Cure rates of childhood acute lymphoblastic leukemia in Lithuania and the benefit of joining international treatment protocol

Background: Childhood acute lymphoblastic leukemia (ALL) represents the largest group of pediatric malignancies with long-term survival rates of more than 80% achieved in developed countries. Epidemiological data and survival rates of childhood ALL in Lithuania were lacking. Therefore, the aim of this study was to analyze the population-based long-term treatment results of childhood ALL in Lithuania during 1992–2012.
Materials and methods: Data of all 459 children with T-lineage and B-cell precursor ALL treated in Lithuania from 1992 to 2012 were collected and analyzed. Results were compared among four time-periods: 1992–1996 (N = 132), 1997–2002 (N = 136), 2003–2008 (N = 109) and 2009–2012 (N = 82).
Results: The incidence of childhood ALL in Lithuania was 3.2–3.6 cases per 100 000 children per year during the study period. Five-year probability of event-free survival increased from 50% 4% in 1992–1996 to 71% ± 4% in 2003–2008 (P < 0.001). Five-year cumulative incidence of relapses reduced from 27% ± 4.5% in 1992–1996 to 14% ± 3.6% in 2003–2008 (P = 0.042). After introduction of high-dose methotrexate of 5 g/m2, cumulative incidence of CNSinvolving relapses reduced from 17% ± 3.9% in 1992–1996 to 1% ± 1.0% in 2003–2008 (P < 0.001). Trend for further improvement in survival was seen in 2009–2012 when Lithuania joined international the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL-2008 treatment protocol.
Conclusions: Cure rates of childhood ALL in Lithuania are improving steadily and are now approaching those reported by the largest international study groups. The reasons for such a positive effect are both better financial support for treatment of children with cancer in Lithuania and international collaboration with joining international treatment protocol for childhood ALL.