Medulloblastoma: the Duke University Medical Center experience

Hypothalamic-pituitary-gonadal function, pubertal development, and fertility outcomes in male and female medulloblastoma survivors: a single-center experience

BACKGROUND

Endocrine deficiencies, including hypothalamic-pituitary-gonadal axis (HPGA) impairment, are common in survivors of childhood and adolescent medulloblastoma. Still, data regarding pubertal development and fecundity are limited, and few studies assessed HPGA function in males. We aimed to describe HPGA function in a large cohort of patients with medulloblastoma.

METHODS

A retrospective study comprising all 62 medulloblastoma patients treated in our center between 1987 and 2021, who were at least 2 years from completion of therapy. HPGA function was assessed based on clinical data, biochemical markers, and questionnaires.

RESULTS

Overall, 76% of female patients had clinical or biochemical evidence of HPGA dysfunction. Biochemical evidence of diminished ovarian reserve was seen in all prepubertal girls (n = 4). Among the males, 34% had clinical or biochemical evidence of gonadal dysfunction, 34% had normal function, and 29% were age-appropriately clinically and biochemically prepubertal. The difference between males and females was significant (P = .003). Cyclophosphamide-equivalent dose was significantly associated with HPGA function in females, but not in males. There was no association between HPGA dysfunction and other endocrine deficiencies, length of follow-up, weight status, and radiation treatment protocol. Two female and 2 male patients achieved successful pregnancies, resulting in 6 live births.

CONCLUSIONS

HPGA dysfunction is common after treatment for childhood medulloblastoma. This is seen more in females, likely due to damage to the ovaries from spinal radiotherapy. Our findings may assist in counseling patients and their families regarding risk to future fertility and need for fertility preservation.

Worldwide Trends in Survival From Common Childhood Brain Tumors: A Systematic Review

PURPOSE

The histology of brain tumors determines treatment and predicts outcome. Population-based survival reflects the effectiveness of a health care system in managing cancer. No systematic review of worldwide variation and time trends in survival from brain tumors in children is currently available.

PATIENTS AND METHODS

We considered longitudinal, observational studies comprising children diagnosed with intracranial astrocytic or embryonal tumors. We searched six electronic databases from database inception to September 30, 2018, using complex search strategies. The outcome measure was 5-year survival, estimated through a time-to-event analysis. This study is registered with PROSPERO, number CRD42018111981.

RESULTS

Among 5,244 studies, we identified 47 eligible articles that provided 228 survival estimates. Only five studies were entirely or partially conducted in low-income or middle-income countries. Five-year survival from embryonal tumors increased from 37% in 1980 to approximately 60% in 2009. Although survival for medulloblastoma improved substantially (from 29% to 73% during 1959-2009), survival for primitive neuroectodermal tumors wavered over time (1973-2009) and between countries. Five-year survival from astrocytoma changed very little over the 27 years between 1982 and 2009 (from 78% to 89%). Interpretation of the literature was made difficult by the heterogeneity of study designs.

CONCLUSION

Survival has improved for embryonal tumors, but little change has been observed for astrocytic tumors. We found a striking gap in knowledge about survival from childhood brain tumor subtypes in middle-income and low-income countries, where half of these tumors are diagnosed. Larger studies are needed, including in under-represented countries and based on standardized data collection, to provide up-to-date survival estimates.

Potential use of CXCL12/CXCR4 and sonic hedgehog pathways as therapeutic targets in medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor occurring in children, and although high long-term survival rates have been reached with current therapeutic protocols, several neurological injuries are still observed among survivors. It has been shown that the development of MB is highly dependent on the microenvironment surrounding it and that the CXCL12 chemokine and its receptor, CXCR4 and the Sonic Hedgehog (SHH) pathway are crucial for cerebellar development, coordinating proliferation and migration of embryonic cells and malfunctions in these axes can lead to MB development. Indeed, the concomitant overactivation of these axes was suggested to define a new MB molecular subgroup. New molecules are being studied, aiming to inhibit either CXCR4 or the SHH pathways and have been tested in preclinical settings for the treatment of cancers. The use of these molecules could improve MB treatment and save patients from aggressive surgery, chemotherapy and radiotherapy regimens, which are responsible for severe neurological consequences. This review aims to summarize current data about the experimental inhibition of CXCR4 and SHH pathways in MB and its potential implications in treatment of this cancer.

