Long-term consequences of CNS treatment for childhood cancer, Part I: Pathologic consequences and potential for oncogenesis

Diffusion Tensor Imaging and Neurobehavioral Outcome in Children With Brain Tumors Treated With Chemotherapy

BACKGROUND

Childhood brain tumor survivors (CBTS) often experience treatment-related neurocognitive deficits affecting quality of life (QOL), but systemic chemotherapy contributions to outcomes are unclear. Our objective was to relate brain tissue changes to neurocognitive and QOL effects after systemic myeloablative chemotherapy with autologous hematopoietic progenitor cell rescue in CBTS.

PROCEDURE

Regional brain volumes and diffusion tensor indices were correlated with neurocognitive, behavioral, and QOL measures, and compared between 8 CBTS (mean age 8.5 years, mean age at diagnosis 32 months), and 9 healthy controls (mean 9.3 years).

RESULTS

Overall QOL, school, and psychosocial functioning were significantly lower in patients (P < .05). Most patients scored within normative ranges on neurocognitive and behavioral assessment. Elevated mean diffusivity and decreased fractional anisotropy, indicating gray and white matter injury, respectively, appeared in memory and executive functioning areas. Low scores on Inhibition on the Neuropsychological Assessment-II were correlated with elevated mean diffusivity in prefrontal cortex.

CONCLUSIONS

Brain injury, decreased QOL, and to a lesser extent, executive functioning deficits appear in CBTS treated with myeloablative chemotherapy and autologous hematopoietic progenitor cell rescue. Early cognitive and psychological assessment and intervention are warranted in this population.

The role of up-front radiation therapy for incompletely resected pediatric WHO grade II low-grade gliomas

The purpose of this study was to assess the impact of early radiation therapy and extent of surgical resection on progression-free survival (PFS) and overall survival (OS) in children with WHO grade II low-grade gliomas (LGGs). We conducted a historical cohort study of 90 patients, ages 21 or younger, diagnosed with WHO grade II LGGs between 1970 and 1995. Median follow-up for surviving patients was 9.4 years (range, 0.5-22.6 years). Tests for variables correlating with OS and PFS were conducted by using log-rank tests and Cox proportional hazards models. Eleven patients underwent gross total resections (GTRs), 43 had subtotal resections, and 34 underwent biopsy only at diagnosis. Two patients underwent biopsy at time of recurrence. Of the 90 patients, 52 received radiation as part of their initial therapy following diagnosis (early-RT group). The overall five-year PFS and OS rates +/- SE were 56% +/- 5% and 90% +/- 3%, respectively. Ten-year PFS and OS rates were 42% +/- 6% and 81% +/- 5%, respectively. For patients older than three years and without GTRs, administration of early radiation did not appear to influence PFS or OS (P = 0.98 and P = 0.40, respectively; log-rank test). This was confirmed by multivariate analyses (P = 0.95 and P = 0.33 for PFS and OS, respectively). Of the 11 patients with GTRs, disease progressed in only two, and all were alive with no evidence of disease at last follow-up. Patients who underwent GTRs had significantly longer PFS (P = 0.02), but did not have significantly improved OS. Excellent long-term survival rates were achieved for children with WHO grade II LGGs. We were unable to demonstrate a benefit for administering radiation as part of initial treatment. An outcome benefit was seen with greater extent of resection.

The Effect of Radiation Therapy on Normal Tissue Function

As more patients are treated for their primary malignancy with cure or increased disease-free intervals, injury to normal tissues will become more detectable and an important endpoint for study. Future protocols will probably be modified based on toxicity endpoints. In Hodgkin's disease, current protocols use response-based treatment strategies to limit therapy. The objective is to provide the same level of tumor control and follow normal tissue endpoints for outcome analysis. DVH analysis has improved the ability to analyze endpoint data for normal tissues. These image-guided platforms will provide the infrastructure needed to continue efforts in improving the delivery of radiation therapy.

Long-term effects of radiation therapy on cognitive and endocrine function in children with leukemia and brain tumors

BACKGROUND

As the number of long-term survivors of childhood cancer has grown, it has become increasingly clear that central nervous system therapy may have serious long-term effects on cognition and endocrine function. These complications have been studied most extensively in children with brain tumors and leukemia.

REVIEW SUMMARY

Children with acute lymphoblastic leukemia previously treated with cranial irradiation are at risk for cognitive decline. Chemotherapy-only regimens, which rely on high-dose frequently administered methotrexate, are also associated with producing cognitive dysfunction. Children irradiated for brain tumors are even more vulnerable. Risk factors include perioperative morbidity, young age, large-volume high-dose cranial irradiation, supra-tentorial location of tumor, moyamoya syndrome, and leukoencephalopathy. Cognitive decline is progressive over at least a decade. The most common radiation-induced endocrinopathies are hypothyroidism and growth hormone deficiency. Treatment effects on growth are multifactorial and include growth hormone deficiency,spinal shortening, precocious puberty, undetected hypothyroidism,and poor nutrition. Fifty percent to 80% of children treated with craniospinal radiation for brain tumors will experience growth failure. In hopes of reducing neurotoxicity, current treatments limit the dose and volume of radiation while adding chemotherapy. Results have not been uniformly positive, however, and may increase toxicity in some cases.

