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

Long-term neurocognitive outcomes in young adult survivors of childhood acute lymphoblastic leukemia

Five-year survival rates of childhood acute lymphoblastic leukemia (ALL) exceed 80% due to central nervous system-directed treatment including cranial radiation (CRT) and chemotherapy. However, these treatments are associated with neurocognitive compromise, the extent of which is correlated with higher dose and younger age at treatment. The aims of this study were to explore long-term neurocognitive outcomes in adult survivors of childhood ALL, and to identify measures sensitive to neurotoxicity in long-term survivors. We examined 24 adults who received 18 Gy CRT and chemotherapy for treatment of ALL between ages 2 and 15 years (median, 5.5). Time since diagnosis ranged from 6 to 26 years (median, 16.6). Younger age at diagnosis and longer time since diagnosis were associated with lower scores on a computerized battery that requires speed and accuracy across a number of domains (MicroCog), and other standardized neurocognitive tests. When compared with population norms, MicroCog indices were below average in survivors diagnosed with ALL before age 5, but only the reasoning/calculation index was below average in survivors diagnosed with ALL after age 5. In contrast, intelligence quotient (IQ) scores were average. In addition to confirming earlier studies showing that younger children are more vulnerable to treatment-related neurotoxicity, here we show that deficits exist many years post treatment even with a relatively lower dose of CRT, and that these deficits are especially evident on tasks involving rapid processing of information.

Disruption of learning processes by chemotherapeutic agents in childhood survivors of acute lymphoblastic leukemia and preclinical models

OBJECTIVE

With the survival rate of acute lymphoblastic leukemia (ALL) surpassing 90 percent within this decade, new research is emerging in the field of late effects. A review of the research investigating the relationship of treatment regimens for ALL to specific late effect deficits, underlying mechanisms, and possible remediation is warranted to support continued studies.

METHODS

The clinical literature was briefly surveyed to describe the occurrence and topography of late effects, specifically neurocognitive deficits. Additionally, the preclinical literature was reviewed to uncover potential underlying mechanisms of these deficits. The advantages of using rodent models to answer these questions are outlined, as is an assessment of the limited number of rodent models of childhood cancer treatment.

RESULTS

The literature supports that childhood survivors of ALL exhibit academic difficulties and are more likely to be placed in a special education program. Behavioral evidence has highlighted impairments in the areas of attention, working memory, and processing speed, leading to a decrease in full scale IQ. Neurophysiological and preclinical evidence for these deficits has implicated white matter abnormalities and acquired brain damage resulting from specific chemotherapeutic agents commonly used during treatment.

CONCLUSIONS

The exact role of chemotherapeutic agents in learning deficits remains mostly unknown. Recommendations for an improved rodent model of learning deficits in childhood cancer survivors are proposed, along with suggestions for future directions in this area of research, in hopes that forthcoming treatment regimens will reduce or eliminate these types of impairments.

Randomized trial to compare LSA2L2-type maintenance therapy to daily 6-mercaptopurine and weekly methotrexate with vincristine and dexamethasone pulse for children with acute lymphoblastic leukemia

BACKGROUND

A total of 201 pediatric cases of acute lymphoblastic leukemia were treated with the ALL-96 protocol by the Kyushu-Yamaguchi Children's Cancer Study Group.

PROCEDURE

Risk stratification was based on white cell counts, immunophenotype, the presence of central nervous system disease at diagnosis, organomegaly, and early treatment response (day 14 bone marrow status). All of the patients were classified into standard-risk (SR) or high-risk (HR) groups and were randomly assigned to receive maintenance therapy with either LSA2L2-type or 6-mercaptopurine (6-MP)/methotrexate (MTX) with vincristine (VCR) and dexamethasone (DEX) pulse in both risk groups.

RESULTS

The 7-year event-free survival (EFS) and overall survival (OS) rates in the entire study population were 72.1% (95% CI: 68.0-76.2%) and 84.8% (95% CI: 79.7-89.9%), respectively, and the EFS of the SR patients (85.3% [95% CI: 78.2-92.4%]) was significantly better than HR patients (62.4% [95% CI: 52.2-72.6%]) (P = 0.0007).