PI3K pathway regulates survival of cancer stem cells residing in the perivascular niche following radiation in medulloblastoma in vivo

Medulloblastomas are brain tumors that arise in the cerebellum of children and contain stem cells in a perivascular niche thought to give rise to recurrence following radiation. We used several mouse models of medulloblastomas in parallel to better understand how the critical cell types in these tumors respond to therapy. In our models, the proliferating cells in the tumor bulk undergo radiation-induced, p53-dependent apoptotic cell death. Activation of Akt signaling via PTEN loss transforms these cells to a nonproliferating extensive nodularity morphology. By contrast, the nestin-expressing perivascular stem cells survive radiation, activate PI3K/Akt pathway, undergo p53-dependent cell cycle arrest, and re-enter the cell cycle at 72 h. Furthermore, the ability of these cells to induce p53 is dependent on the presence of PTEN. These cellular characteristics are similar to human medulloblastomas. Finally, inhibition of Akt signaling sensitizes cells in the perivascular region to radiation-induced apoptosis.

Late Relapse of Pediatric Medulloblastoma

Medulloblastoma ( MB), the most common malignant brain tumor of childhood, is classified according to pathomorphologic characteristics in the group of central nervous system embryonal tumors, but both its pathogenesis and biologic behavior remain unknown. In addition, the relationship of MB to other embryonal brain tumors is debated and response to therapy is difficult to predict. The authors report an uncommon case of unfavorable late relapse, local as well as distant, in a 26-year old male patient, who was free of disease and without treatment-related morbidity for fifteen years after combined therapy for pediatric MB.

Collins' law revisited: can we reliably predict the time to recurrence in common pediatric tumors?

Collins' law states that the period of risk for tumor recurrence is the age of the child at diagnosis plus 9 months. The purpose of this study is to validate this rule through a retrospective review of common pediatric tumors seen at 1 institution. Inclusion criteria for this study included an age at diagnosis of < 16 years old, minimum follow-up time of the Collins risk period (CRP) if child did not relapse and treatment with curative intent. The records of 424 children seen and treated for neuroblastoma (n = 98), Wilms tumor (n = 86), rhabdomyosarcoma (n = 82), medulloblastoma (n = 59), Ewing sarcoma (n = 43), ependymoma (n = 25), supratentorial PNET (n = 22), and synovial sarcoma (n = 9) from 1960 to 2001 were reviewed. CRP was calculated using the age of child at initial diagnosis plus 9 months. The median follow-up time was 164 months (range, 11-484 months), while the median follow-up/CRP ratio was 4.89 (range, 1.0-48.0). A total of 183 of 424 (43.2%) patients relapsed, with 180 (98.4%) relapses occurring during the CRP. Relapses beyond the CRP were seen in 3 young children (ages 7 months, 24 months, and 2 weeks at initial diagnosis) with a diagnosis of Wilms tumor (n = 2) and supratentorial PNET (n = 1) at 1, 3, and 26 months post-CRP. Collins' law is a useful and simple way of predicting risk period for relapse in the tumor types studied.

Neurosurgical treatment of brain tumors in children

Primary brain tumors are the most common solid neoplasms of childhood. The diagnosis of brain tumors in the general pediatric population remains challenging. Nevertheless, it is clear that refinements in imaging, surgical technique, and adjunctive therapies have led to longer survival and an improving quality of life in children with brain tumors.

Medulloblastoma in childhood: Impact of radiation technique upon the outcome of treatment

BACKGROUND

Medulloblastoma is an infratentorial primitive neuroectodermal tumour, diagnosed in paediatric population. The radiotherapy is an essential method of treatment for these tumours. The impact of technical quality of radiation therapy on survival was recently considered. In this study treatment-related variables are analysed with a special focus on radiotherapy technical factors.

PROCEDURE

The population of 158 children with a diagnosis of medulloblastoma had been undergoing postoperative radiotherapy at MCMCC in Warsaw in the period 1983-1997. The medical data of these patients were analysed. Simulation films of the whole-brain irradiation fields were retrospectively reviewed at 112 patients. The distance from the field margin to the cribriform plate and to the floor of the temporal fossa was assessed and correlated with supratentorial relapse.

RESULTS

Five-year overall survival (OS) and 5-year disease free survival (DFS) were 46% and 40%, respectively. In multivariate analysis gender (P = 0.008), neurological status before radiotherapy (P = 0.029), M-stage (P < 0.001) and sequence of craniospinal irradiation (P = 0.019) were significant prognostic factors for OS. For DFS significant factors were M-stage (P < 0.001) and neurological status (P < 0.001). The cranial fields were not fully correctly covered at 43% patients. The field incorrectness was correlated with isolated supratentorial failure (P = 0.049).

