Cognitive function in long survivors of childhood acute lymphoblastic leukemia

A comprehensive model of the development of mental handicap in children treated for acute lymphoblastic leukaemia: A synthesis of the literature

Most clinical studies addressing sequelae in children with leukaemia are not theory-driven. Nonetheless, the role of different mediating biological (e.g. cranial irradiation, chemotherapy) and psychosocial variables (e.g. family functioning) has been empirically acknowledged. In these studies, a cause-effect relationship between biological variables and cognitive deficits, sometimes complex due to multiple agents, has been hypothesised. As for the psychosocial consequences, adaptation to the cancer-related stress has been the main focus, at both the individual and family levels. In this paper, we advocate the use of a global model for the development of handicap, derived from the International Classification of Impairments, Disabilities and Handicaps (ICIDH) by the World Health Organisation. This revised model proposes that handicap is the result of complex interactions between the characteristics of a person’s impairment, disabilities, and the characteristics of the environment. At each of these levels, risk/resilience factors are defined. This means that depending on the environmental obstacles they face, persons with an impairment or a disability may or may not experience a situation creating a handicap which is no longer seen as a stable status resulting from a disease to which the individual must adapt. By reviewing animal and clinical studies, current knowledge pertaining to leukaemia sequelae are integrated into the different levels defined by the model: organic impairment, disabilities, environmental obstacles, and handicap situation. Practical implications for research, policies, and individual treatments, and comparisons with existing models, are also outlined.

Cognitive outcomes following contemporary treatment without cranial irradiation for childhood acute lymphoblastic leukemia

BACKGROUND

Treatment of acute lymphoblastic leukemia (ALL) has included the use of prophylactic cranial irradiation in up to 20% of children with high-risk disease despite known cognitive risks of this treatment modality.

METHODS

Patients enrolled on the St Jude ALL Total Therapy Study XV, which omitted prophylactic cranial irradiation in all patients, were assessed 120 weeks after completion of consolidation therapy (n = 243) using a comprehensive cognitive battery. χ(2) analysis was used to compare the percentage of below-average performers among the entire ALL patient group to the expected rate based on the normative sample. Univariate logistic regression was used to estimate the effect of intensity of chemotherapy (treatment arm), age at diagnosis, and sex on the probability of below-average performance. All statistical tests were two-sided.

RESULTS

Overall, the ALL group had a statistically significantly higher risk for below-average performance on a measure of sustained attention (67.31% more than 1 SD below the normative mean for omission errors, P < .001) but not on measures of intellectual functioning, academic skills, or memory. Patients given higher intensity chemotherapy were at greater risk for below-average performance compared with those given lower intensity therapy on measures of processing speed (27.14% vs 6.25%, P = .009) and academic abilities (Math Reasoning: 18.60% vs 3.90%, P = .008; Word Reading: 20.00% vs 2.60%, P = .007; Spelling: 27.91% vs 3.90%, P = .001) and had higher parent-reported hyperactivity (23.00% vs 9.84%, P = .018) and learning problems (35.00% vs 16.39%, P = .005). Neither age at diagnosis nor sex was associated with risk for below-average cognitive performance.

CONCLUSIONS

Omitting cranial irradiation may help preserve global cognitive abilities, but treatment with chemotherapy alone is not without risks. Caregiver education and development of interventions should address both early attention deficits and cognitive late effects.

Neurodevelopmental functioning in very young children undergoing treatment for non-CNS cancers

OBJECTIVE

We initiated a prospective study of very young children with cancer, in comparison with matched healthy children, to investigate neurodevelopmental consequences of non-CNS cancers and treatment.

METHODS

A total of 61 children (≤42 months) with non-CNS cancers and 61 matched controls underwent an identical age-appropriate neuropsychological test battery.

RESULTS

Children with cancer manifested deficits compared to healthy controls in motor, mental, and language development, but were similar to controls in cognitive representational abilities and emotional relationships in interaction with their mothers. Better physician-rated health status at diagnosis and mother-rated behavioral status 1 month prior to assessment were associated with better motor and mental performance in the cancer group.

CONCLUSIONS

This study identifies deficits as well as spared functions in children with non-CNS cancers; the results suggest ways parents and healthcare professionals may plan specific remediations to enhance quality of life in young cancer survivors.

