CNS-Directed Therapy for Childhood ALL
CNS-Penetrant Systemic Chemotherapy
CNS Therapy for Standard-Risk Patients
CNS Therapy for High-Risk Patients
Toxicity of CNS-Directed Therapy
Presymptomatic CNS Therapy Options Under Clinical Evaluation
CNS Therapy for Patients With CNS Involvement (CNS3 Disease) at Diagnosis
Successful treatment of children with acute lymphoblastic leukemia (ALL) requires the control of systemic disease (e.g., marrow, liver and spleen, lymph nodes), and the prevention or treatment of extramedullary disease, particularly in the central nervous system (CNS).
Approximately 3% of patients have detectable CNS involvement by conventional criteria at diagnosis (cerebrospinal fluid [CSF] specimen with ≥5 white blood cell [WBC]/μL with lymphoblasts and/or the presence of cranial nerve palsies). However, unless specific therapy is directed toward the CNS, the majority of children will eventually develop overt CNS leukemia. Therefore, all children with ALL should receive systemic combination chemotherapy together with some form of CNS prophylaxis.
Historically, survival rates for children with ALL did not improve until CNS-directed therapy was instituted. The early institution of adequate CNS therapy is critical for eliminating clinically evident CNS disease at diagnosis and for preventing CNS relapse in all patients. Standard treatment options for CNS-directed therapy include the following:
The type of CNS-therapy that is used is based on a patient’s risk of CNS-relapse, with higher-risk patients receiving more intensive treatments. Data suggest that the following groups of patients are at increased risk of CNS relapse:
- Patients with blasts in the CSF but fewer than 5 WBC/µL (CNS2) are at increased risk of CNS relapse, although this risk appears to be nearly fully abrogated if they receive more intensive intrathecal chemotherapy, especially during the induction phase.
- Patients who have a traumatic lumbar puncture showing blasts at the time of diagnosis have an increased risk of CNS relapse, and these patients receive more intensive CNS-directed therapy on some treatment protocols.[2,3]
CNS-directed treatment regimens for newly diagnosed childhood ALL are presented in Table 2:Table 2. CNS-Directed Treatment Regimens for Newly Diagnosed Childhood ALL
|Disease Status||Standard Treatment Options|
|ALL = acute lymphoblastic leukemia; CNS = central nervous system; CNS3 = cerebrospinal fluid with 5 or more white blood cells/µL and cytospin positive for blasts.|
|Standard-risk ALL||Intrathecal chemotherapy|
|Methotrexate with cytarabine and hydrocortisone|
|CNS-penetrant systemic chemotherapy|
|High-dose methotrexate with leucovorin rescue|
|High-risk ALL||Intrathecal chemotherapy|
|Methotrexate with cytarabine and hydrocortisone|
|CNS-penetrant systemic chemotherapy|
|High-dose methotrexate with leucovorin rescue|
A major goal of current ALL clinical trials is to provide effective CNS therapy while minimizing neurologic toxic effects and other late effects.Intrathecal Chemotherapy
All therapeutic regimens for childhood ALL include intrathecal chemotherapy. Intrathecal chemotherapy is usually started at the beginning of induction, intensified during consolidation (four to eight doses of intrathecal chemotherapy given every 2–3 weeks), and, in certain protocols, continued throughout the maintenance phase.
Intrathecal chemotherapy typically consists of one of the following:
- Methotrexate alone.
- Methotrexate with cytarabine and hydrocortisone.
Unlike intrathecal cytarabine, intrathecal methotrexate has a significant systemic effect, which may contribute to prevention of marrow relapse.CNS-Penetrant Systemic Chemotherapy
In addition to therapy delivered directly to the brain and spinal fluid, systemically administered agents are also an important component of effective CNS prophylaxis. The following systemically administered drugs provide some degree of CNS prophylaxis:
- High-dose methotrexate with leucovorin rescue.
Evidence (CNS-penetrant systemic chemotherapy):
- In a randomized Children's Cancer Group (CCG) study of standard-risk patients who all received the same dose and schedule of intrathecal methotrexate without cranial irradiation, oral dexamethasone was associated with a 50% decrease in the rate of CNS relapse compared with oral prednisone.
- In a standard-risk ALL trial (COG-1991), lower-dose intravenous methotrexate without rescue significantly reduced the CNS relapse rate compared with oral methotrexate given during each of two interim maintenance phases.
