Diagnosis
The diagnosis of ALL and follow-up were performed based on bone marrow morphology only and required the presence of at least 25 % lymphoblasts. Bone marrow aspiration was performed under sterile conditions on the anterior superior iliac spine. Immunophenotyping and genetic analysis were not available. Further diagnostics included complete differential blood count and chemistry, cytospins of the cerebrospinal fluid, a chest x-ray, an abdominal ultrasound, an echocardiography and CT scan of the brain. Bone marrow examinations were performed on day 0/1, day 36 and week 32.