Slight cognitive impairment and magnetic resonance imaging abnormalities but normal school levels in children treated for acute lymphoblastic leukemia with chemotherapy only

Effects of chemotherapeutic agents 5-fluorouracil and methotrexate alone and combined in a mouse model of learning and memory

RATIONALE

The concern that adjuvant cancer chemotherapy agents cause cognitive impairment in a significant number of patients has been expressed by patients and healthcare providers, but clinical studies have yielded conflicting results to date.

OBJECTIVE

We directly tested two commonly used chemotherapeutic agents in a mouse model of learning and memory.

MATERIALS AND METHODS

In the present study, mice were conditioned to respond for a liquid reinforcer (Ensure solution) in the presence of an audible tone on day 1 as a measure of acquisition and were then required to perform the same response on day 2 as a measure of retrieval and retention. Methotrexate and 5-fluorouracil were administered prior to the day 1 session.

RESULTS

Methotrexate (1.0-32 mg/kg) alone failed to alter mean latency acquisition, retrieval, or reinforced response rates. Similar to scopolamine, a known amnesic in this assay, 5-fluorouracil (3-75 mg/kg) failed to alter response rates or acquisition latency on day 1 but significantly altered latency to retrieve a previously learned response on day 2. In combination, 3.2 mg/kg methotrexate plus 75 mg/kg 5-fluorouracil significantly increased day 1 and day 2 acquisition and retrieval latencies without altering response rates or motivation to respond as measured by progressive ratio responding.

CONCLUSION

Taken together, these data demonstrate that 5-fluorouracil causes increased latencies for retrieval of previously learned behavioral responses and that combination of chemotherapeutic agents may produce greater delays than either agent alone, including when neither agent alone does so.

A meta-analysis of the neuropsychological sequelae of chemotherapy-only treatment for pediatric acute lymphoblastic leukemia

BACKGROUND

Mixed findings on the neuropsychological sequelae of chemotherapy-only treatment for pediatric acute lymphoblastic leukemia (ALL), without radiation, indicate the need for a comprehensive meta-analytic review. The purpose of the current study was to conduct a meta-analysis assessing neuropsychological and academic functioning differences between children with ALL treated solely with chemotherapy and comparison groups.

PROCEDURE

Thirteen articles met inclusion criteria for the meta-analysis and were analyzed using a random effects model, weighted least squares methods.

RESULTS

Mean effect sizes were significantly different from zero for multiple domains of intelligence and academic achievement; processing speed; verbal memory; and some aspects of executive functioning and fine motor skills, indicating worse functioning in ALL survivors. Effect sizes for visual-motor skills and visual memory were not significantly different from zero.

CONCLUSIONS

Results support the presence of neuropsychological and academic sequelae for ALL survivors treated solely with chemotherapy and highlight the need for ongoing follow-up of children with ALL using a standardized neuropsychological test battery and research methodology.

The usefulness of growth hormone treatment for psychological status in young adult survivors of childhood leukaemia: an open-label study

BACKGROUND

To reduce the risk of brain damage children with acute lymphoblastic leukaemia (ALL) are nowadays mainly treated with intrathecal chemotherapy (ITC) instead of central nervous system (CNS) radiation therapy (CRT) to prevent CNS relapse. However, chemotherapy may also lead to cognitive deficits. As growth hormone deficiency (GHD) or impaired growth hormone secretion are frequently found in ALL patients treated with cranial radiation therapy and/or chemotherapy, we hypothesized that GH therapy may reduce cognitive deficits in these patients.

METHODS

Twenty young adult survivors of childhood ALL with reduced bone mineral density (<-1 SD) and/or low IGF-I SD-scores (<-1 SD) were included in the study. A final group of 13 patients (9 males and 4 females), mean age 23.7 +/- 2.9 years (range 20 - 29.7) completed a 2-year treatment with GH.IQ and neuropsychological performance were assessed at pre-treatment (T1) and after one (T2) and two (T3) years. ANOVA was performed with assessment at T1, T2 and T3 as repeated measurements factor. Relations between test score changes and changes of IGF-I levels were determined by calculating the Pearson correlation coefficient.