- In a randomized clinical trial conducted by the Pediatric Oncology Group, T-cell ALL patients who received high-dose methotrexate experienced a significantly lower CNS relapse rate than patients who did not receive high-dose methotrexate.
The proportion of patients receiving cranial radiation has decreased significantly over time. At present, most newly diagnosed children with ALL are treated without cranial radiation. Many groups administer cranial radiation only to those patients considered to be at highest risk for subsequent CNS relapse, such as those with documented CNS leukemia at diagnosis (as defined above) (>5 WBC/μL with blasts; CNS3) and/or T-cell phenotype with high presenting WBC count. In patients still receiving cranial radiation, the dose has been significantly reduced.
Ongoing trials seek to determine whether radiation can be eliminated from the treatment of all children with ALL without compromising survival or leading to increased rate of toxicities from upfront and salvage therapies.[10,11]CNS Therapy for Standard-Risk Patients
Evidence (triple intrathecal chemotherapy vs. intrathecal methotrexate):
- The CCG-1952 study for National Cancer Institute (NCI) standard-risk patients compared the relative efficacy and toxicity of triple intrathecal chemotherapy (methotrexate, prednisone, and cytarabine) with methotrexate as the sole intrathecal agent in nonirradiated patients.
- There was no significant difference in either CNS or non-CNS toxicities.
- Triple intrathecal chemotherapy was associated with a lower rate of isolated CNS relapse (3.4% ± 1.0% compared with 5.9% ± 1.2% for intrathecal methotrexate; P = .004).
- This effect was especially notable in patients with CNS2 status at diagnosis (lymphoblasts seen in CSF cytospin, but with <5 WBC/high-power field [hpf] on CSF cell count); the isolated CNS relapse rate was 7.7% ± 5.3% for CNS2 patients who received triple intrathecal chemotherapy compared with 23.0% ± 9.5% for those who received intrathecal methotrexate alone (P = .04).
- There were more bone marrow relapses in the group that received the triple intrathecal chemotherapy, leading to a worse overall survival (OS) (90.3% ± 1.5%) compared with the intrathecal methotrexate group (94.4% ± 1.1%; P = .01).
- When the analysis was restricted to patients with precursor B-cell ALL and rapid early response (M1 marrow on day 14), there was no difference between triple and single intrathecal chemotherapy in terms of rates of CNS relapse rate, OS, or event-free survival (EFS).
- In a follow-up study of neurocognitive functioning in the two groups, there were no clinically significant differences.[Level of evidence: 1iiC]
Controversy exists as to which high-risk patients should be treated with cranial radiation. Depending on the protocol, up to 20% of children with ALL receive cranial radiation as part of their CNS-directed therapy, even if they present without CNS involvement at diagnosis. Patients receiving cranial radiation on many treatment regimens include the following:
- Patients with T-cell phenotype and high initial WBC count.
- Patients with high-risk precursor B-cell ALL (e.g., extremely high presenting leukocyte counts and/or adverse cytogenetic abnormalities).
Both the proportion of patients receiving radiation and the dose of radiation administered have decreased over the last 2 decades.
Evidence (cranial radiation):
- In a trial conducted between 1990 and 1995, the Berlin-Frankfurt-Münster (BFM) group demonstrated that a reduced dose of prophylactic radiation (12 Gy instead of 18 Gy) provided effective CNS prophylaxis in high-risk patients.
- In the follow-up trial conducted by the BFM group between 1995 and 2000 (BFM-95), cranial radiation was administered to approximately 20% of patients (compared with 70% on the previous trial), including patients with T-cell phenotype, a slow early response (as measured by peripheral blood blast count after a 1-week steroid prophase), and/or adverse cytogenetic abnormalities.
- While the rate of isolated CNS relapses was higher in the nonirradiated higher-risk patients compared with historic (irradiated) cohorts, their overall EFS rate was not significantly different.
- Several groups, including the St. Jude Children's Research Hospital (SJCRH), the Dutch Childhood Oncology Group (DCOG), and the European Organization for Research and Treatment of Cancer (EORTC), have published results of trials that omitted cranial radiation for all patients, including high-risk subsets.[10,11,21] Most of these trials have included at least four doses of high-dose methotrexate during postinduction consolidation and an increased frequency of intrathecal chemotherapy. The SJCRH and DCOG studies also included frequent vincristine/dexamethasone pulses during the first 1 to 2 years of therapy,[10,11] while the EORTC trials included additional high-dose methotrexate and multiple doses of high-dose cytarabine, during postinduction treatment phases for CNS3 (CSF with ≥5 WBC/µL and cytospin positive for blasts) patients.
