymphoblastic leukaemia: a report from Children's Cancer Study Group.

From February 1975 to February 1977, 880 patients with acute lymphoblastic leukaemia were enrolled on Children's Cancer Study Group protocol 141 designed to evaluate prognostic factors and more intensive therapy for patients with poor prognosis. 765 diagnostic bone marrow aspirates from 23 institutions were available for classification using the French-American-British system. 60 of 615 patients with L1 morphology had vacuolated lymphoblasts. Patients with vacuolated lymphoblasts had a better disease-free survival (P = 0.14) and a significantly better survival (P = 0.03) but the presence of vacuoles was associated with a low initial WBC and an age range associated with improved prognosis for disease-free and over-all survival.