Effects of chemotherapy on neurocognitive function in children with acute lymphoblastic leukemia: a critical review of the literature

Chemotherapy-only treatment has increasingly become the standard of treatment for childhood acute lymphoblastic leukemia (ALL). The objective of this review is to assess the present state of knowledge of the neurocognitive effects of central nervous system (CNS)-directed chemotherapy in children with ALL, and to formulate directions for future research. We performed a review of studies published since 1997, that included an ALL group treated with chemotherapy only and a control group. Twenty-one studies met our inclusion criteria. There is evidence of subtle long-term neurocognitive deficits survivors of childhood ALL after treatment with chemotherapy only. These involve mainly processes of attention and of executive functioning, while global intellectual function is relatively preserved. Young age at diagnosis and female sex emerged as risk factors.

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.

Long-Term Health Status Among Survivors of Childhood Cancer: Does Sex Matter?

Increasing numbers of children diagnosed with cancer will survive their primary malignancy. Within this growing population of long-term survivors, considerable effort has been put forth to identify treatment-related risks for adverse health-related outcomes, such as exposure to alkylating agents, anthracyclines, radiotherapy, and surgery. Patient sex has been identified as a risk factor for numerous long-term adverse outcomes, with female sex more commonly associated with higher risks. In this article, we review the literature, which generally supports associations between female sex and cognitive dysfunction after cranial irradiation, cardiovascular outcomes, obesity, radiation-associated differences in pubertal timing, development of primary hypothyroidism, breast cancer as a second malignant neoplasm and suggests an increased prevalence for the development of osteonecrosis among females. Results of this review support future investigations to further define sex as a risk factor for other common treatment-specific exposures and outcomes. Additionally, research should focus on understanding the underlying biologic and physiological basis of these sex-specific risks. Historically, evidence from both basic science and clinical research has been used to develop risk-stratified therapy, allowing reduction of toxic therapies to low-risk patients without compromising overall survival. With greater knowledge of sex-specific risks, the potential application of sex-specific therapy designed to avoid poor long-term adverse outcomes may become a viable strategy.

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.

A meta-analysis of the neurocognitive sequelae of treatment for childhood acute lymphocytic leukemia

BACKGROUND

Impaired neurocognitive functioning is one increasingly recognized long-term consequence of childhood ALL treatment. However, research findings have been inconsistent regarding the domains affected and the degree to which they are compromised.

PROCEDURE

A comprehensive meta-analytic review of the long-term neurocognitive effects of childhood ALL was conducted. Studies were included if they were published in English, reported original quantitative data on the post-treatment neurocognitive functioning of childhood ALL patients in first remission and control groups, and used neurocognitive measures with adequate psychometric properties and published normative data.

RESULTS

Data from 28 empirical studies yielding 13 effect sizes across nine domains were extracted and analyzed. All effects were negative (g = -0.34 to -0.71), demonstrating that ALL survivors consistently experienced significant deficits in intellectual functioning, academic achievement, and specific neurocognitive abilities compared to control groups. The role of potential moderators, including treatment with cranial irradiation, age at time of diagnosis, and time since treatment ended, was examined. However, no effects emerged as clearly and consistently moderated by these variables.

CONCLUSIONS

The results from this meta-analysis suggest that declines in both global and specific areas of areas of neurocognitive functioning occur as a result of contemporary ALL treatment. Such deficits have significant implications for survivors' academic achievement and overall quality of life. Neurocognitive assessment plays a critical role in determining what remedial or specialized instruction is needed in childhood ALL survivors and should be included as a standard part of long-term follow-up care.

Almost normal cognitive function in patients during therapy for childhood acute lymphoblastic leukemia without cranial irradiation according to ALL-BFM 95 and COALL 06-97 protocols: results of an Austrian-German multicenter longitudinal study and implications for follow-up

In a multicenter study the authors prospectively investigated neurocognitive function in childhood ALL patients. Sixty-six patients (mean age at diagnosis 7.9 +/- 3.6 years, 34 female), treated with repeated intrathecal and systemical methotrexate administrations without cranial irradiation, underwent psychometric testing for intelligence, concentration, and visual-motor integration postdiagnosis and after reinduction therapy. Although there was a statistically significant decline of intellectual function after reinduction therapy for younger patients and girls (IQ scores still within normative data range), there were no differences in visual-motor performance and concentration over the time of induction therapy. Thus, neurocognitive examination should focus on younger ALL patients and girls.

Dietary essential fatty acids and gender-specific behavioral responses in cranially irradiated rats

Specific memory deficits, reduced intellectual processing speed, and a variety of social and behavioral problems have been implicated as long-term effects of cranial radiation therapy (CRT). These deficits are thought to be related to changes in brain cytology and structure associated with microvascular aberrations. N-3 fatty acids may serve as protectants in pediatric patients who receive CRT for brain tumors. Timed-pregnant rat dams were fed one of four diets that were identical in all respects, except for their essential fatty acid content. The dams were placed on these diets at the beginning of the third trimester of gestation and their pups remained on them throughout the study. The rats' behavioral response as judged by acoustic startle response (ASR) and neurocognitive response (performance in a radial maze, RM) were evaluated in relation to diet, gender, and CRT. The following hypotheses were tested: (1) female rats will show greater CRT-induced neurocognitive and behavioral deficits; (2) dietary n-3 fatty acids will diminish CRT-induced neurocognitive and behavioral deficits; (3) gender-specific differences would be dampened by n-3 fatty acids in the diet. All three hypotheses were partially supported. These findings are discussed in light of the potential neuroprotective effects of n-3 fatty acids.