RESULTS

Scores on the cognitive tests were in the normal range. Verbal short- and long-term memory performance decreased between T1 and T2, and increased between T2 and T3. Performance at T3 was not significantly different from that at T1. Performance for sustained attention improved from T1 to T2 and from T1 to T3. Visual-spatial memory was improved after one year of GH treatment. A significant positive correlation was found for Delta IGF-I (T2-T1) with difference scores of visual-spatial memory (T2-T1 and T3-T1), indicating that IGF-I increase after one year of GH treatment is associated with increase in cognitive-perceptual performance at month 12 and 24.

CONCLUSION

Since the level of intellectual functioning of our patient cohort was in the normal range the present finding that GH treatment has negative effects on verbal memory and positive on attention and visual-spatial memory warrants similar studies in other groups of ALL survivors. Also, a lower dose of GH should be determined inducing as much IGF as needed to improve verbal as well as visual cognitive functions. The present findings indicate that more knowledge is needed before GH treatment may be recommended to enhance cognitive functions in ALL survivors.

Neuropsychological Outcome in Chemotherapy-Only–Treated Children With Acute Lymphoblastic Leukemia

Purpose

To evaluate neuropsychological functioning over time in children treated for acute lymphoblastic leukemia (ALL) with chemotherapy only.

Patients and Methods

Forty-nine consecutive patients (median age at first assessment, 6.8 years; range, 4.0 to 11.8 years) treated with intrathecal and systemic chemotherapy were included in a nationwide, prospective-longitudinal, sibling-controlled study. Patients and siblings completed three extensive neuropsychological assessments: at diagnosis, 3 to 6 months after completion of (2-year) treatment and 4.5 years after diagnosis. Assessments included measures of learning, memory, attention, speed, executive functioning, visual-constructive functioning, and fine-motor functioning. Multilevel analyses were applied to evaluate patients' performances over time and to compare patients to 29 siblings (median age of siblings at first assessment, 8.2 years; range, 4.5 to 12.6 years) and to normative data.

Results

No major differences were found in neuropsychological performance between patients and siblings, with both groups performing mainly in the normal range. The patient group as a whole, however, scored significantly lower than the siblings on complex fine-motor functioning at the last evaluation. Large practice effects were found for both patients and siblings in four of 11 tasks. Patients who uttered physical complaints (ie, pain and/or tiredness) at the first pretreatment assessment scored significantly lower than siblings on attention and speed at the last two evaluations.

Conclusion

Despite intensive and potentially neurotoxic treatment, no evident negative, neuropsychological late effects were found 4.5 years after diagnosis, except for effects on complex fine-motor functioning. Both the large practice effects observed and the poorer performances on sustained attention for patients with physical complaints should be reckoned with in prospective, longitudinal neuropsychological research in children.

Reduced frontal white matter volume in long-term childhood leukemia survivors: a voxel-based morphometry study

BACKGROUND AND PURPOSE

To our knowledge, no published studies have examined whole-brain regional differences to identify more discrete volumetric changes in the brains of childhood leukemia survivors. We used voxel-based morphometry (VBM) to examine regional gray and white matter differences in a group of long-term survivors of acute lymphoblastic leukemia (ALL) compared with a group of healthy controls. Differences in regional white matter volume were expected, given previous reports of white matter changes during treatment for ALL and reduced brain white matter volumes in long-term survivors. Follow-up analyses examined the relationship of regional brain volumes to cognitive function.

MATERIALS AND METHODS

We compared 9 long-term survivors of ALL with 14 healthy controls. Survivors of ALL were treated with systemic and intrathecal chemotherapy only. T1-weighted axial 3D spoiled gradient high-resolution images collected on a 1.5T MR imaging scanner were used for the VBM analysis. Neuropsychological evaluations were conducted within 2 months of the MR imaging to assess cognitive function.

RESULTS

VBM analysis revealed 2 specific regions of reduced white matter in the right frontal lobes of survivors of ALL compared with healthy controls. Survivors of ALL had lower performances on tests of attention, visual-constructional skills, mental flexibility, and math achievement compared with healthy individuals. Decreased performance on neuropsychological measures was associated with decreased regional white matter volumes. No differences were found between the groups with respect to gray matter regions.

CONCLUSION

These findings are consistent with previous literature describing the long-term cognitive, academic, and imaging findings of survivors of ALL and suggest that right frontal white matter is particularly vulnerable to disruption following intensive chemotherapy for ALL. Future studies should focus on further clarifying the white matter changes observed.

