Risk Factors in Childhood Acute Lymphoblastic Leukemia: A Single Center Experience in a Developing Country.

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy, with the survival rates up to 80–90%, but in high-risk patients the survival rate is still unsatisfactory. The aim of this study is to analyze the pediatric ALL data of a single pediatric university center between 1987–2005 retrospectively to identify risk factors effecting the event free survival (EFS). In order to determine the risk factors possibly effecting the survival, we analyzed gender, age, physical examination findings, blood cell count, FAB morphology, immunophenotyping results, translocations and extramedullary involvement. During the same period, chemotherapy regimens used and response to these protocols were also analyzed. A total of 372 cases [220 male (60%) and 151 female (41%)] were diagnosed and treated in our center between 1987–2005. The age distribution was as follows: 7% patients under 2 years, 68% between 2–10 years, 25% above 10 years of age. At diagnosis, 76% patients had a hemoglobin level <10gr/dl, 56% WBC >10.000/mm3, 74% platelet <100.000/mm3. Primary CNS involvement was positive in 2.5%, mediastinal mass in 8% of all patients. The morphological subtypes were as follows: L1 64%, L2 32%, L3 4%. Immunophenotypic results revealed T ALL in 22%, mature B ALL in 8% and B ALL (common, pre B, proB) in 70%. All patients received CCG modified BFM protocol (80% of all patients) until 1999. Since then high-risk patients were treated with the augmented BFM protocol and L3 patients BFM NHL 95 Protocol, while standard risk patients continued to get the CCG modified BFM protocol. The remission rate at day 33 was 97.8%. Eighty-one patients relapsed (68% patients isolated bone marrow, 16% bone marrow + extramedullary, 9% CNS, 7% testes). According to the univariate analysis of our patient population, the factors negatively effecting the EFS were age <1 year, hepatomegaly >2cm., white blood cell >50.000/mm3 and platelet count <20.000/mm3, L3 FAB morphology, ≥M2 bone marrow status at day 14; CD3, HLADR, CD45 and Tdt negativity. According to the multivariate analysis the most important negative risk factors effecting the EFS were age <1 year, hepatomegaly >2cm. and ≥M2 bone marrow status at day 14 and CD 45 negativity. After a follow up of 72±59 months (1–300 months) 58% of patients are alive & well, 28% were lost to follow up and 14% patients succumbed to death. Overall survival (OS) for 60&120 months follow up were 83%, 83% and event free survival (EFS) 72%, 70% respectively. In conclusion, in ALL patients risk assessment is very important to conduct appropriate therapy. Identifying such factors and implementing risk adapted therapy will improve our treatment results decreasing the toxicity rates in pediatric ALL. Therefore treatment of all ALL patients still remains a challenge.