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.

Educational attainment among survivors of childhood cancer: a population-based cohort study in Denmark

We identified 2384 patients in the Danish Cancer Register in whom cancer had been diagnosed in 1960–1996 before they reached the age of 20 and compared them with 53 143 sex- and age-matched controls identified from the Register of Population Statistics. Complete education records and demographic and socioeconomic information for the period 1980–2000 were obtained for both cohorts from Statistics Denmark. The rate ratio (RR) for educational attainment was estimated by discrete-time Cox regression analyses. An overall reduction in attaining basic education was found (RR, 0.90; 95% confidence interval, 0.83–0.96). Female survivors of central nervous system (CNS) tumours showed the largest educational deficit (RR, 0.55; 95% confidence interval, 0.37–0.82). Non-CNS tumour survivors attained education as controls at most levels. When the analyses were conditioned on completion of youth education, further educational attainment was not reduced for any group of survivors. These findings confirm that only survivors of CNS tumours in childhood experience significant educational deficits. The deficit was mainly seen among persons whose tumour was diagnosed before they reached the level of secondary education.

Verbal cognitive functioning and learning in girls treated for acute lymphoblastic leukemia by chemotherapy with or without cranial irradiation

Neuropsychological problems have frequently been reported following treatment of Acute Lymphoblastic Leukemia (ALL), however, partly because of the heterogeneity of the previously studied samples, the specific nature of these deficits is still a matter of debate. These problems, however, appear to be related more to the combination of cranial radiation therapy (CRT) and intrathecal chemotherapy (ITC) than to ITC alone. In this study, we evaluated a homogenous group of 19 girls between the ages of 7 and 11 years, 30 months after the completion of treatment. Nine received cranial radiation and chemotherapy and 10 were treated with chemotherapy alone. The patients were compared to 10 normal healthy controls. Neuropsychological tests included the Wechsler Intelligence Scale for Children-Third Edition (WISC-III), the California Verbal Learning Test-Children's Version (CVLT-C), and the Calculation and Passage Comprehension subtests of the Woodcock-Johnson Psycho-Educational Battery-Revised. Results confirmed the presence ofa verbal learning deficit in ALL girls treated with the combination of ITC and CRT. The ITC and CRT group scored significantly lower than the healthy controls on the Passage Comprehension subtest and on 5 of the 6 verbal subtests of the WISC-III. Furthermore, compared to nonirradiated patients and healthy normal controls, the ITC and CRT group was impaired on the Freedom from Distractibility index of the WISC-III, indicating an auditory-verbal attention deficit. On the CVLT-C, the ITC and CRT group was particularly impaired on the second half of the learning trials compared to the other two groups, showing a plateau in their performance. The ITC group was not different from the healthy control group, suggesting a less detrimental effect of the ITC alone on verbal abilities. Globally, these results indicate a deficit affecting auditory attention and verbal learning in girls who receive ITC and CRT, which may suggest the necessity for special educational assistance for these children.

CNS late-effects after ALL therapy in childhood. Part III: neuropsychological performance in long-term survivors of childhood ALL: impairments of concentration, attention, and memory

PURPOSE

To date, the event free survival (EFS) after treatment of childhood acute lymphoblastic leukemia (ALL) attains 80%. The survivor group is growing steadily. Therefore, the primary purpose of our study is to define the neuropsychological function and to describe which central nervous system (CNS) functions are impaired following the German ALL-BFM and COALL protocols for CNS-negative patients.

PATIENTS AND METHODS

In a cross-sectional multicenter study 121 subjects, long-term survivors of childhood ALL in first continuous complete remission were investigated. Seven years ago, the subjects were treated as standard or medium risk patients according to ALL-BFM 81, ALL-BFM 83, or COALL 82 protocols, receiving comparable treatments. According to different CNS-prophylaxes, two subgroups were compared in the study: the non-cranially irradiated MTX-group (methotrexate-group) (n = 38) and the cranially irradiated RT-group (radiotherapy-group) (with MTX i.th.) (n = 83). Intellectual and cognitive abilities of these groups were evaluated using standardized psychometric techniques. The Kaufman factors Verbal Comprehension, Perceptual Organisation and Freedom from Distractibility were calculated. Demographical and clinical data collected at the time of the diagnosis were compared between both groups. The different prognoses for patients within both groups were taken into account using a defined risk factor. Analysis of variance was conducted to relate intellectual performance to age, gender, and CNS-treatment.