- The 5-year cumulative incidence of isolated CNS relapse on those trials was between 2% and 4%, although some patient subsets had a significantly higher rate of CNS relapse. On the SJCRH study, clinical features associated with a significantly higher risk of isolated CNS relapse included T-cell phenotype, the t(1;19) translocation, or the presence of blasts in the CSF at diagnosis.
- The overall EFS for the SJCRH study was 85.6% and 81% for the DCOG study, both in line with outcomes achieved by contemporaneously conducted clinical trials on which some patients received prophylactic radiation, but was lower on the EORTC trial (8-year EFS, 69.6%).
- Of note, on the SJCRH study, 33 of 498 (6.6%) patients in first remission with high-risk features (including 26 with high minimal residual disease, six with Philadelphia chromosome-positive ALL, and one with near haploidy) received an allogeneic stem cell transplant (SCT), which included total-body irradiation.
Toxic effects of CNS-directed therapy for childhood ALL can be divided into the following two broad groups:
- Acute/subacute toxicities (e.g., seizures, stroke, somnolence syndrome, and ascending paralysis).
- Late-developing toxicities (e.g., meningiomas and other second neoplasms; leukoencephalopathy; and a range of neurocognitive, behavioral, and neuroendocrine disturbances).[22-24]
The most common acute side effect associated with intrathecal chemotherapy alone is seizures. Up to 5% of nonirradiated patients with ALL treated with frequent doses of intrathecal chemotherapy will have at least one seizure during therapy. Higher rates of seizure were observed with consolidation regimens that included multiple doses of high-dose methotrexate in addition to intrathecal chemotherapy.
Patients with ALL who develop seizures during the course of treatment and who receive anticonvulsant therapy should not receive phenobarbital or phenytoin as anticonvulsant treatment, as these drugs may increase the clearance of some chemotherapeutic drugs and adversely affect treatment outcome. Gabapentin or valproic acid are alternative anticonvulsants with less enzyme-inducing capabilities.Late-developing toxicities
In general, patients who receive intrathecal chemotherapy without cranial radiation appear to have less severe neurocognitive sequelae than irradiated patients, and the deficits that do develop represent relatively modest declines in a limited number of domains of neuropsychological functioning.[27-30] This modest decline is primarily seen in young children and girls.
Controversy exists about whether patients who receive dexamethasone are at higher risk for neurocognitive disturbances. Long-term neurocognitive testing in 92 children with a history of standard-risk ALL who had received either dexamethasone or prednisone during treatment did not demonstrate any meaningful differences in cognitive functioning based on corticosteroid randomization.
Long-term deleterious effects of cranial radiation, particularly at doses higher than 18 Gy, have been recognized for years. Children receiving these higher doses of cranial radiation are at significant risk of neurocognitive and neuroendocrine sequelae.[34-38]
The following groups have been associated with neurocognitive and neuroendocrine sequelae following cranial radiation:
- Young children (i.e., younger than 4 years) are at increased risk of neurocognitive decline and other sequelae following cranial radiation.[39-41]
- Girls may be at a higher risk than boys of radiation-induced neuropsychologic and neuroendocrine sequelae.[40-42]
- Long-term survivors treated with 18 Gy radiation appear to have less severe neurocognitive sequelae than those who had received higher doses of radiation (24–28 Gy) on clinical trials conducted in the 1970s and 1980s.
Evidence (toxicity of cranial radiation):
- In a randomized trial, hyperfractionated radiation (at a dose of 18 Gy) did not decrease neurologic late effects when compared with conventionally fractionated radiation; cognitive function for both groups was not significantly impaired.; [Level of evidence: 1iiC]
- On current clinical trials, many patients who receive prophylactic or presymptomatic cranial radiation are treated with an even lower dose (12 Gy). Longer follow-up is needed to determine whether 12 Gy will be associated with a lower incidence of neurologic sequelae.
