Postirradiation cerebellar glioma. Case report

Radiation-induced brain tumours after central nervous system irradiation in childhood: a review

OBJECTS

Radiation-induced cerebral tumours constitute a significant risk for subjects undergoing radiotherapy for the management of cerebral neoplasms. Age-related cerebral vulnerability could be a specific factor in the genesis of these complications.

METHODS

The pertinent literature of both paediatric and adult series has been reviewed. Three personal cases were added.

RESULTS

One hundred forty-two paediatric second brain tumours were evaluated. Out of them, 69 were malignant gliomas, 33 meningiomas, 8 sarcomatous lesions and 13 low-grade astrocytomas. The average latency period for the appearance of the second tumour was 8 years. Among the second tumours occurring in adults, meningioma is the most common. In this subgroup, the latency period ranged between 16 and 30 years.

CONCLUSION

Paediatric radiation-induced brain tumours differ from the adult counterpart for both the histological subtypes. These figures indicate a specific vulnerability of the infantile brain demonstrated by the most frequent occurrence of highly malignant lesions.

Radiation-induced malignant gliomas: is there a role for reirradiation?

PURPOSE

To review the literature regarding the role of radiotherapy (RT) in the treatment of patients with radiation-induced malignant gliomas (RIMGs).

METHODS AND MATERIALS

A PubMed search of English-language articles dealing with RIMG was performed, yielding 52 articles with 92 patients available for review.

RESULTS

Initial tumor types treated with RT included brain tumor in 37 patients (40%), acute lymphoblastic leukemia in 33 (36%), benign disease in 11 (12%), and other in 11 (12%). Median time from RT to development of an RIMG was 8.75 years (range, 2.5-61 years). The RIMG occurred within 10 years after RT in 81% of patients with acute lymphoblastic leukemia/lymphoma, 59% of patients with brain/other, and 18% of patients with benign conditions (p = 0.002). Type of RIMG was glioblastoma in 69 (75%) and anaplastic astrocytoma in 23 (25%). One-, 2-, and 5-year overall survival rates were 29.3%, 7.3%, and 0% for patients with glioblastoma and 59.7%, 30.3%, and 20.2% for patients with anaplastic astrocytoma. For the 85 patients with data regarding treatment for RIMG, 35 underwent reirradiation to a median dose of 50 Gy (range, 30-76 Gy). For patients undergoing reirradiation, 1-, 2- and 5-year overall survival rates were 58.9%, 20.5%, and 6.8%. For those not undergoing reirradiation, they were 15.1%, 3%, and 0% (p = 0.0009).

CONCLUSIONS

The RIMG appeared earlier in patients treated for leukemia and lymphoma and latest for those treated for a benign condition. Patients who underwent reirradiation for RIMG have longer survival times compared with those not receiving RT.

Prognosis of cerebellar astrocytomas in children

OBJECTIVE

Our main objective is to review a large series of cerebellar astrocytomas in children and evaluate the outcome of the patients depending on astrocytoma class. The effect of astrocytoma characteristics on the children's prognosis was determined by grouping a series of cerebellar astrocytomas by their location, radiological aspect, size, and histology and determining whether this was related with outcome.

MATERIALS AND METHODS

Two hundred and three children with cerebellar astrocytomas were retrospectively reviewed, and their tumors were classified by location, macroscopic radiological appearance, size, and histology. We have distinguished between patients operated before and after 1974 because of the introduction of new diagnostic (computed tomography, magnetic resonance) and more sophisticated treatment techniques after this year (microsurgery, laser, cavitron, etc).

RESULTS

Our patients' results were classified according to the Lapras scale/classification as normal, with some neurological deficit but able to lead a normal life, and those with severe post surgical deficits. Recurrences and mortality were also noted. Normal or good results were obtained in 111 patients, some neurological deficit in 55, and severe deficits in nine. There were six recurrences and 22 deaths because of the disease.

CONCLUSIONS

Two main factors affected prognosis. One was whether the tumor was completely resected or not; this was the treatment in most cases in this series. The second factor was the location, size, and macroscopic appearance of the tumor. The best prognosis was associated with being located in one hemisphere, being cystic, being cystic with a posterior nodule, and/or being small.

Anaplastic oligoastrocytoma: previous treatment as a possible cause in a child with acute lymphoblastic leukemia

INTRODUCTION

The authors present a 14-year-old patient who developed an anaplastic oligoastrocytoma of the left parietal lobe 9 years after a successful treatment of acute lymphoblastic leukemia (ALL). He had a history of induction chemotherapy, intrathecal methotrexate and prophylactic whole brain irradiation (1,800 cGy in 10 fractions over 2 weeks).