RESULTS

The RT-group exhibited a lower Full Scale IQ than the MTX-group (101.2 +/- 15.9 vs. 109.9 +/- 14.9, P = 0.031). Particularly for the Kaufman factor Freedom from Distractibility the RT-group showed the lower scores (96.9 +/- 14.1 vs. 105.5 +/- 12.6, P = 0.037). Significant interactions between gender and CNS prophylactic treatment were observed for Full Scale IQ (P = 0.008), Verbal IQ (P = 0.012), Performance IQ (P = 0.024), Verbal Comprehension (P = 0.004), and Perceptual Organisation (P = 0.032).

CONCLUSIONS

Cranial irradiation in combination with MTX therapy was associated with deficits in attention, concentration, and the ability of sequencing and processing, measured by the Kaufman factor Freedom from Distractibility. Our results support the strategy of avoiding prophylactic CNS irradiation in low risk patients.

Long-term sequelae of therapy for childhood acute lymphoblastic leukaemia

Childhood ALL has provided the model for basic therapeutic principles in the past and now provides the model for late effects studies. Common threads which run throughout the literature in this area of clinical research are the importance of young age with increased vulnerability to long-term treatment induced sequelae and the relatively large contribution of radiation as compared with chemotherapy in the pathogenesis of adverse sequelae. Previous retrospective studies of long-term childhood ALL survivors focused on neuropsychologic changes and anatomic changes in the CNS after cranial irradiation. More recent retrospective studies have made the following new observations: (i) the high frequency of significant short adult stature in those less than 6 years of age at diagnosis who received 24 Gy cranial irradiation; (ii) actuarial risk of 2.5% of developing a second malignancy with approximately one-half of secondary malignancies occurring in the CNS in children 5 years of age or less who received cranial irradiation; (iii) the association of secondary ANLL with epipodophyllo-toxin use, and (iv) delayed cardiac toxicity despite anthracycline dosage reduction. Current therapy regimens, especially in high-risk patients, are both more successful and more intensive than those used in the past. While it will be another decade before many of the long-term sequelae begin to emerge, one can anticipate, based on current experience, some of the problems that will occur.

Intellectual function in long-term survivors of childhood acute lymphoblastic leukemia: protective effect of pre-irradiation methotrexate? A Childrens Cancer Study Group study

Having demonstrated in a laboratory model that the neurotoxicity of CNS irradiation can be ameliorated with pre-irradiation methotrexate, we retrospectively compared two methods of CNS prophylaxis in childhood acute lymphoblastic leukemia which differed only in the timing of intrathecal methotrexate and radiotherapy. The results of standard IQ tests conducted 2-11 years after 24 Gy of cranial radiotherapy were obtained in 72 patients, of whom 27 had pre-irradiation methotrexate and 45 did not (control group). The two groups were otherwise comparable. In girls, the full-, performance-, and verbal-scale IQ scores were consistently higher in the pre-irradiation methotrexate group than in the corresponding control group (P less than 0.025). Among girls less than 5 years of age when irradiated, the mean IQ scores were 25-29 points higher after pre-irradiation methotrexate than after the control treatment (P less than 0.0007). These results suggest that pre-irradiation methotrexate may help prevent CNS radiotoxicity in children, and that the benefit is dependent on patient age and gender.

Brain tumours under the age of three. The price of survival. A retrospective study of 20 long-term survivors

Between 1975 and 1989, 98 children with brain tumours under the age of three at time of diagnosis were entered into a retrospective study. Twenty of them are alive and free of tumour more than five years after treatment and were evaluated in this study. Thirteen tumour localizations were infratentorial and 7 were supratentorial. A histological examination was performed in 15 patients: 5 ependymomas, 6 medulloblastomas and 4 astrocytomas were identified. Fifteen patients underwent surgical removal of tumour, all but one received radiotherapy and 8 were given chemotherapy. Only two children have not late effects. Analysis of long-term sequelae in survivors showed central endocrinopathies in 14 (70%), a neurological handicap in 13 (65%) and impaired cognitive functions in 17 (85%). Irradiation was clearly responsible for mental sequelae in 7 patients and endocrinopathies in 6 patients. The other possible causes are tumour injury, hydrocephalus or surgery. The risks incurred with radiotherapy and advances in infant brain tumour therapy are discussed.