Cranial radiation has also been associated with an increased risk of second neoplasms, many of which are benign or of low malignant potential, such as meningiomas.[24,45,46] Leukoencephalopathy has been observed after cranial radiation in children with ALL, but appears to be more common with higher doses than are currently administered. In general, systemic methotrexate doses greater than 1 g/m2 should not be given following cranial radiation because of the increased risk of neurologic sequelae, including leukoencephalopathy.Presymptomatic CNS Therapy Options Under Clinical Evaluation
Treatment options under clinical evaluation include the following:
- COG-AALL0434 (NCT00408005) (Combination Chemotherapy in Treating Young Patients With Newly Diagnosed T-Cell ALL or T-cell Lymphoblastic Lymphoma): In the Children’s Oncology Group (COG) COG-AALL0434 protocol for patients with T-cell ALL, low-risk T-cell patients (those with NCI standard-risk features and a rapid response to induction therapy) are treated without cranial radiation, and intermediate-risk T-cell patients receive 12 Gy (instead of 18 Gy) cranial radiation. High-risk T-cell patients continue to receive 18 Gy cranial radiation. All patients are randomly assigned to receive either high-dose methotrexate (5 g/m2 over 24 hours) with leucovorin rescue or escalating-dose methotrexate without leucovorin rescue during the initial interim maintenance phase of therapy.
- COG-AALL1131 (Combination Chemotherapy in Treating Young Patients With Newly Diagnosed High-Risk ALL): The COG-AALL1131 protocol for patients with high-risk B-precursor ALL includes a randomized comparison of intrathecal triple chemotherapy (methotrexate, cytarabine, and hydrocortisone) with intrathecal methotrexate, with the objective of determining whether intrathecal triple chemotherapy reduces CNS-relapse rates and improves overall EFS. Only patients with CNS3 status at diagnosis will receive cranial radiation (18 Gy). Patients with induction failure or low hypodiploidy are eligible for allogeneic SCT in first remission.
- SJCRH Total XVI (TOTXVI) (Total Therapy Study XVI for Newly Diagnosed Patients With ALL): Patients receive both intrathecal chemotherapy and high-dose methotrexate without radiation therapy. Certain patients with high-risk features, including those with a t(1;19) translocation, receive intensified intrathecal therapy.
Therapy for ALL patients with clinically evident CNS disease (>5 WBC/hpf with blasts on cytospin; CNS3) at diagnosis typically includes intrathecal chemotherapy and cranial radiation (usual dose is 18 Gy).[15,17] Spinal radiation is no longer used.
Evidence (cranial radiation):
- On the SJCRH Total XV (TOTXV) study, patients with CNS3 status (N = 9) were treated without cranial radiation (observed 5-year EFS, 43% ± 23%). On this study, CNS-leukemia at diagnosis (defined as CNS3 status or traumatic lumbar puncture with blasts) was an independent predictor of inferior EFS.
- On the DCOG-9 trial, the 5-year EFS of CNS3 patients (N = 21) treated without cranial radiation was 67% ± 10%.
- SJCRH and the EORTC have published results of trials that omitted cranial radiation for all patients, including high-risk subsets.[10,21] These trials have included at least four doses of high-dose methotrexate during postinduction consolidation and an increased frequency of intrathecal chemotherapy. The SJCRH study also included frequent vincristine/dexamethasone pulses during the first 1 to 2 years of therapy,, while the EORTC trials included additional high-dose methotrexate and multiple doses of high-dose cytarabine, during postinduction treatment phases for CNS3 (CSF with ≥5 WBC/µL and cytospin positive for blasts) patients.
- The long-term EFS for CNS3 patients on these trials ranged from 43% (SJCRH) to 68% (EORTC).
