Related Experiment Videos
Acute Lymphoblastic Leukemia
Kun1
1Department of Radiation Oncology, St. Jude Children's Hospital, Memphis, TN, USA
Insights
Childhood acute lymphoblastic leukemia (ALL) treatment strategies vary by risk. Cranial irradiation (Crl) and high-dose methotrexate (MTX) are key for central nervous system (CNS) prevention and relapse control, though toxicities are debated.
Area of Science:
- Pediatric Oncology
- Hematology
- Cancer Therapeutics
Background:
- Acute lymphoblastic leukemia (ALL) is the most common childhood cancer, accounting for 25% of pediatric malignancies.
- Prognostic categories and therapeutic approaches for childhood ALL are determined by clinical and biological parameters.
- Risk stratification, including age and white blood cell (WBC) count, guides treatment intensity for B-progenitor and T-cell ALL.
Purpose of the Study:
- To outline current therapeutic regimens for childhood ALL, focusing on induction, consolidation, and continuation phases.
- To detail strategies for central nervous system (CNS) leukemia prevention and treatment, including intrathecal (IT) chemotherapy and cranial irradiation (Crl).
- To evaluate the efficacy and toxicities of different CNS prophylaxis and treatment modalities, particularly Crl versus intensive methotrexate-based regimens.
Main Methods:
- Review of current treatment protocols for childhood ALL, including chemotherapy regimens and CNS-directed therapies.
- Analysis of risk factors influencing treatment decisions, such as WBC count, age, immunophenotype, and specific chromosomal translocations.
- Examination of data on CNS relapse rates, outcomes of reinduction chemotherapy, and the impact of Crl and systemic methotrexate (MTX) on disease control and toxicity.
Main Results:
- High-dose systemic MTX has significantly reduced testicular relapse rates.
- Preventive CNS therapy, including IT chemotherapy and Crl, is critical for managing ALL.
- CNS relapse rates are approximately 5%, with reinduction and craniospinal irradiation achieving >60% control in isolated CNS relapse cases.
Conclusions:
- Overall disease-free survival for childhood ALL approaches 70% in contemporary series.
- Cranial irradiation (Crl) and intensive methotrexate-based regimens are effective but associated with distinct toxicities, including neurocognitive and neuroendocrine effects.
- The relative benefits and risks of Crl versus intensified MTX-based strategies for CNS prophylaxis and treatment in ALL remain a subject of ongoing research and clinical debate.
Abstract:
Acute lymphoblastic leukemia (ALL) accounts for 25% of childhood cancer. Clinical and biological parameters define prognostic categories and therapeutic approaches. For the majority of children with B-progenitor ALL, age (1-9 yrs) and white blood count (WBC<50,000) indicate standard risk disease; WBC>50,000 and age>9 yrs. define eligibility for high-risk protocols. Infants (<1 yr. old) are high-risk, frequently associated with chromosomal t(4;11) translocation and extramedullary disease. T-cell immunophenotype is usually associated with clinical high-risk features, including older age, high WBC, and extramedullary disease. T-cell immunophenotype is usually associated with clinical high-risk features, including older age, high WBC, and extramedullary disease. Current regimens include induction chemotherapy, consolidation (often including high-dose systemic methotrexate, MTX), and continuation phases; intensification or reinduction is incorporated for high-risk disease. Preventive CNS therapy is a critical component of therapy. Intrathecal (IT) chemotherapy (MTX +/- cytosine-arabinoside and hydrocortisone) and systemic agents provide adequate CNS therapy in standard risk patients. The "threshold" for using preventive cranial irradiation (Crl, 18 Gy) varies among protocols, but systematically includes those with T-cell ALL and WBS>50,000; other criteria may include B-progenitor ALL with WBC>100,000,philadelphia chromosome positive ALL, residual marrow disease at day 7, or male gender, For the 5% of children with CNS leukemia at diagnosis (defined as CSF with 5 or greater WBC/uL and positive cytology), Crl is administered at does of 18 to 24 Gy. Recent series show a CNS relapse rate approximating 5% Reinduction chemotherapy, IT therapy, and subsequent craniospinal irradiation ( typically 24, Gy Crl, 15 Gy spine) achieve durable secondary disease control in greater than 60% of cases with isolated CNS relapse. High-dose systemic MTX has virtually eliminated testicular relapse. CNS toxicities (including leukoencephalopathy) relate to systemic and IT MTX as well as Crl. Late neuropsychologicral data following Crl at 18 Gy show little intellectual deficit compared with children receiving MTX- based preventive therapy alone. Neuroendocrine dysfunction is apparent in long-term survivors following Crl at 24 Gy. The relative efficacy and toxicities of Crl versus more intensive MTX-based regimens are yet controversial. Overall disease-free survival in ALL approximates 70% in contemporary series.