Unfavorable prognosis of acute leukemia in infancy.

Pretreatment characteristics of 48 infants (under 2 years of age) with leukemia treated over a period of 18 years at a single institution were studied in relation to response to therapy, extramedullary involvement, and survival. In order to provide a basis of comparison, 45 of the infants were each paired with an older (2-9 years of age) leukemic child, who had the same race, and disease type, who was treated within the same period of time and received similar suportive care and chemotherapy, and when possible, was of the same sex. The overall median survival times of infants and their pairmates were 211 days and 445 days, respectively. Initial status of the spleen was the single significant factor in relation to the length of survival. Median survival time for infants with splenomegaly was 186 days compared to a median survival time of 414 days for infants without splenomegaly. The complete response rate was 75% for infants and 80% for the pairmates. Median duration of remission was 84 days for infants and 280 days for their pairmates. Initial peripheral leucocyte count was significantly related to the duration of remission; patients with very high leucocyte counts had the shortest remissions. The duration of remission increased throughout the period covered by this study, however, prognosis relative to pairmates remained poor. Central nervous system leukemia occurred in 44% of infants and 40% of the pairmates; incidence of CNS leukemia was much higher (70%) in infants under one year of age than in infants one year old (37%). Extramedullary leukemia occurred at other sites in 46% of the infants and 31% of the pairmates. The only pretreatment characteristic of prognostic importance for predicting extramedullary involvement was the patient's age at diagnosis.