Larger studies will be necessary to fully elucidate the safety of omitting cranial radiation in CNS3 patients.References
- Mahmoud HH, Rivera GK, Hancock ML, et al.: Low leukocyte counts with blast cells in cerebrospinal fluid of children with newly diagnosed acute lymphoblastic leukemia. N Engl J Med 329 (5): 314-9, 1993. [PUBMED Abstract]
- Bürger B, Zimmermann M, Mann G, et al.: Diagnostic cerebrospinal fluid examination in children with acute lymphoblastic leukemia: significance of low leukocyte counts with blasts or traumatic lumbar puncture. J Clin Oncol 21 (2): 184-8, 2003. [PUBMED Abstract]
- Gajjar A, Harrison PL, Sandlund JT, et al.: Traumatic lumbar puncture at diagnosis adversely affects outcome in childhood acute lymphoblastic leukemia. Blood 96 (10): 3381-4, 2000. [PUBMED Abstract]
- Pullen J, Boyett J, Shuster J, et al.: Extended triple intrathecal chemotherapy trial for prevention of CNS relapse in good-risk and poor-risk patients with B-progenitor acute lymphoblastic leukemia: a Pediatric Oncology Group study. J Clin Oncol 11 (5): 839-49, 1993. [PUBMED Abstract]
- Thyss A, Suciu S, Bertrand Y, et al.: Systemic effect of intrathecal methotrexate during the initial phase of treatment of childhood acute lymphoblastic leukemia. The European Organization for Research and Treatment of Cancer Children's Leukemia Cooperative Group. J Clin Oncol 15 (5): 1824-30, 1997. [PUBMED Abstract]
- Bostrom BC, Sensel MR, Sather HN, et al.: Dexamethasone versus prednisone and daily oral versus weekly intravenous mercaptopurine for patients with standard-risk acute lymphoblastic leukemia: a report from the Children's Cancer Group. Blood 101 (10): 3809-17, 2003. [PUBMED Abstract]
- Matloub Y, Bostrom BC, Hunger SP, et al.: Escalating intravenous methotrexate improves event-free survival in children with standard-risk acute lymphoblastic leukemia: a report from the Children's Oncology Group. Blood 118 (2): 243-51, 2011. [PUBMED Abstract]
- Asselin BL, Devidas M, Wang C, et al.: Effectiveness of high-dose methotrexate in T-cell lymphoblastic leukemia and advanced-stage lymphoblastic lymphoma: a randomized study by the Children's Oncology Group (POG 9404). Blood 118 (4): 874-83, 2011. [PUBMED Abstract]
- Pui CH, Howard SC: Current management and challenges of malignant disease in the CNS in paediatric leukaemia. Lancet Oncol 9 (3): 257-68, 2008. [PUBMED Abstract]
- Pui CH, Campana D, Pei D, et al.: Treating childhood acute lymphoblastic leukemia without cranial irradiation. N Engl J Med 360 (26): 2730-41, 2009. [PUBMED Abstract]
- Veerman AJ, Kamps WA, van den Berg H, et al.: Dexamethasone-based therapy for childhood acute lymphoblastic leukaemia: results of the prospective Dutch Childhood Oncology Group (DCOG) protocol ALL-9 (1997-2004). Lancet Oncol 10 (10): 957-66, 2009. [PUBMED Abstract]
- Pui CH, Sandlund JT, Pei D, et al.: Improved outcome for children with acute lymphoblastic leukemia: results of Total Therapy Study XIIIB at St Jude Children's Research Hospital. Blood 104 (9): 2690-6, 2004. [PUBMED Abstract]
- Tubergen DG, Gilchrist GS, O'Brien RT, et al.: Prevention of CNS disease in intermediate-risk acute lymphoblastic leukemia: comparison of cranial radiation and intrathecal methotrexate and the importance of systemic therapy: a Childrens Cancer Group report. J Clin Oncol 11 (3): 520-6, 1993. [PUBMED Abstract]
- Conter V, Aricò M, Valsecchi MG, et al.: Extended intrathecal methotrexate may replace cranial irradiation for prevention of CNS relapse in children with intermediate-risk acute lymphoblastic leukemia treated with Berlin-Frankfurt-Münster-based intensive chemotherapy. The Associazione Italiana di Ematologia ed Oncologia Pediatrica. J Clin Oncol 13 (10): 2497-502, 1995. [PUBMED Abstract]
- Möricke A, Reiter A, Zimmermann M, et al.: Risk-adjusted therapy of acute lymphoblastic leukemia can decrease treatment burden and improve survival: treatment results of 2169 unselected pediatric and adolescent patients enrolled in the trial ALL-BFM 95. Blood 111 (9): 4477-89, 2008. [PUBMED Abstract]