CONCLUSIONS

There were no differences in the EFS between the different maintenance therapies in each risk group; however, grade IV liver toxicity occurred more often in the patients receiving 6-MP/MTX with VCR and DEX therapy than in patients receiving LSA2L2.

Neurocognitive functioning in adult survivors of childhood non-central nervous system cancers

BACKGROUND We sought to measure self-reported neurocognitive functioning among survivors of non-central nervous system (CNS) childhood cancers, overall and compared with a sibling cohort, and to identify factors associated with worse functioning. METHODS In a retrospective cohort study, 5937 adult survivors of non-CNS cancers and 382 siblings completed a validated neuropsychological instrument with subscales in task efficiency, emotional regulation, organization, and memory. Scores were converted to T scores; scores in the worst 10% of siblings' scores (ie, T score > or =63) were defined as impaired. Non-CNS cancer survivors and siblings were compared with multivariable linear regression and log-binomial regression. Among survivors, log-binomial models assessed the association of patient and treatment factors with neurocognitive dysfunction. All statistical tests were two-sided. RESULTS Non-CNS cancer survivors had similar or slightly worse (<0.5 standard deviation) mean test scores for all four subscales than siblings. However, frequencies of impaired survivors were approximately 50% higher than siblings in task efficiency (13.0% of survivors vs 7.3% of siblings), memory (12.5% vs 7.6%), and emotional regulation (21.2% vs 14.4%). Impaired task efficiency was most often identified in patients with acute lymphoblastic leukemia who received cranial radiation therapy (18.1% with impairment), myeloid leukemia who received cranial radiation therapy (21.2%), and non-Hodgkin lymphoma (13.9%). In adjusted analysis, diagnosis age of younger than 6 years, female sex, cranial radiation therapy, and hearing impairment were associated with impairment. CONCLUSION A statistically and clinically significantly higher percentage of self-reported neurocognitive impairment was found among survivors of non-CNS cancers than among siblings.

Radiation dose-volume effects in the brain

We have reviewed the published data regarding radiotherapy (RT)-induced brain injury. Radiation necrosis appears a median of 1-2 years after RT; however, cognitive decline develops over many years. The incidence and severity is dose and volume dependent and can also be increased by chemotherapy, age, diabetes, and spatial factors. For fractionated RT with a fraction size of <2.5 Gy, an incidence of radiation necrosis of 5% and 10% is predicted to occur at a biologically effective dose of 120 Gy (range, 100-140) and 150 Gy (range, 140-170), respectively. For twice-daily fractionation, a steep increase in toxicity appears to occur when the biologically effective dose is >80 Gy. For large fraction sizes (>or=2.5 Gy), the incidence and severity of toxicity is unpredictable. For single fraction radiosurgery, a clear correlation has been demonstrated between the target size and the risk of adverse events. Substantial variation among different centers' reported outcomes have prevented us from making toxicity-risk predictions. Cognitive dysfunction in children is largely seen for whole brain doses of >or=18 Gy. No substantial evidence has shown that RT induces irreversible cognitive decline in adults within 4 years of RT.

Neurotoxicity of radiation therapy

Direct or incidental exposure of the nervous system to therapeutic irradiation carries the risk of symptomatic neurologic injury. Central nervous system toxicity from radiation includes focal cerebral necrosis, neurocognitive deficits, and less commonly cerebrovascular disease, myelopathy, or the occurrence of a radiation-induced neoplasm. Brachial or lumbosacral plexopathy are the most common syndromes of radiation toxicity affecting the peripheral nervous system. This article focuses on the clinical features, diagnosis, and management options for patients with radiation neurotoxicity.