Challenges after curative treatment for childhood cancer and long-term follow up of survivors

Childhood cancer survivors are at increased risk of serious morbidity, premature mortality, and diminished health status. Proactive and anticipatory risk-based health care of survivors and healthy lifestyles can reduce these risks. In this article, the authors first briefly discuss four common problems of survivors: neurocognitive dysfunction, cardiovascular disease, infertility and gonadal dysfunction, and psychosocial problems. Second, the authors discuss the concept of risk-based care, promote the use of recently developed evidence-based guidelines, describe current care in the United States, Canada, and the Netherlands, and articulate a model for shared survivor care that aims to optimize life long health of survivors and improve two-way communication between the cancer center and the primary care physician.

Scholastic Achievements of Childhood Leukemia Patients: A Nationwide, Register-Based Study

Purpose

Studies concerning the scholastic achievement of survivors of childhood leukemia have yielded controversial results. We studied the school marks of childhood leukemia survivors in a register-based study.

Patients and Methods

Three hundred seventy-one patients with a diagnosis of leukemia before the age of 16 years who were born between 1974 and 1986 and alive on their 16th birthday were identified from the Finnish Cancer Registry. Five matched controls were sought for each patient from the Population Register Center of Finland. Information on the ninth-grade school report was obtained from Statistics Finland. The overall mark average and the marks (scale 4 to 10) for mother tongue, foreign language, mathematics, and physical education were compared between the patients and controls.

Results

The ninth-grade school report was obtained by 97.6% of the patients and 98.5% of the controls. The patients whose treatment included cranial irradiation had a lower overall mark average (mean difference, −0.24; 95% CI, −0.33 to −0.15) and lower marks for all assessed school subjects compared with their controls. Of the patients treated with chemotherapy alone, only the females with leukemia diagnosed before 7 years of age had lower school marks than their controls. The biggest difference was observed in the marks for foreign language among the irradiated females diagnosed at a young age (mean difference, −1.0; 95% CI, −1.25 to −0.74).

Conclusion

Leukemia treatment that includes cranial irradiation impairs scholastic achievement. It is noteworthy that treatment of leukemia with chemotherapy alone impairs school performance only in females diagnosed before school age.

Quantitative morphologic evaluation of magnetic resonance imaging during and after treatment of childhood leukemia

INTRODUCTION

Medical advances over the last several decades, including CNS prophylaxis, have greatly increased survival in children with leukemia. As survival rates have increased, clinicians and scientists have been afforded the opportunity to further develop treatments to improve the quality of life of survivors by minimizing the long-term adverse effects. When evaluating the effect of antileukemia therapy on the developing brain, magnetic resonance (MR) imaging has been the preferred modality because it quantifies morphologic changes objectively and noninvasively.

METHOD AND RESULTS

Computer-aided detection of changes on neuroimages enables us to objectively differentiate leukoencephalopathy from normal maturation of the developing brain. Quantitative tissue segmentation algorithms and relaxometry measures have been used to determine the prevalence, extent, and intensity of white matter changes that occur during therapy. More recently, diffusion tensor imaging has been used to quantify microstructural changes in the integrity of the white matter fiber tracts. MR perfusion imaging can be used to noninvasively monitor vascular changes during therapy. Changes in quantitative MR measures have been associated, to some degree, with changes in neurocognitive function during and after treatment.

CONCLUSION

In this review, we present recent advances in quantitative evaluation of MR imaging and discuss how these methods hold the promise to further elucidate the pathophysiologic effects of treatment for childhood leukemia.

Neurologic toxicities of cancer therapies

Neurologic dysfunction is a well-recognized adverse effect of cancer therapeutics. The most common manifestations include peripheral neuropathy and encephalopathy. Often, symptoms resolve or improve upon removal of the offending agent; therefore, it is essential that clinicians recognize the symptoms and signs of injury. Occasionally, symptoms persist or develop after discontinuation of medication and may culminate in disability and diminished quality of life. As our understanding of neurotoxicity improves, medications with less potential for injury may be developed. In addition, potential antidotes to prevent or reverse injury may emerge. This review focuses on the clinical features, mechanisms, and possible therapeutics of the neurotoxicity of chemotherapy. In particular, oxaliplatin, thalidomide, methotrexate, ifosfamide, cytarabine, amifostine, acetyl-L-carnitine, methylene blue, cytokines, and neurotrophins are discussed.