- Clarke M, Gaynon P, Hann I, et al.: CNS-directed therapy for childhood acute lymphoblastic leukemia: Childhood ALL Collaborative Group overview of 43 randomized trials. J Clin Oncol 21 (9): 1798-809, 2003. [PUBMED Abstract]
- Moghrabi A, Levy DE, Asselin B, et al.: Results of the Dana-Farber Cancer Institute ALL Consortium Protocol 95-01 for children with acute lymphoblastic leukemia. Blood 109 (3): 896-904, 2007. [PUBMED Abstract]
- Matloub Y, Lindemulder S, Gaynon PS, et al.: Intrathecal triple therapy decreases central nervous system relapse but fails to improve event-free survival when compared with intrathecal methotrexate: results of the Children's Cancer Group (CCG) 1952 study for standard-risk acute lymphoblastic leukemia, reported by the Children's Oncology Group. Blood 108 (4): 1165-73, 2006. [PUBMED Abstract]
- Kadan-Lottick NS, Brouwers P, Breiger D, et al.: Comparison of neurocognitive functioning in children previously randomly assigned to intrathecal methotrexate compared with triple intrathecal therapy for the treatment of childhood acute lymphoblastic leukemia. J Clin Oncol 27 (35): 5986-92, 2009. [PUBMED Abstract]
- Schrappe M, Reiter A, Ludwig WD, et al.: Improved outcome in childhood acute lymphoblastic leukemia despite reduced use of anthracyclines and cranial radiotherapy: results of trial ALL-BFM 90. German-Austrian-Swiss ALL-BFM Study Group. Blood 95 (11): 3310-22, 2000. [PUBMED Abstract]
- Sirvent N, Suciu S, Rialland X, et al.: Prognostic significance of the initial cerebro-spinal fluid (CSF) involvement of children with acute lymphoblastic leukaemia (ALL) treated without cranial irradiation: results of European Organization for Research and Treatment of Cancer (EORTC) Children Leukemia Group study 58881. Eur J Cancer 47 (2): 239-47, 2011. [PUBMED Abstract]
- Moore IM, Espy KA, Kaufmann P, et al.: Cognitive consequences and central nervous system injury following treatment for childhood leukemia. Semin Oncol Nurs 16 (4): 279-90; discussion 291-9, 2000. [PUBMED Abstract]
- Goshen Y, Stark B, Kornreich L, et al.: High incidence of meningioma in cranial irradiated survivors of childhood acute lymphoblastic leukemia. Pediatr Blood Cancer 49 (3): 294-7, 2007. [PUBMED Abstract]
- Hijiya N, Hudson MM, Lensing S, et al.: Cumulative incidence of secondary neoplasms as a first event after childhood acute lymphoblastic leukemia. JAMA 297 (11): 1207-15, 2007. [PUBMED Abstract]
- Mahoney DH Jr, Shuster JJ, Nitschke R, et al.: Acute neurotoxicity in children with B-precursor acute lymphoid leukemia: an association with intermediate-dose intravenous methotrexate and intrathecal triple therapy--a Pediatric Oncology Group study. J Clin Oncol 16 (5): 1712-22, 1998. [PUBMED Abstract]
- Relling MV, Pui CH, Sandlund JT, et al.: Adverse effect of anticonvulsants on efficacy of chemotherapy for acute lymphoblastic leukaemia. Lancet 356 (9226): 285-90, 2000. [PUBMED Abstract]
- Waber DP, Turek J, Catania L, et al.: Neuropsychological outcomes from a randomized trial of triple intrathecal chemotherapy compared with 18 Gy cranial radiation as CNS treatment in acute lymphoblastic leukemia: findings from Dana-Farber Cancer Institute ALL Consortium Protocol 95-01. J Clin Oncol 25 (31): 4914-21, 2007. [PUBMED Abstract]
- Jansen NC, Kingma A, Schuitema A, et al.: Neuropsychological outcome in chemotherapy-only-treated children with acute lymphoblastic leukemia. J Clin Oncol 26 (18): 3025-30, 2008. [PUBMED Abstract]
- Espy KA, Moore IM, Kaufmann PM, et al.: Chemotherapeutic CNS prophylaxis and neuropsychologic change in children with acute lymphoblastic leukemia: a prospective study. J Pediatr Psychol 26 (1): 1-9, 2001 Jan-Feb. [PUBMED Abstract]
- Copeland DR, Moore BD 3rd, Francis DJ, et al.: Neuropsychologic effects of chemotherapy on children with cancer: a longitudinal study. J Clin Oncol 14 (10): 2826-35, 1996. [PUBMED Abstract]