Risk-adapted treatment of pediatric acute lymphoblastic leukemia

Optimal use of antileukemic agents and stringent application of risk-directed therapy in clinical trials have resulted in steady improvement in the outcome of children with acute lymphoblastic leukemia, with current cure rates exceeding 80% in developed countries. The intensity of treatment varies substantially among subsets of patients, as therapy is designed to reduce acute and long-term toxicity in low-risk groups while improving outcomes in poor risk groups by treatment intensification. Recent advances in genome-wide screening techniques, pharmacogenomic studies, and development of molecular therapeutics are ushering in an era of more refined personalized therapy.

Long-term results of Dana-Farber Cancer Institute ALL Consortium protocols for children with newly diagnosed acute lymphoblastic leukemia (1985-2000)

The Dana-Farber Cancer Institute (DFCI) ALL Consortium has been conducting multi-institutional clinical trials in childhood ALL since 1981. The treatment backbone has included 20–30 consecutive weeks of asparaginase during intensification and frequent vincristine/corticosteroid pulses during the continuation phase. Between 1985–2000, 1457 children aged 0–18 years were treated on four consecutive protocols: 85-01 (1985–7), 87-01 (1987–91), 91-01 (1991–5) and 95-01 (1996–2000). The 10-year event-free survival (EFS) ± standard error by protocol was 77.9 ± 2.8% (85-01), 74.2± 2.3 (87-01), 80.8 ± 2.1% (91-01) and 80.5 ± 1.8% (95-01). Approximately 82% of patients treated in the 1980s and 88% treated in the 1990s were long-term survivors. Both EFS and overall survival (OS) rates were significantly higher for patients treated in the 1990s compared with the 1980s (p=0.05 and 0.01, respectively). On the two protocols conducted in the 1990s, EFS was 79–85% for T-ALL patients and 75–78% for adolescents (age 10–18 years). Results of randomized studies revealed that dexrazoxane prevented acute cardiac injury without adversely impacting EFS or OS in high-risk patients and frequently-dosed intrathecal chemotherapy was an effective substitute for cranial radiation in standard-risk patients. Current studies continue to focus on improving efficacy while minimizing acute and late toxicities.

Oxidative stress and executive function in children receiving chemotherapy for acute lymphoblastic leukemia

BACKGROUND

Neurocognitive sequelae following treatment for pediatric acute lymphoblastic leukemia (ALL) has been reported in a significant proportion of survivors, including those treated only with chemotherapy. Early identification of children "at risk" for neurocognitive problems is not yet reliable. Biomarkers of oxidative stress (e.g., oxidated phosphatidylcholine) in cerebral spinal fluid (CSF) have been correlated with intensity of methotrexate (MTX) treatment, suggesting an association with acute central nervous system toxicity.

PROCEDURE

This study examined the association between oxidized CSF phospholipids and executive functions throughout chemotherapy. Measures of oxidative stress and executive functions were examined in 88 children newly diagnosed with ALL. The children were followed over 3 years with neurocognitive testing and parent ratings of executive functions.

RESULTS

Results demonstrated an association between increased oxidative stress following induction and consolidation and decreased executive function 2 years later. Younger age at diagnosis was associated with both an increase in oxidative stress and in executive dysfunction; younger age was associated with poorer ability to organize materials in one's environment (r(48) = 0.28, P < 0.05) and with greater oxidated phosphatidylcholine in CSF at the end of chemotherapy (r(48) = -0.27, P < 0.05). As such, younger age appears to be the most prominent moderator of neurocognitive decline.

CONCLUSIONS

These results link functional changes to CSF biomarkers and underscore the importance of monitoring cognitive development in young children treated for ALL. Children with less advanced central nervous system development may be particularly vulnerable to the effects of chemotherapy.

Investigating verbal and visual auditory learning after conformal radiation therapy for childhood ependymoma

PURPOSE

The primary objective of this study was to determine whether children with localized ependymoma experience a decline in verbal or visual-auditory learning after conformal radiation therapy (CRT). The secondary objective was to investigate the impact of age and select clinical factors on learning before and after treatment.

METHODS AND MATERIALS

Learning in a sample of 71 patients with localized ependymoma was assessed with the California Verbal Learning Test (CVLT-C) and the Visual-Auditory Learning Test (VAL). Learning measures were administered before CRT, at 6 months, and then yearly for a total of 5 years.

