A seven-years experience in treatment of childhood ALL in Bulgaria.

After analyzing nonsatisfactory therapeutic results in the 1970s and early 1980s, the 81-01 treatment protocol of the Dana-Farber Cancer Institute was initiated in 1987 in the Children's Oncohaematology Clinic in Sofia, Bulgaria. Two hundred thirty patients were enrolled with a period of observation of a minimum of 14 and a maximum of 97 months; the median age was 5.83 +/- 3.6 years. According to the original criteria, standard risk (SR) patients were 38.26% and high-risk (HR) patients 61.74%. The probability for event-free survival at the seventh year estimated with the Kaplan-Meier method for the total group was 0.67 +/- 0.04 (+/- SE) and 0.55 +/- 0.09 and 0.81 +/- 0.06 for HR and SR, respectively (P < .001). Improvement of therapeutic results in terms of remission failures, early deaths, patients lost to follow-up, and rate of relapses is discussed.