CONCLUSIONS

The standard of care in 2004 is that children who have been treated for brain tumors and leukemia should be monitored for cognitive and endocrine dysfunction. Until effective non-neurotoxic treatment is identified, long-term effects assessments are essential to maximize the quality of life of survivors of childhood cancer.

Radiation as a Nervous System Toxin

Neurotoxicity from radiation can range widely and produce effects that may include (1) small absolute increases in cancer risks, (2) subtle effects on higher level functioning in some individuals, (3) severe cognitive impairment in some individuals, (4) severe focal injury tat may include necrosis or irreversible loss of function, and (5) overwhelming and rapidly fatal diffuse injury associated with high-dose, whole-body exposures. An understanding of the implications of nervous system exposure to radiation can guide efforts in radiation protection and aid in the optimization of the medical uses of radiation.

Mesial temporal sclerosis in acute childhood leukemias

PURPOSE

Although seizures are relatively common in acute childhood leukemias, evolution into epilepsy is rare.

METHODS

We describe three patients with acute leukemias who received chemotherapy. One patient also received cranial irradiation.

RESULTS

All three developed recurrent complex partial seizures after initiation of chemotherapy. Initial neuroimaging performed in two patients was normal. Subsequent neuroimaging in all three revealed mesial temporal sclerosis.

CONCLUSIONS

The association of mesial temporal sclerosis in acute childhood leukemias has not been previously described and may be secondary to antileukemic treatment and recurrent seizures.

Acromegaly: a new therapy

BACKGROUND

The treatment of acromegaly can be challenging. Despite a multimodality approach (surgery,radiation, dopamine agonists, somatostatin analogs), many patients do not achieve normalization of serum insulin-like growth factor I (IGF-I) concentrations.

METHODS

The author discusses the characteristics and indications of pegvisomant therapy for patients with acromegaly and compares the use of this newly developed GH receptor antagonist with other pharmacological agents such as somatostatin and dopamine agonists.

RESULTS

Therapy with pegvisomant allows serum IGF-I concentrations to be normalized in up to 97% of patients with acromegaly, including those who have failed other treatment modalities. With this agent,circulating GH levels increase as a result of the drop in IGF-I levels. The rise is rapid (within 2 weeks) and does not appear to be progressive over time.

CONCLUSIONS

Published studies have shown pegvisomant to have efficacy in the treatment of acromegaly. As it appears to be well tolerated and safe, this novel compound may be an important therapeutic option for patients with acromegaly. Additional study of this novel agent and its mode of action is warranted.

Pseudomigraine with prolonged aphasia in a child with cranial irradiation for medulloblastoma

We report a 12-year-old child with episodes of migraine-like headaches with visual and motor auras a year after the surgical resection and radiation therapy for medulloblastoma The patient presented with an episode of headache, prolonged aphasia, right hemiparesis, status epilepticus, and salt wasting. There was no evidence of a structural lesion. The neurologic deficits resolved over a period of 6 weeks. Because of the progressive deterioration in neurologic deficits, the patient underwent an extensive battery of laboratory tests and multiple neuroimages, all of which were normal. The unusually prolonged neurologic deficit in this patient without demonstrable structural lesions and his eventual complete recovery were most likely caused by ischemia in the left hemisphere secondary to vasospasm. This presentation mimics migraine headache. Evidence suggesting that this represents a long-term complication of treatment of children with central nervous system neoplasia is presented.

Glial differentiation predicts poor clinical outcome in primitive neuroectodermal brain tumors

Primitive neuroectodermal tumors (PNETs) of the central nervous system, including medulloblastomas (PNET/MB), are the most common malignant brain tumor of childhood. These tumors often express proteins characteristic of glial differentiation (glial fibrillary acidic protein, GFAP), neuronal differentiation (neurofilament proteins, NFPs), and/or photoreceptor differentiation (retinal-S antigen). To identify biological factors of prognostic significance in PNETs, the expression of glial, neuronal, or photoreceptor antigens was evaluated in the tumor specimens of 86 patients with PNETs by immunohistochemistry after microwave antigen enhancement. Patterns of differentiation were then compared with patient relapse-free survival. Multivariate analysis of PNET immunohistochemistry and clinical variables indicated GFAP expression conferred a 6.7-fold greater risk of relapse than tumors that did not express GFAP or NFPs. Increased risk of relapse was directly related to the amount of GFAP expression. Tumors exhibiting clumps or sheets of GFAP-staining cells were associated with a 3.0-fold increased risk of relapse compared with tumors that did not express GFAP, irrespective of immunohistochemical evidence of other differentiation, while scattered GFAP staining was not associated with increased risk of relapse. These findings indicate that expression of GFAP in PNETs has prognostic power comparable with the most significant clinical factors currently used to predict clinical outcome.

Intracranial choriocarcinoma causing precocious puberty and cured with combined modality therapy

Precocious puberty can be caused by hormonally active tumours, which may arise intracranially. Treatment of these intracranial lesions traditionally involves biopsy and radiotherapy. Chemotherapy has been used recently, although radiotherapy has been given irrespective of the response to chemotherapy. We report a case of precocious puberty in an 8 year old boy due to a malignant intracranial germ cell tumour. Although one could speculate that he was cured by such combined modality therapy, the patient was left with several long-term problems. Radiotherapy was a major cause of these complications. Radiotherapy is now thought unnecessary for most extracranial germ cell tumours, as chemotherapy alone is curative in most patients. Therefore it seems appropriate to consider the elimination of radiotherapy for patients with intracranial disease.