Lack of influence of T-cell marker and importance of mediastinal mass on the prognosis of acute lymphocytic leukemias of childhood.

One hundred consecutive new cases of acute lymphocytic leukemia (ALL) were studied in patients that were 4 months to 16 years of age when admitted to The Children's Hospital of Philadelphia. Various prognostic factors were examined and related to the duration of the first remission. These factors included lymphoblast surface markers, age at diagnosis, sex, race, initial white blood counts (WBC), presence of mediastinal mass, degree of hepatosplenomegaly, and lymph node size. Classification by lymphoblast surface markers showed 22 T-cell, 71 null cell, and 3 B-cell leukemias; 3 cases were unclassifiable and 1 had both T- and B-cell markers. Statistical analysis indicated that stratification by presence or absence of mediastinal mass was necessary. Most patients with mediastinal masses, 5 of thymus and 4 of the non-thymus type, fared poorly with a median duration of continuous complete remission of less than 12 months as compared with greater than 48 months for those without such masses. The most satisfactory model to estimate remission duration in children without mediastinal masses was dependent upon initial WBC, sex, race, and surface markers. Low WBC, white race, female sex, and T-cell markers in patients without mediastinal masses were associated with a favorable prognosis. The findings suggest that patients with mediastinal masses need special therapy and that T-cell ALL without a mediastinal masses need special therapy and that T-cell ALL without a mediastinal mass does not carry a poorer prognosis than does null cell ALL.