Post-treatment intellectual functioning in children treated for acute lymphoblastic leukaemia (ALL) with chemotherapy-only: A prospective, sibling-controlled study

Intellectual functioning (verbal, performance and full-scale IQ) in 43 children treated for acute lymphoblastic leukaemia (ALL) with chemotherapy-only was evaluated in a nationwide, prospective, sibling-controlled study. Intellectual assessment was performed at diagnosis and repeated shortly after cessation of 2 years treatment, including intrathecal and systemic chemotherapy. Using hierarchical regression analysis, patients' and siblings' (n=27) scores were longitudinally analysed and compared to assess possible changes and differences over time. At both assessments, before and after treatment, the patients showed average scores on intelligence tests compared to population norms. Longitudinal analysis and cross-sectional comparisons revealed no significant differences between patients and controls. Young patients showed a small relative decline, albeit not significant, on performance-IQ compared to healthy siblings. Despite intensive and potentially neurotoxic treatment, no evident negative effects on intelligence were found. However, it cannot be precluded that younger patients are at risk for a small decline in PIQ.

Surviving childhood cancer: the impact on life

With modern therapies, most children diagnosed with cancer are expected to reach adulthood. Therefore, there are large and ever-increasing numbers of children and young adults in our population who are survivors of childhood cancer. Many of the therapies responsible for improved cancer survival rates can also damage normal cells and tissues. As more children survive cancer, the physical and emotional costs of enduring cancer therapy become increasingly important. Although most childhood cancer survivors are now expected to survive, they remain at risk for relapse, second malignant neoplasms, organ dysfunction, and a negative psychologic impact. Individual risk is quite variable and is dependent on multiple factors including the type and site of cancer, the therapy utilized, and the individual's constitution. The risks are likely to change as we learn more about the specific long-term effects of cancer therapy, develop more refined and targeted therapies, and develop and apply more effective preventative strategies or therapeutic interventions. Guidelines for long-term follow-up have been established and are available to help facilitate appropriate monitoring of and care for potential late effects.

Results of the Dana-Farber Cancer Institute ALL Consortium Protocol 95-01 for children with acute lymphoblastic leukemia

The Dana-Farber Cancer Institute (DFCI) Childhood ALL Consortium Protocol 95-01 was designed to minimize therapy-related morbidity for children with newly diagnosed ALL without compromising efficacy. Patients participated in randomized comparisons of (1) doxorubicin given with or without dexrazoxane, a cardioprotectant (high-risk patients), (2) intensive intrathecal chemotherapy and cranial radiation (standard-risk patients), and (3) Erwinia and Escherichia coli asparaginase (all patients). Between 1996 and 2000, 491 patients (aged 0-18 years) were enrolled (272 standard risk and 219 high risk). With a median of 5.7 years of follow-up, the estimated 5-year event-free survival (EFS) for all patients was 82%+/-2%. Dexrazoxane did not have a significant impact on the 5-year EFS of high-risk patients (P=.99), and there was no significant difference in outcome of standard-risk patients based on type of central nervous system (CNS) treatment (P=.26). Compared with E coli asparaginase, Erwinia asparaginase was associated with a lower incidence of toxicity (10% versus 24%), but also an inferior 5-year EFS (78%+/-4% versus 89%+/-3%, P=.01). We conclude that (1) dexrazoxane does not interfere with the antileukemic effect of doxorubicin, (2) intensive intrathecal chemotherapy is as effective as cranial radiation in preventing CNS relapse in standard-risk patients, and (3) once-weekly Erwinia is less toxic than E coli asparaginase, but also less efficacious.

Behavioral and educational limitations after chemotherapy for childhood acute lymphoblastic leukemia or Wilms tumor

BACKGROUND

The improved prognosis of childhood cancer makes monitoring of functional outcome important. The purpose of this study was to evaluate behavioral and educational functioning in survivors of childhood acute lymphoblastic leukemia (ALL) or a Wilms tumor. In this study, children with ALL received central nervous system directed chemotherapy without cranial irradiation.

METHODS

In a multicenter study, behavioral functioning and school performance was examined in 199 children age 4 to 18. Sixty-four children were at least 1 year from finishing treatment with chemotherapy for ALL (n = 28) or a Wilms tumor (n = 36). They were compared with siblings (n = 37) and with a control group of healthy schoolchildren (n = 98).