DISCUSSION

Radiation-induced neoplasia is suggested to be the late complication of ALL treatment, and evaluation of large clinical series revealed a relationship between young age at ALL diagnosis (<6 years) and increased high-grade glioma occurrence risk.

CONCLUSION

The authors have reviewed previously reported cases of secondary central nervous system malignancies focusing on age at ALL diagnosis, and they think that synergistic action of therapeutic modalities could have played a role in the oncogenetic process. Detailed systematic radiological follow-up should be done in these patients especially if a personal history of cranial irradiation is present.

Glioblastoma multiforme following cranial irradiation and chemotherapy for acute lymphocytic leukaemia. Report of 3 cases

The most common secondary neoplasms which occur following cranial radiation therapy are sarcoma and meningioma. The occurrence of glioblastoma multiforme following radiation and chemotherapy in acute lymphocytic leukaemia (ALL) is rare. We report 3 cases of glioblastoma multiforme in children developing 11-72 months following completion of chemotherapy/radiotherapy for ALL. The exact cause for the development of glioblastoma multiforme following therapy for ALL is not clear. A genetic predisposition may be essential for the occurrence of such a highly malignant primary brain tumour in leukaemia patients, irrespective of radiation and/or chemotherapy. The pathogenesis and surgical management are discussed, and the literature on the subject is reviewed.

Radiation-induced gliomas: report of 10 cases and review of the literature

BACKGROUND

Radiotherapy and more recently radiosurgery represent important therapeutic methods for the treatment of tumors and arterovenous malformations affecting the central nervous system, even though several significant side-effects have been described (radionecrosis, tumors, etc.). Gliomas induced by radiation therapy are decidedly unusual, and the first descriptions of this association only appeared in the 1960s.

METHODS

The pertinent literature was reviewed to yield 116 cases in which a glioma developed after radiotherapy for cranial pathologies (included 10 personal cases treated in our Institution). One of our patients had undergone radiosurgery for a cavernous angioma.

RESULTS

Patients who developed a radiation-induced glioma were younger, as a group, than those affected with so-called "spontaneous" gliomas. The tumor originated in the previously irradiated area, after average doses of 32 Gy and an average latency period of 9.6 years in accordance with the findings reported by the authors and in our experience as well. Radiotherapy had most frequently been performed for acute lymphoblastic leukemia. Our Case 10 is the fourth case of intracranial tumor arising after radiosurgery to be described in the literature.

CONCLUSIONS

Though rare, gliomas may represent a late complication of radiation treatment. The behavior of the radiation-induced variety of glioma does not seem to differ significantly from that of its "spontaneous" counterpart. Late complications of the radiosurgery are probably underestimated because of the relatively recent introduction of this technique. On the contrary, these should be scrupulously evaluated when deciding whether to employ this method for therapeutic purposes for relatively benign or congenital lesions (which generally affect young patients with a long life expectancy).

Gamma knife radiosurgery and its possible relationship to malignancy: a review

✓ The question has been raised recently whether gamma knife radiosurgery (GKS) can induce secondary neoplasia. Because there is little or no detailed knowledge about this potential complication, background information culled from the radiotherapy literature is reviewed as a guide to the clinical situations in which radiotherapy may induce secondary neoplastic change. Available case reports are then reviewed and discussed against the background of the current knowledge. On the basis of the review, the following suggestions are proposed on how to limiting the extent of this complication, document its frequency, and inform patients. It should be remembered that: the benefits of GKS are great; its alternatives also have risks; there often are no alternatives to GKS; follow-up documentation should be pursued more actively so that, if possible, no patient falls through the net; practitioners should be proactive in defining the problem, and genetic analysis of tumor biopsy specimens obtained in patients who will undergo or have undergone GKS should become routine; the extent of secondary neoplasia is not known; and patient information should be guided by what is known rather than by what is feared.

