Dose intensity (DI) plays an important role in the treatment of neoplastic diseases. The individual DI within a protocol may vary considerably and thus may be an important prognostic factor. In 213/305 patients treated in the cooperative study COALL-85 for childhood acute lymphoblastic leukemia the following parameters of individual therapy intensity were analyzed: Total time for intensive treatment, cumulative doses of single drugs, mean relative dose (= relation between received and prescribed doses of all drugs), mean relative dose intensity ( = mean relative dose/time) as well as frequency and duration of leukocytopenia. Therapy for LR (low-risk) and HR (high-risk) patients were separately analyzed by both life-table method and multivariate regression analysis. Neither length of time, mean relative dose intensity nor the other parameters had any significant influence on prognosis within the HR protocol. The only significant prognostic factor was the remission status on day 28 (p less than 0.001 in multivariate analysis). In contrast patients treated with the LR protocol had significantly fewer relapses if treatment resulted in leukocytopenic episodes (probability for event free survival (EFS) = 0.76 in patients with one or two leukocytopenic episodes compared to 0.52 in patients with none). Patients with a mean relative dose greater than 0.9 showed a higher EFS of borderline significance than patients with mean relative dose less than = 0.9 (0.72 vs 0.49, p = 0.09). We would like to conclude, that treatment protocols with very intensive and prolonged combination chemotherapy have a certain margin of safety in DI without disadvantage for the patient.(ABSTRACT TRUNCATED AT 250 WORDS)