RESULTS

A moderately increased risk of behavioral and educational problems was found in children with ALL but not in children with Wilms tumor. School performance was poorer in children with ALL attending primary school compared with same-age peers; however, the rate of utilization of special education services was low. Teacher-rated behavior and mathematics performance was correlated with attention function in children with ALL. An excess of problem behavior and underperformance at school was found in the ALL high-risk group compared with the standard-risk group. No differences were found between siblings and controls.

CONCLUSION

Evidence is provided of subtle but significant behavioral and educational problems in survivors of childhood ALL, but no dysfunctions in survivors of a Wilms tumor. Careful follow-up of children with ALL treated with chemotherapy only is warranted.

Level of tau protein in children treated for acute lymphoblastic leukemia

Long-term neuropsychological complications such as attention and concentration disturbances, poor school performance, hyperexcitability, and even leukoencephalopathy have been described in children after chemotherapy for acute lymphoblastic leukemia. Elevation of the cerebrospinal fluid level of tau protein, associated with neuronal axons, is a neurodegenerative marker. The aim of the study was to assess the level of cerebrospinal fluid tau protein in children with acute lymphoblastic leukemia. The study included 26 patients with acute lymphoblastic leukemia and 19 patients with clinical symptoms of cerebrospinal meningitis (reference group). Tau protein levels were determined by enzyme-linked immunosorbent assay. Cerebrospinal fluid total protein level was not elevated in any of the samples. The examination was performed at diagnosis, after induction treatment, during consolidation, and after reinduction, i.e. before maintenance therapy. Neither age nor sex had an effect on tau protein levels in both groups. The mean tau protein value at diagnosis was 244.84 +/- 98.96 pg/mL in the study group (norm 300 pg/mL) and produced no correlation with initial leukocytosis, lactate dehydrogenase activity, or organomegaly at this point. Dynamic analysis revealed a statistically significant increase in tau protein after induction treatment (431.25 +/- 232.50) as compared with its level at diagnosis (244.84 +/- 98.96, P < 0.008) and later during treatment. The levels of tau protein at various points of treatment did not differ statistically significantly between the groups, except for the values obtained after termination of remission induction. The observed metabolic changes in tau protein, which is a known marker of neuronal damage, indicate that some patients are at a greater risk of central nervous system disorders. This finding requires further studies, also in reference to other central nervous system proteins, and confirms the necessity of long-term follow-up of leukemia patients.

Computer-aided detection of therapy-induced leukoencephalopathy in pediatric acute lymphoblastic leukemia patients treated with intravenous high-dose methotrexate

The purpose of this study was to use objective quantitative magnetic resonance imaging (MRI) methods to develop a computer-aided detection (CAD) tool to differentiate white matter (WM) hyperintensities into either leukoencephalopathy (LE) induced by chemotherapy or normal maturational processes in children treated for acute lymphoblastic leukemia without irradiation. A combined MRI set consisting of T1-weighted, T2-weighted, proton-density-weighted and fluid-attenuated inversion recovery images and WM, gray matter and cerebrospinal fluid proportional volume maps from a spatially normalized atlas were analyzed with a neural network segmentation based on a Kohonen self-organizing map (SOM). Segmented maps were manually classified to identify the most hyperintense WM region and the normal-appearing genu region. Signal intensity differences normalized to the genu within each examination were generated for four time points in 228 children. A second Kohonen SOM was trained on the first examination data and divided the WM into normal-appearing or LE groups. Reviewing labels from the CAD tool revealed a consistency measure of 89.8% (167 of 186) within patients. The overall agreement between the CAD tool and the consensus reading of two trained observers was 84.1% (535 of 636), with 84.2% (170 of 202) agreement in the training set and 84.1% (365 of 434) agreement in the testing set. These results suggest that subtle therapy-induced LE can be objectively and reproducibly detected in children treated for cancer using this CAD approach based on relative differences in quantitative signal intensity measures normalized within each examination.

Delayed neurotoxicity associated with therapy for children with acute lymphoblastic leukemia

Most children diagnosed today with acute lymphoblastic leukemia (ALL) will be cured. However, treatment entails risk of neurotoxicity, causing deficits in neurocognitive function that can persist in the years after treatment is completed. Many of the components of leukemia therapy can contribute to adverse neurologic sequelae, including craniospinal irradiation, nucleoside analogs, corticosteroids, and antifolates. In this review, we describe the characteristic radiographic findings and neurocognitive deficits seen among survivors of childhood ALL. We summarize what is known about the pathophysiology of delayed treatment-related neurotoxicity, with a focus on the toxicity resulting from pharmacologic disruption of folate physiology within the central nervous system. Finally, we suggest testable strategies to ameliorate the symptoms of treatment-related neurotoxicity or decrease its incidence.