Classification and grading of low-grade astrocytic tumors in children

This article reviews current perspectives in the classification and grading of astrocytomas in children and calls attention to several histologically distinct groups of low-grade tumors that characteristically arise during childhood. Recognition of these tumors and the range of histological features that they may exhibit is essential for making rational assessments regarding their expected behavior and, more importantly, for guiding therapeutic intervention. For example, pleomorphic xanthoastrocytoma, which may exhibit "anaplastic" features, generally carries a relatively favorable prognosis and should not be classified with other high-grade gliomas, such as anaplastic astrocytoma and glioblastoma multiforme. Similarly, the finding of anaplastic features, such as vascular proliferation or necrosis, in pilocytic astrocytomas does not automatically portend the unfavorable prognosis that such features would imply for "diffuse" astrocytomas. Increased appreciation of the morphological diversity of astrocytomas in children should help to improve the management of children with low-grade astrocytic tumors by avoiding potentially dangerous overtreatment of otherwise indolent lesions.

Radiation-induced gliosarcoma. Case report and review of the literature

A 13-year-old boy presented with a cerebral gliosarcoma 12 years after having acute lymphoblastic leukemia treated by chemotherapy and central nervous system prophylaxis treated by radiation therapy (24 Gy) and intrathecal methotrexate. A review of the literature disclosed 129 possible radiation-induced gliomatous and/or sarcomatous brain tumors: namely, 89 gliomas, 36 sarcomas, and four gliosarcomas, including the present case. An analysis of these cases revealed several characteristics that differentiate them from similar spontaneous brain tumors, thus providing arguments for the carcinogenic effect of radiation therapy on intracranial tumors.

The significance of atypia and histologic malignancy in pilocytic astrocytoma of the cerebellum: a clinicopathologic and flow cytometric study

Biologically malignant pilocytic astrocytomas are rare. Precise morphologic criteria permitting their identification and clinically meaningful distinction from more ordinary pilocytic astrocytomas have not been developed. The histologic grading schemes applied to fibrillary astrocytomas--ones based on nuclear atypia, increased cellularity, mitotic activity, endothelial proliferation, and necrosis--are thought not to correlate with prognosis in pilocytic astrocytomas. Nonetheless, these features were systematically sought in 107 cerebellar pilocytic astrocytomas, four of which were histologically malignant. The clinical, morphologic, and flow cytometric features of these cases were studied. The incidence of histologic malignancy occurring spontaneously in otherwise typical pilocytic astrocytomas was 0.9%; that occurring after radiation was 1.8%. The four histologically malignant tumors occurred in two males and two females, ages 6 to 18 years. All showed increased mitotic activity (three to five mitoses per high-power microscopic field [250x]). Endothelial proliferation and necrosis were present in three and two cases each. DNA ploidy analysis showed the spontaneously occurring malignant-appearing tumors to be aneuploid, whereas both previously radiated tumors were tetraploid; 5% to 11% of cells were in S phase. The appearance of histologic malignancy in pilocytic astrocytoma is rare and less reliably correlated with prognosis than in patients with fibrillary astrocytomas. Essential features of such tumors include a high mitotic index and perhaps a high percentage of cells in S phase.

Brain tumors following cure of acute lymphoblastic leukemia

The majority of children with acute lymphoblastic leukemia can be cured with effective modern day therapy. However, more and more long term sequelae including carcinogenic potential of the treatment are being recognised. We report two children who developed acute lymphoblastic leukemia at the age of 4 and 5 years respectively and were successfully treated. They developed meningioma and astrocytoma at 9 and 3 years respectively after completion of therapy. Both were treated surgically and the patient with astrocytoma also received radiotherapy. Both are now free of disease 19 months after diagnosis of second neoplasm.

Primitive neuroectodermal tumors after prophylactic central nervous system irradiation in children. Association with an activated K-ras gene

Three patients had supratentorial malignant brain tumors 7 to 9 years after prophylactic central nervous system (CNS) treatment for acute lymphocytic leukemia or malignant T-cell lymphoma. Therapy was administered at the age of 3 to 8 years and included cranial irradiation (total dose, 1800 to 2400 cGy) and intrathecal methotrexate. The brain tumors had histologic and immunohistochemical features of primitive neuroectodermal tumors (PNET), including neuroblastic rosettes, rhythmic arrangement of tumor cells, and immunohistochemical expression of glial, and in one patient neuronal, marker proteins. Using polymerase chain reaction-mediated DNA amplification from paraffin-embedded tissues and subsequent DNA sequence analysis, an activating point mutation was detected in the K-ras protooncogene in one tumor. This mutation was a G to A transition in position 2 of codon 12, substituting aspartate (GAT) for glycine (GGT). This type of mutation has not been observed before in human brain tumors, but it is frequent in radiation-induced murine lymphomas. These observations suggest that PNET can be induced after completion of the embryonal and fetal development of the human CNS. Oncogene-activating point mutations may represent a pathogenetic mechanism involved in the genesis of radiation-induced brain tumors.

