Background
Prospective institutional study (St. Jude Total Therapy Study XV). 498 children with newly diagnosed ALL treated 2000–2007. First large prospective study to demonstrate that ALL can be treated to high survival rates with complete elimination of prophylactic cranial RT for all patients, including high-risk groups, using risk-adapted chemotherapy with intensive intrathecal therapy and optional bone marrow transplant for very high-risk patients.
Interventions and follow up
Arm A: Risk-adapted chemotherapy (low-, standard-, high-risk strata) with intensive intrathecal chemotherapy (MTX ± ARA-C ± hydrocortisone) — no prophylactic cranial RT for any patient; transplant for very high-risk patient
Primary endpoint: EFS, OS, CNS relapse rate
mFollow up: 6.0 year
Primary endpoint: EFS, OS, CNS relapse rate
mFollow up: 6.0 year
Results
5-yr EFS: 85.6% (low risk), 80.3% (standard risk), 67.2% (high risk)
5-yr OS: 93.7% (low risk), 90.0% (standard risk), 75.3% (high risk)
CNS relapse (no prophylactic CRT): 2.7% — no excess vs historical cranial RT cohorts
Neurocognitive outcomes: Significantly better than historical patients who received cranial RT
5-yr OS: 93.7% (low risk), 90.0% (standard risk), 75.3% (high risk)
CNS relapse (no prophylactic CRT): 2.7% — no excess vs historical cranial RT cohorts
Neurocognitive outcomes: Significantly better than historical patients who received cranial RT
Adverse events
Main adverse events: No cranial RT-related neurotoxicity. Intensive intrathecal chemo: chemical arachnoiditis (15%), rare leukoencephalopathy. High-risk chemo: myelosuppression, infection, pegaspargase allergy/pancreatitis. Osteonecrosis: 11% in adolescents on dexamethasone.
Conclusions
Prophylactic cranial RT can be completely eliminated in childhood ALL treatment using modern risk-adapted intensive chemotherapy with intrathecal therapy, with preserved CNS control and superior neurocognitive outcomes. This landmark study fundamentally changed the global standard for ALL treatment.
Key Limitations
Key Limitations: Single-institution; potential for selection bias and expertise-dependent outcomes. Very high-risk patients received stem cell transplantation — not widely applicable. Molecular characterization (ETV6-RUNX1, BCR-ABL1-like ALL) not incorporated into risk stratification in this era.
Clinical Context
Total Therapy XV established the proof-of-concept and real-world evidence base for eliminating prophylactic cranial RT from all childhood ALL treatment. This approach has been adopted worldwide. Current NCCN, COG, and ESMO guidelines do not include prophylactic cranial RT for newly diagnosed ALL in any risk group.
References