Prognostic factor analysis in acute lymphocytic leukemia of childhood.

The analysis of clinical and hematological data for prognostic relevance in 200 children with acute lymphocytic leukemia (ALL), diagnosed between January 1964 and December 1980, showed that the importance of single risk factors has changed due to improvements in therapy. Morphology and cytochemistry lost their prognostic value they had in those patients treated before October 1971. In the children treated in the seventies, the WBC became the most important prognostic factor, followed by infiltrate size and age. (Age was less important than infiltrates for remission duration, but more for survival.) Immunological markers were evaluated in 56 children, since 1974. Because of the small number, no significance as risk factor was found. Those 25% with E+ blasts tended to have only a slightly worse course than "non-T-non-B"-ALL. Treatment became a highly significant risk factor, because of the improvement in results between those patients treated with CALGB protocol 6801 and those on protocol 7111. Two steps were responsible for this: better treatment strategies, and, most important, CNS-prophylaxis (or "sanctuary"-treatment) in all patients. Even in the sixties, where IT methotrexate alone was given sporadically, omitting the CNS-prophylaxis represented an important risk factor. Since 1971, most patients received cranial irradiation or intermediate dose methotrexate as second mode of CNS-prophylaxis. This resulted in a significant decrease in the incidence of CNS relapse. CNS-prophylaxis mode therefore represented a significant prognostic factor, although age, WBC and infiltrates had become more important. Evaluation of the clinical and hematological data gave the following limits for an increased or lesser risk: WBC over 30.G/l: high risk, under 10.G/l: favourable. Age: below 1 year and over 10 years: high risk, 1-2 years: probably moderately increased risk. Infiltrates: no palpable hepatosplenomegaly and no lymph nodes: favourable, all palpable infiltrates: "standard" or increased risk. Platelets (under 30.G/l) represented a minor good risk factor. The common ALL antigen (CALLA) was not yet examined in this series, calling it a favourable factor is based on recent experience from other centers. T-markers are probably not a risk factor by themselves, but other poor prognostic signs are usually associated and of primary importance. If treatment will be based on risk classification, it is important to keep in mind that treatment improvements might change the significance of any prognostic factor completely.