Post radiation sarcoma (malignant fibrous histiocytoma) of the cervical spine following ependymoma (a case report)

A case is reported of a 36 y/o man treated with radiation therapy for cervical cord ependymoma who developed malignant fibrous histiocytoma of the cervical spine 15 years later. Pathology revealed the sarcoma adjacent to the recurrent ependymoma. Post-radiation sarcomas following treatment of central nervous system malignancies is discussed.

Second malignant neoplasms in patients treated for childhood leukemia. A population-based cohort study from the Nordic countries. The Nordic Society of Pediatric Oncology and Hematology (NOPHO)

Among a cohort of 981 children who were followed up 4.3-26.5 years after cessation of antileukemic therapy, eight patients in remission of acute lymphoblastic leukemia (ALL) developed a distinctively new malignant disease. The second malignant neoplasms (SMN) included brain tumors, basal cell carcinomas, thyroid cancer, leiomyosarcoma and finally rhabdomyosarcoma in a patient who also had suffered from Hodgkin's disease while still on antileukemic treatment. Cranial radiation had been given to 58.4% of the patients in the study group, which consisted of 895 ALL patients who had completed various chemotherapy protocols. With one exception, the SMN appeared after 7.5-16.5 years at a location previously exposed to radiotherapy (RT). The estimated cumulative risk of SMN appearing within 20 years after diagnosis was 2.9%, and the corresponding risk for cases with RT was 8.1% compared to 0.3% for those without (p = 0.05). In a Cox regression analysis, the incidence rate ratio of SMN between patients with and without RT was 6.7 (95% CI = 0.8, 57.7). Based on age-, year- and sex-specific cancer incidence figures for Norway, the overall standardized incidence rate ratio (SIR) of SMN after treatment for ALL was 5.9 (95% CI = 2.2, 12.9). The number of brain tumors among patients who had received cranial radiation was nearly 27 times greater than expected, whereas no such tumors were seen after chemotherapy. Individuals treated for childhood ALL are at increased risk of a new malignancy, and this seems mainly to be associated with previous irradiation.

Second intracranial neoplasms following treatment of childhood acute lymphoblastic leukaemia

We report a boy with acute lymphoblastic leukaemia (ALL) treated with chemotherapy and prophylactic cranial irradiation to a dose of 24 Gy. Six years after diagnosis he developed a glioma and died. Prior to 1979, four cases of second malignant neoplasm (SMN) of the brain had been reported in children treated for ALL. These SMNs occurred within 2 years of the original diagnosis (median 1.3 years) and at least two of four patients had not received prior radiotherapy. Since 1979, 28 cases of SMN of the brain have been reported including nine of 468 (1.9%) long-term survivors in one study. All occurred more than 3.7 years from diagnosis (median 6.5 years; range 4-13 years) and all received cranial irradiation (median 24 Gy; range 20-48 Gy). These data indicate a change in the pattern of SMNs which is most likely due to the introduction of cranial irradiation. As well, the frequency of SMNs in children treated for ALL appears to have increased, although it is still no greater than the risk of SMNs developing following the treatment of any other primary childhood neoplasm.

A report on radiation-induced gliomas

Radiation-induced gliomas are uncommon, with only 73 cases on record to date. The disease that most frequently occasioned radiation therapy has been acute lymphoblastic leukemia (ALL). Three more cases are added here, two after irradiation for ALL and one after irradiation for tinea capitis. In a review of the relevant literature, the authors stress the possibility that the ALL-glioma and the retinoblastoma-glioma links point to syndromes in their own right that may occur without radiation therapy.

The long-term side effects of radiation therapy for benign brain tumors in adults