Visuomotor control in survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only

Treatment for childhood acute lymphoblastic leukemia (ALL), which includes CNS prophylaxis, is associated with central and peripheral neurotoxicity. The purpose of the present study was to analyze the effects of chemotherapy on various levels of visuomotor control in survivors of childhood ALL treated without cranial irradiation, and to identify risk factors for possible deficits. Visuomotor function was compared between children after treatment for ALL (n = 34), children after treatment for Wilms tumor, which consists of non-CNS directed chemotherapy (n = 38), and healthy controls (n = 151). Three tasks were administered: a simple visual reaction time task and two tasks measuring visuomotor control with one requiring a higher level of cognitive control than the other. Visuomotor deficits were detected only in the ALL group, with poorer performance restricted to the condition requiring the highest level of control. Significant risk factors for poorer performance were female gender and a short time since end of treatment, and a trend was found for a young age at diagnosis. A high cumulative methotrexate dose was an adverse predictive factor in girls. The results indicate that chemotherapy-induced central neurotoxicity in childhood ALL treatment is associated with higher order visuomotor control deficits. Girls appear to be particularly vulnerable.

Chemotherapy and attentional dysfunction in survivors of childhood acute lymphoblastic leukemia: effect of treatment intensity

BACKGROUND

Central nervous system (CNS) directed chemotherapy is replacing prophylactic cranial irradiation in treatment protocols for childhood acute lymphoblastic leukemia (ALL), mainly to reduce long-term neuropsychological sequelae. We evaluated the effects of chemotherapy on attentional function in survivors of ALL and examined whether possible deficits are related to treatment intensity.

METHODS

In a multi-center study, we compared attentional function in 36 children at least 1 year after finishing treatment with chemotherapy only for ALL, with a cancer control group consisting of 39 Wilms tumor patients and with 110 healthy children. We differentiated between standard- and intensified ALL treatment. The role of previously reported risk factors for neuropsychological deficits was also assessed.

RESULTS

After chemotherapy, attentional deficits were detected in patients with ALL, but not in Wilms tumor patients. Children treated according to standard ALL protocols performed worse than healthy controls on only 1 of 10 outcome measures (P = 0.004), while those who had received intensified treatment performed worse on four outcome measures (0.0001 < P < 0.004). Higher treatment intensity, young age at diagnosis, and female gender were associated with worse performance.

CONCLUSIONS

CNS-directed chemotherapy, even in the absence of cranial irradiation, is associated with attentional dysfunction in survivors of childhood ALL, particularly in case of intensified treatment protocols. These sequelae stress the importance of reducing doses of neurotoxic chemotherapy as much as possible in the design of future treatment protocols for ALL.

Attention and information processing in survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only

BACKGROUND

Omitting radiotherapy for central nervous system (CNS) prophylaxis has improved the overall quality of life for long-term survivors of childhood acute lymphoblastic leukemia (ALL). However, recent reports suggest minor cognitive impairment in survivors who received chemotherapy only.

PROCEDURE

This study focused on attentional functioning and speed of information processing in 23 children previously treated for ALL according to EORTC 58881 and EORTC 58951 protocol. Patients received intrathecal methotrexate combined with high doses intravenous methotrexate as CNS prophylaxis. Cognitive functioning was assessed with the Amsterdam Neuropsychological Tasks, a computerized attention assessment program. Variables of both speed and accuracy of the patients were compared with those obtained from 23 age- and sex-matched control children.

RESULTS

Patients were equal to control children concerning baseline speed, sustained attention, response inhibition, and response organization. However, they were significantly slower than controls in three tasks: encoding, memory search letters, and focused attention 4-letters. Interactions with the difficulty of the task were found. There were no differences in number or type of errors between groups on all tasks.

CONCLUSIONS

ALL survivors treated with chemotherapy have specific information processing difficulties. They process information slower than control children, especially when more information has to be processed or when attention has to be focused precisely. In spite of being slower, patients are equally accurate compared to control children.