RESULTS

There was no significant decline on measures of verbal or visual-auditory learning after CRT; however, younger age, more surgeries, and cerebrospinal fluid shunting did predict lower scores at baseline. There were significant longitudinal effects (improved learning scores after treatment) among older children on the CVLT-C and children that did not receive pre-CRT chemotherapy on the VAL.

CONCLUSION

There was no evidence of global decline in learning after CRT in children with localized ependymoma. Several important implications from the findings include the following: (1) identification of and differentiation among variables with transient vs. long-term effects on learning, (2) demonstration that children treated with chemotherapy before CRT had greater risk of adverse visual-auditory learning performance, and (3) establishment of baseline and serial assessment as critical in ascertaining necessary sensitivity and specificity for the detection of modest effects.

Progressive neurocognitive impairment in young adult survivors of childhood acute lymphoblastic leukemia

BACKGROUND

Despite the extensive literature on neuropsychological sequelae after treatment of childhood acute lymphoblastic leukemia (ALL), the very-long-term neurocognitive outcome of the survivors is poorly studied. We assessed neuropsychological functioning in a population-based cohort of young adult childhood ALL survivors.

PROCEDURE

Neuropsychological testing was performed on 64 survivors an average of 20 years after the diagnosis. The test battery included verbal intelligence quotient (VIQ) and performance intelligence quotient (PIQ), memory function, orientation and attention as well as motor performance. Cranial irradiation had been administered to 44 survivors as part of ALL treatment, whereas 20 survivors had been treated solely with chemotherapy. A control group consisted of 45 healthy young adults. Earlier neuropsychological test results of 45 of the survivors were available for comparison.

RESULTS

The ALL survivors attained significantly lower test scores than the controls in all the neuropsychological function areas. The mean VIQ test scores were 91, 100, and 109 (P < 0.001), and the mean PIQ test scores 100, 111, and 118 (P < 0.001) for the irradiated survivors, non-irradiated survivors and controls, respectively. Memory and motor functions were impaired among the irradiated survivor group compared with the controls. A significant decline in PIQ and VIQ test scores was observed in the irradiated survivor group during the follow-up period, but only in VIQ in the non-irradiated group.

CONCLUSIONS

Survivors of childhood ALL suffer from long-lasting progressive neuropsychological impairment, especially when treatment includes cranial irradiation.

Treating childhood acute lymphoblastic leukemia without cranial irradiation

BACKGROUND

Prophylactic cranial irradiation has been a standard treatment in children with acute lymphoblastic leukemia (ALL) who are at high risk for central nervous system (CNS) relapse.

METHODS

We conducted a clinical trial to test whether prophylactic cranial irradiation could be omitted from treatment in all children with newly diagnosed ALL. A total of 498 patients who could be evaluated were enrolled. Treatment intensity was based on presenting features and the level of minimal residual disease after remission-induction treatment. The duration of continuous complete remission in the 71 patients who previously would have received prophylactic cranial irradiation was compared with that of 56 historical controls who received it.

RESULTS

The 5-year event-free and overall survival probabilities for all 498 patients were 85.6% (95% confidence interval [CI], 79.9 to 91.3) and 93.5% (95% CI, 89.8 to 97.2), respectively. The 5-year cumulative risk of isolated CNS relapse was 2.7% (95% CI, 1.1 to 4.3), and that of any CNS relapse (including isolated relapse and combined relapse) was 3.9% (95% CI, 1.9 to 5.9). The 71 patients had significantly longer continuous complete remission than the 56 historical controls (P=0.04). All 11 patients with isolated CNS relapse remained in second remission for 0.4 to 5.5 years. CNS leukemia (CNS-3 status) or a traumatic lumbar puncture with blast cells at diagnosis and a high level of minimal residual disease (> or = 1%) after 6 weeks of remission induction were significantly associated with poorer event-free survival. Risk factors for CNS relapse included the genetic abnormality t(1;19)(TCF3-PBX1), any CNS involvement at diagnosis, and T-cell immunophenotype. Common adverse effects included allergic reactions to asparaginase, osteonecrosis, thrombosis, and disseminated fungal infection.