Radiation therapy plays an integral part in managing intracranial tumors. While the risk:benefit ratio is considered acceptable for treating malignant tumors, risks of long-term complications of radiotherapy need thorough assessment in adults treated for benign tumors. Many previously reported delayed complications of radiotherapy can be attributed to inappropriate treatment or to the sensitivity of a developing child's brain to radiation. Medical records, radiological studies, autopsy findings, and follow-up information were reviewed for 58 adult patients (31 men and 27 women) treated between 1958 and 1987 with radiotherapy for benign intracranial tumors. Patient ages at the time of irradiation ranged from 21 to 87 years (mean 47.7 years). The pathology included 46 pituitary adenomas, five meningiomas, four glomus jugulare tumors, two pineal area tumors, and one craniopharyngioma. Average radiation dosage was 4984 cGy (range 3100 to 7012 cGy), given in an average of 27.2 fractions (range 15 to 45 fractions), over a period averaging 46.6 days. The follow-up period ranged from 3 to 31 years (mean 8.1 years). Findings related to tumor recurrence or surgery were excluded. Twenty-two patients had complications considered to be delayed side effects of radiotherapy. Two patients had visual deterioration developing 3 and 6 years after treatment; six had pituitary dysfunction; and 17 had varying degrees of parenchymal changes of the brain, occurring mostly in the temporal lobes and relating to the frequent presentation of pituitary tumors (two of these also had pituitary dysfunction). One clival tumor with the radiographic appearance of a meningioma, developed 30 years post-irradiation for acromegaly. This study unveils considerable delayed sequelae of radiotherapy in a series of adult patients receiving what is considered "safe" treatment for benign brain tumors.

CNS tumor induction by radiotherapy: a report of four new cases and estimate of dose required

We have analyzed 60 cases of intra-axial brain tumors associated with antecedent radiation therapy. These include four new cases. The patients had originally received radiation therapy for three reasons: (a) cranial irradiation for acute lymphoblastic leukemia (ALL), (b) definitive treatment of CNS neoplasia, and (c) treatment of benign disease (mostly cutaneous infections). The number of cases reported during the past decade has greatly increased as compared to previous years. Forty-six of the 60 intra-axial tumors have been reported since 1978. The relative risk of induction of an intra-axial brain tumor by radiation therapy is estimated to be more than 100, as compared to individuals who have not had head irradiation.

Malignant transformation of benign cerebellar astrocytoma

A patient who had a well-differentiated cerebellar astrocytoma resected at 4 years of age, had glioblastoma multiforme of the cerebellum after a symptom-free interval of 28 years. Late malignant transformation of a cerebellar astrocytoma of childhood is rare and previous cases are reviewed. Cerebellar astrocytomas are typically among the most benign of primary brain malignancies with excellent long-term survival rates, sometimes with incomplete resection. This patient indicates that follow-up needs to be long-term because biologic behavior cannot be predicted fully in all cases.

Glioblastoma multiforme of the cerebellum five decades after irradiation of a cerebellar tumor

A 70-year-old woman is reported who had glioblastoma multiforme of the cerebellum 52 years after radiation therapy to a midline cerebellar tumor. Seven similar reported cases are reviewed. Dedifferentiation of astrocytoma to glioblastoma and the role of radiation therapy are discussed.

Radiation-induced intracranial malignant gliomas

The authors present seven cases of malignant gliomas that occurred after radiation therapy administered for diseases different from the subsequent glial tumor. Included among these seven are three patients who were treated with interstitial brachytherapy. Previously reported cases of radiation-induced glioma are reviewed and analyzed for common characteristics. Children receiving central nervous system irradiation appear particularly susceptible to induction of malignant gliomas by radiation. Interstitial brachytherapy may be used successfully instead of external beam radiotherapy in previously irradiated, tumor-free brain, and thus may reduce the risk of radiation necrosis.

Neurogenic fibrosarcoma following radiation therapy for seminoma

We report a case of radiation-induced neurogenic fibrosarcoma that developed in a patient who received radiation therapy for seminoma. The sarcoma developed within the irradiated field after a latency period of nineteen years. Although the occurrence of a secondary neoplasm is unusual, this possibility should be included in the differential diagnosis of patients who present with tumor growth after a long interval following radiation therapy.

Postradiation astrocytoma. Report of two cases

The authors describe two cases of malignant astrocytomas associated with previous radiation therapy in childhood for intracranial germinoma and craniopharyngioma. In both patients, there was no recurrence at the primary tumor site. Because of a geometric coincidence between the tumor location and the radiation field, radiotherapy was strongly implicated as a cause of these two astrocytomas.

Late effects of antileukemic treatment

Increasing numbers of childhood ALL survivors have increased the need to assess the physical and psychosocial functioning of this group in a careful manner. This article reviews data on the frequency and types of second malignancies, structural and functional changes in the central nervous system, endocrine effects on growth and reproduction, and psychosocial aspects of development. Most long-term survivors of ALL do not have serious or life-threatening medical problems; however, medical and psychosocial problems may not be insignificant and may require coordinated management over prolonged periods.