The sequelae of cranial irradiation on human cognition

Cranial irradiation (CI) confers remediation of many CNS anomalies. CI, however, carries risks to cognitive performance. A wealth of data describes such deficits specifically in humans. Risk factors that promote increased susceptibility to cognitive decline have also been identified. This paper discusses and grades these risk factors, including age, gender, and the inclusion of chemotherapy, that increase the likelihood of pathologic cognitive development in the human population.

Feasibility of neuropsychological assessment in leukaemia patients shortly after diagnosis: directions for future prospective research

AIMS

To study neuropsychological functioning of newly diagnosed children with acute lymphoblastic leukaemia (ALL) within two weeks after diagnosis in order to determine the feasibility of a sibling controlled prospective study design.

METHODS

Fifty consecutive patients (median age at testing 6.6 years, range 4-12) were included in a prospective, longitudinal, nationwide study. Treatment would include intrathecal and systemic chemotherapy according to the DCLSG ALL-9 protocol. Children were evaluated with an extensive neuropsychological battery including measures of intelligence, memory, attention, language, visual-constructive function, and fine-motor abilities within two weeks after start of the chemotherapy. The control group consisted of 29 healthy siblings (median age at testing 8.2 years, range 4-12), who were tested <4 weeks after the patients' assessment.

RESULTS

Mean scores on Wechsler Intelligence Scales did not differ significantly between patients and siblings; mean IQ scores for both the patients and the controls were high average. To examine specific neuropsychological functions, norm scores based on the exact age were acquired by fitting procedures, but no significant differences were found.

CONCLUSIONS

Neuropsychological assessment of patients during early hospitalisation is feasible. The results indicate no adverse effect of illness and psychological factors on IQ and neuropsychological functioning of patients with recently diagnosed ALL. The prospective design of this study of cognitive late effects of chemotherapy will allow discrimination between adverse sequelae of disease and treatment.

Cognitive changes in children treated for acute lymphoblastic leukemia with chemotherapy only according to the Pediatric Oncology Group 9605 protocol

The purpose of this study was to examine cognitive functioning and neuroimaging in children with leukemia treated with the Pediatric Oncology Group 9605 protocol at the Children's Hospital of Eastern Ontario. Mean age at diagnosis was 4.88 +/- 2.54 years. The mean (n = 24) Wechsler Verbal and Performance IQ fell in the low-average range (87.33 +/- 15.69 and 84.83 +/- 19.11, respectively). Mean (n = 20) Verbal and Visual Memory Indexes of 82.95 +/- 15.46 and 88.30+/- 10.80, respectively, were obtained. The proportion of scores on measures of intelligence and memory falling > 1 SD below the normative mean was substantially higher than expected. Paired t-test suggested that Wechsler Verbal IQ and memory remained stable, whereas Wechsler Performance IQ declined significantly. The results of growth curve analyses replicated these findings and suggested a significant adverse effect of cumulative dosage of intrathecal methotrexate on estimated Wechsler Performance IQ. Although only two children experienced seizures, 78% of the group showed leukoencephalopathy on at least one magnetic resonance image. Reliance on seizures as a predictor of leukoencephalopathy might underestimate the incidence of neurotoxicity.

MRI morphometric and neuropsychological correlates of long-term memory in survivors of childhood leukemia

BACKGROUND

Long-term survivors of acute lymphoblastic leukemia (ALL) are reported to have post-treatment neurological changes as well as neuropsychological changes. Few studies have investigated the relationship between magnetic resonance imaging (MRI) volumetric measurements of brain regions of interest and cognitive functioning. This study examined the relationship between hippocampal volumes and long-term memory abilities in survivors of ALL.

PROCEDURE

Ten survivors of ALL and ten matched controls underwent MRI acquisition. The participants completed a battery of tests measuring both visual and verbal long-term memory. Volumetric measurements of the hippocampus were obtained by consecutive manual tracing using the NIH Image 1.52 program. Estimates of whole brain volume were also obtained.

RESULTS

No significant group differences were found in right or left hippocampi. Nor were there significant differences between the two groups on measures of long-term memory. Correlations between volumetric measurements of the hippocampus and measures of long-term memory were non-significant.

CONCLUSIONS

Our hypothesis of deficits in both long-term memory and its neural substrates was not supported. It was concluded that the hippocampus, as an early developing structure, may be less vulnerable to chemotherapy treatment. Children surviving ALL are able to retain and retrieve once learned information comparable with peers.