- von der Weid N, Mosimann I, Hirt A, et al.: Intellectual outcome in children and adolescents with acute lymphoblastic leukaemia treated with chemotherapy alone: age- and sex-related differences. Eur J Cancer 39 (3): 359-65, 2003. [PUBMED Abstract]
- Waber DP, Carpentieri SC, Klar N, et al.: Cognitive sequelae in children treated for acute lymphoblastic leukemia with dexamethasone or prednisone. J Pediatr Hematol Oncol 22 (3): 206-13, 2000 May-Jun. [PUBMED Abstract]
- Kadan-Lottick NS, Brouwers P, Breiger D, et al.: A comparison of neurocognitive functioning in children previously randomized to dexamethasone or prednisone in the treatment of childhood acute lymphoblastic leukemia. Blood 114 (9): 1746-52, 2009. [PUBMED Abstract]
- Stubberfield TG, Byrne GC, Jones TW: Growth and growth hormone secretion after treatment for acute lymphoblastic leukemia in childhood. 18-Gy versus 24-Gy cranial irradiation. J Pediatr Hematol Oncol 17 (2): 167-71, 1995. [PUBMED Abstract]
- Rowland JH, Glidewell OJ, Sibley RF, et al.: Effects of different forms of central nervous system prophylaxis on neuropsychologic function in childhood leukemia. J Clin Oncol 2 (12): 1327-35, 1984. [PUBMED Abstract]
- Halberg FE, Kramer JH, Moore IM, et al.: Prophylactic cranial irradiation dose effects on late cognitive function in children treated for acute lymphoblastic leukemia. Int J Radiat Oncol Biol Phys 22 (1): 13-6, 1992. [PUBMED Abstract]
- Hill JM, Kornblith AB, Jones D, et al.: A comparative study of the long term psychosocial functioning of childhood acute lymphoblastic leukemia survivors treated by intrathecal methotrexate with or without cranial radiation. Cancer 82 (1): 208-18, 1998. [PUBMED Abstract]
- Pui CH, Cheng C, Leung W, et al.: Extended follow-up of long-term survivors of childhood acute lymphoblastic leukemia. N Engl J Med 349 (7): 640-9, 2003. [PUBMED Abstract]
- Jankovic M, Brouwers P, Valsecchi MG, et al.: Association of 1800 cGy cranial irradiation with intellectual function in children with acute lymphoblastic leukaemia. ISPACC. International Study Group on Psychosocial Aspects of Childhood Cancer. Lancet 344 (8917): 224-7, 1994. [PUBMED Abstract]
- Sklar C, Mertens A, Walter A, et al.: Final height after treatment for childhood acute lymphoblastic leukemia: comparison of no cranial irradiation with 1800 and 2400 centigrays of cranial irradiation. J Pediatr 123 (1): 59-64, 1993. [PUBMED Abstract]
- Christie D, Leiper AD, Chessells JM, et al.: Intellectual performance after presymptomatic cranial radiotherapy for leukaemia: effects of age and sex. Arch Dis Child 73 (2): 136-40, 1995. [PUBMED Abstract]
- Waber DP, Tarbell NJ, Kahn CM, et al.: The relationship of sex and treatment modality to neuropsychologic outcome in childhood acute lymphoblastic leukemia. J Clin Oncol 10 (5): 810-7, 1992. [PUBMED Abstract]
- Waber DP, Shapiro BL, Carpentieri SC, et al.: Excellent therapeutic efficacy and minimal late neurotoxicity in children treated with 18 grays of cranial radiation therapy for high-risk acute lymphoblastic leukemia: a 7-year follow-up study of the Dana-Farber Cancer Institute Consortium Protocol 87-01. Cancer 92 (1): 15-22, 2001. [PUBMED Abstract]
- Waber DP, Silverman LB, Catania L, et al.: Outcomes of a randomized trial of hyperfractionated cranial radiation therapy for treatment of high-risk acute lymphoblastic leukemia: therapeutic efficacy and neurotoxicity. J Clin Oncol 22 (13): 2701-7, 2004. [PUBMED Abstract]
- Löning L, Zimmermann M, Reiter A, et al.: Secondary neoplasms subsequent to Berlin-Frankfurt-Münster therapy of acute lymphoblastic leukemia in childhood: significantly lower risk without cranial radiotherapy. Blood 95 (9): 2770-5, 2000. [PUBMED Abstract]
- Bhatia S, Sather HN, Pabustan OB, et al.: Low incidence of second neoplasms among children diagnosed with acute lymphoblastic leukemia after 1983. Blood 99 (12): 4257-64, 2002. [PUBMED Abstract]
- Filley CM, Kleinschmidt-DeMasters BK: Toxic leukoencephalopathy. N Engl J Med 345 (6): 425-32, 2001. [PUBMED Abstract]