Oligodendroglioma occurring after radiation therapy for pituitary adenoma

A 38 year old male dentist developed an oligodendroglioma of the left medial temporal lobe and parasellar region 12 years after radiotherapy with 6600 rads of acromegaly. The 30 cases of radiation-induced gliomas reported in the English literature are reviewed and analysed. The criteria for defining radiation-induced tumours of the central nervous system are proposed as follows: the tumour has a long quiescent "latency period", a location in the previously irradiated field, a verified histological difference from a primary condition, and does not arise from a primary condition associated with a genetic syndrome such as neurofibromatosis or tuberous sclerosis. The reported case fulfilled these criteria but appears to be the only reported radiation-induced oligodendroglioma.

Late multifocal gliomas in adolescents previously treated for acute lymphoblastic leukemia

Three of 37 adolescents in long-term remission from childhood acute lymphoblastic leukemia (ALL) developed malignant multifocal gliomas several years after completing treatment that included central nervous system (CNS) prophylaxis with radiation (RT) and intrathecal methotrexate (IT-MTX). No recurrence of the leukemia was evident when the CNS tumors were discovered. Seventeen other similar cases have been recorded. The occurrence of second malignancies is reviewed in the context of this development and of the oncogenic effects of radiation. It is probable that prolonged exposure to IT-MTX may have had a synergistic effect with radiation in contributing to the unusual incidence of glial tumors in these patients.

Brain tumors after cranial irradiation for childhood acute lymphoblastic leukemia. A 13-year experience from the Dana-Farber Cancer Institute and the Children's Hospital

Brain tumors developed in two children after they had received cranial irradiation as central nervous system therapy for acute lymphoblastic leukemia. A review of the literature demonstrated an increased incidence of brain tumors in survivors of acute lymphoblastic leukemia who received central nervous system irradiation. Most of the brain tumors occurred within a decade after radiotherapy. Further data will be required to determine whether early post-radiation brain tumors in patients with acute lymphoblastic leukemia are due to the central nervous system irradiation or to a genetic predisposition.

Postirradiation meningioma

A case of meningioma of the posterior cranial fossa is reported. The tumor developed 12 years after radiation treatment for a polar spongioblastoma of the cerebellum in an 8-year-old boy. The possible role of the radiation in the oncogenesis of the second tumor is discussed. In light of the information in the literature concerning the malignancy of such postirradiation tumors, the authors recommend careful evaluation for the real necessity of radiation therapy, particularly for children in whom the meninges may be hypersensitive to ionizing radiation.

The correlation of neoplastic vulnerability with central neuroepithelial cytogeny and glioma differentiation

The vulnerability of neuroepithelial cells in the central nervous system (CNS) to neoplastic transformation results from the interaction of several factors: the existence of a reserve population of stem cells, the capability of differentiated cells to reenter the kinetic cycle, the number of replicating cells at risk at a particular time, the length of time during which a particular cell population remains in the cycle, the state of differentiation and the further differentiation potential of that population, and the steps of differentiation that are achieved in successive cell generations. This concept explains many aspects of CNS tumor incidence and the relationship of central neuroepithelial embryonal tumors to tumors of adult cell type. The incidence of different types of central neuroepithelial tumors can be correlated with the width of the window of neoplastic vulnerability. Examples illustrating the existence of only a narrow window include such rare tumors as medulloepitheliomas, cerebral neuroblastomas, gangliogliomas and ependymoblastomas. By contrast, cerebellar medulloblastomas, astrocytomas, mixed astrocytomas and oligodendrogliomas, and glioblastomas exemplify instances in which a relatively wider window of vulnerability exists in the light of cellular neuro-ontogeny and of the capacity of glial cells for postnatal replication. The relationship that may occasionally be established between the development of a glioma and the production of cellular gliosis such as may follow brain injury or accompany multiple sclerosis can also be viewed in the light of that concept. Increasing awareness is needed concerning the development of postradiation gliomas, in particular after the apparently successful treatment of acute lymphocytic leukemia.

Cerebral astrocytoma as a complication of acute lymphoblastic leukaemia

A boy who developed acute lymphoblastic leukaemia at the age of two years and 10 months had several central nervous system relapses, and received two courses of cranial irradiation, each of 24 Gy, in addition to systemic and intrathecal chemotherapy. Nearly 10 years after the onset of his leukaemia he developed a brain stem astrocytoma from which he died. This appears to be a rare occurrence, and the role of the treatment in the induction of his second tumour is discussed. The need for the long-term follow-up of cancer patients after apparent cure is emphasized.