Newly diagnosed childhood acute lymphoblastic leukemia: update on prognostic factors and treatment

The development of effective therapy for children with acute lymphoblastic leukemia is one of the great successes of clinical hematology andoncology. Fifty years ago, childhood acute lymphoblastic leukemia was universally fatal, but current long-term event-free survival rates are nearly 80%. Despite this improved outcome, there are still many challenges facing investigators today. In some recent clinical trials, the outcome of "high-risk" patients has approached that of "lower risk" patients, suggesting that currently applied clinical factors, such as age and presenting leukocyte count, no longer identify the 20% of newly diagnosed patients who ultimately will relapse. Additionally, therapy remains nonspecific, toxic, and sometimes lethal. As more children with acute lymphoblastic leukemia survive into adolescence and adulthood, there is a need to address the late sequelae of current therapy and to develop more leukemia-specific treatments. Promising avenues of research, which may identify biologically distinctive subsets of acute lymphoblastic leukemia and potential targets for novel therapies, include studies of minimal residual disease, lymphoblast genetics (including genetic profiling studies), and host-related pharmacogenomics.

Intellectual outcome in children and adolescents with acute lymphoblastic leukaemia treated with chemotherapy alone: age- and sex-related differences

One of the most relevant concerns in long-term survivors of paediatric acute lymphoblastic leukaemia (ALL) is the development of neuropsychological sequelae. The majority of the published studies report on patients treated with chemotherapy and prophylactic central nervous system (CNS) irradiation, little is known about the outcome of patients treated with chemotherapy-only regimens. Using the standardised clinical and neuropsychological instruments of the SPOG Late Effects Study, the intellectual performance of 132 paediatric ALL patients treated with chemotherapy only was compared to that of 100 control patients surviving from diverse non-CNS solid tumours. As a group, ALL and solid tumour survivors showed normal and comparable intellectual performances (mean global IQ 104.6 in both groups). The percentage of patients in the borderline range (global IQ between 70 and 85) was comparable and not higher as expected (10% cases and 13% controls, expected 16%). Only 2 (2%) of the former ALL and 1 (1%) of the solid tumour patients were in the range of mental retardation (global IQ<70). Former known risk factors described in children treated with prophylactic CNS irradiation, like a younger age at diagnosis of ALL and female gender, remained valid in chemotherapy-only treated patients. The abandonment of prophylactic CNS irradiation and its replacement by a more intensive systemic and intrathecal chemotherapy led to a reduction, but not the disappearance of late neuropsychological sequelae.

Breast cancer chemotherapy-related cognitive dysfunction

Cognitive side effects of systemic chemotherapy have become an increasing concern among breast cancer survivors, their families, and health care professionals. A growing body of research supports the hypothesis that chemotherapy can produce long-term cognitive changes in at least a subgroup of cancer survivors. We review evidence implicating systemic chemotherapy as the cause of cognitive changes; describe the limitations due to lack of longitudinal studies and gaps in knowledge (ie, no clear mechanism by which chemotherapy can produce cognitive changes has been proposed); discuss possible factors like age, intelligence quotient/education, and psychological, genetic, and hormonal factors that might increase risk for chemotherapy-induced cognitive changes; and outline future directions for research. Such future research includes large-scale, longitudinal studies of pretreatment neuropsychological assessments, use of imaging techniques and the development of animal models to study the mechanisms of chemotherapy-induced changes in cognitive functioning, and the development of interventions to prevent or reduce the negative cognitive effects of chemotherapy

Central nervous system-directed therapy in the treatment of childhood acute lymphoblastic leukemia and studies of neurobehavioral outcome: Children's Cancer Group trials

Long-term survival rates in childhood acute lymphoblastic leukemia (ALL) have improved due, in part, to the introduction and subsequent refinements in central nervous system (CNS)-directed therapy. Studies of cognitive, motor, and behavioral functioning, which characterize the patterns and severity of CNS sequelae, are being used increasingly as measurable treatment endpoints. This paper summarizes the advances in CNS-directed therapy derived from Children's Cancer Group randomized therapeutic trials. Results from neurobehavioral outcome studies built upon these trials are also presented. A section of this review is focused on CNS-directed treatments and the neurodevelopmental outcomes of infants diagnosed with ALL, an especially high-risk patient subset. Future studies of neurobehavioral outcome are briefly elaborated in the context of current chemotherapy approaches used in the treatment of childhood ALL.