CONCLUSIONS

With effective risk-adjusted chemotherapy, prophylactic cranial irradiation can be safely omitted from the treatment of childhood ALL. (ClinicalTrials.gov number, NCT00137111.)

Neurodevelopmental sequelae of pediatric acute lymphoblastic leukemia and its treatment

This review will describe the neurocognitive outcomes associated with pediatric acute lymphoblastic leukemia (ALL) and its treatment. The literature is reviewed with the aim of addressing methodological issues, treatment factors, risks and moderators, special populations, relationship to neuroimaging findings, and directions for future research. It is concluded that neurocognitive outcomes for the majority of children with standard-risk ALL treated according to current chemotherapy protocols is relatively good, but subgroups of children are more significantly compromised. As medical treatments advance and survival rates continue to improve, neurocognitive outcomes and other quality of life indicators will become increasingly important. Preventing or ameliorating treatment-related neuropsychological sequelae represents the next major challenge in pediatric ALL.

Pharmacogenetics of the neurodevelopmental impact of anticancer chemotherapy

Pharmacogenetics holds the promise of minimizing adverse neurodevelopmental outcomes of cancer patients by identifying patients at risk, enabling the individualization of treatment and the planning of close follow-up and early remediation. This review focuses first on methotrexate, a drug often implicated in neurotoxicity, especially when used in combination with brain irradiation. The second focus is on glucocorticoids that have been found to be linked to adverse developmental effects in relation with the psychosocial environment. For both examples, we review how polymorphisms of genes encoding enzymes involved in specific mechanisms of action could moderate adverse neurodevelopmental consequences, eventually through common final pathways such as oxidative stress. We discuss a multiple hit model and possible strategies required to rise to the challenge of this integrative research.

Intrathecal chemotherapy for hematologic malignancies: drugs and toxicities

Intrathecal (IT) chemotherapy is an important component of the prophylaxis or treatment of hematologic malignancies in the central nervous system (CNS), especially in patients with acute lymphoblastic leukemia and aggressive lymphomas. Different regimens of IT chemotherapies have been formulated, often in conjunction with systemic high-dose chemotherapy leading to penetration of the drugs into the cerebrospinal fluid (CSF). The three commonest IT drugs are methotrexate, cytosine arabinoside (Ara-C), and corticosteroids. The CSF half-lives of methotrexate and Ara-C are much prolonged, a factor to be considered if these drugs are also administered systemically in high doses. Neurotoxicities attributed to IT chemotherapy have been reported, including spinal cord lesions, seizures, and encephalopathy. Spinal cord lesions, manifesting as tetraplegia, paraplegia, and cauda equina syndrome, are the commonest neurotoxicity. It is mostly related to combined IT methotrexate and Ara-C, or Ara-C as the sole IT agent when given at high doses or as a slow-release preparation. Cord lesions rarely recover and patients are left with motor deficits, bowel and urinary disabilities. Seizures and encephalopathy are reported in relatively fewer patients, with variable manifestations and prognosis. Knowledge of the pharmacokinetics, dosing schedules and potential toxicities of IT chemotherapeutic drugs is important in the design of CNS prophylaxis and treatment in hematologic malignancies.

The pediatric cancer hospitalization experience: reality co-constructed

Although pediatric cancer treatment has been reviewed by several authors, the lived experiences of children undergoing this process have seldom been discussed in the literature. The data for this article were obtained from a larger qualitative study that provided a collective view of the pediatric cancer experience at San Jorge Children's Hospital in Puerto Rico. In this article, findings that are directly related to the hospitalization process of these young patients are described, including the hospital as a safe haven, dealing with pain, taking control, and thriving in adversity. These findings provide a rationale for the development of a biopsychosocial model of health that emphasizes reciprocal interactions among the biological, psychological, social, cultural, and spiritual dimensions that influence health.