CONCLUSIONS

Our results are similar to those published in literature. M0-stage was the most powerful favourable prognostic factor. Male gender and neurological status before radiation treatment were associated with poor survival. Also protracted radiotherapy and quality of radiation technique may have an impact on the outcome.

Familial medulloblastoma: case report of one family and review of the literature

OBJECTIVE AND IMPORTANCE

Medulloblastoma is the most common malignant brain tumor and the most common malignant solid tumor in children. Most medulloblastomas are sporadic, but rare familial forms have been described. To the best of our knowledge, only 10 case reports of familial medulloblastoma have been published. A variety of candidate genes have been suggested to be involved in familial medulloblastomas. However, the exact pathogenesis and genetics involved in familial medulloblastoma remain unknown.

CLINICAL PRESENTATION

We describe the presentation of medulloblastoma in two siblings (one of each sex) and their great-uncle. The three cases differ with regard to age at onset and pathological subtype of medulloblastoma. INTERVENTION OR TECHNIQUE: Immunostaining of tissue blocks for gene products involved in medulloblastoma differed in the two siblings for beta-catenin and was similar with staining for gli.

CONCLUSION

This article is only the second report in the literature to address the genetics of familial medulloblastoma in the absence of characterized conditions such as Li-Fraumeni's cancer syndrome and basal cell nevus, Rubinstein-Taybi's, and Turcot's syndromes. The discrepancy in beta-catenin staining in the two siblings suggests that the two tumors differentiated through divergent pathways. We briefly summarize all published cases of familial medulloblastoma and review the literature on the genes involved in medulloblastoma formation.

Intensity-modulated radiation therapy for pediatric medulloblastoma: early report on the reduction of ototoxicity

PURPOSE

The combination of cisplatin chemotherapy and radiation therapy for the treatment of medulloblastoma has been shown to cause significant ototoxicity, impairing a child's cognitive function and quality of life. Our purpose is to determine whether the new conformal technique of intensity-modulated radiation therapy (IMRT) can achieve lower rates of hearing loss by decreasing the radiation dose delivered to the cochlea and eighth cranial nerve (auditory apparatus).

PATIENTS AND METHODS

Twenty-six pediatric patients treated for medulloblastoma were retrospectively divided into two groups that received either conventional radiotherapy (Conventional-RT Group) or IMRT (IMRT Group). One hundred thirteen pure-tone audiograms were evaluated retrospectively, and hearing function was graded on a scale of 0 to 4 according to the Pediatric Oncology Group's toxicity criteria. Statistical analysis comparing the rates of ototoxicity was performed using Fisher's exact test with two-tailed analysis.

RESULTS

When compared to conventional radiotherapy, IMRT delivered 68% of the radiation dose to the auditory apparatus (mean dose: 36.7 vs. 54.2 Gy). Audiometric evaluation showed that mean decibel hearing thresholds of the IMRT Group were lower at every frequency compared to those of the Conventional-RT Group, despite having higher cumulative doses of cisplatin. The overall incidence of ototoxicity was lower in the IMRT Group. Thirteen percent of the IMRT Group had Grade 3 or 4 hearing loss, compared to 64% of the Conventional-RT Group (p < 0.014).

CONCLUSION

The conformal technique of IMRT delivered much lower doses of radiation to the auditory apparatus, while still delivering full doses to the desired target volume. Our findings suggest that, despite higher doses of cisplatin, and despite radiotherapy before cisplatin therapy, treatment with IMRT can achieve a lower rate of hearing loss.

Impact of targeting deviations on outcome in medulloblastoma: study of the French Society of Pediatric Oncology (SFOP)

PURPOSE

To correlate targeting deviation in external beam radiation therapy with site of relapse in a prospective study of 174 patients treated for medulloblastoma.

METHODS AND MATERIALS

Between February 1992 and February 1998 the radiotherapy treatment records were reviewed by a panel of radiation oncologists for 174 children treated with radiation therapy for medulloblastoma. The review was done without knowledge of patient outcome. Patterns of relapse were correlated with the results of the quality control review.

RESULTS

Among the 174 patients five relapsed before the start of radiotherapy. One hundred sixty-nine patients were evaluable for correlation between targeting deviation and site of relapse. Number of major deviations in radiation therapy treatment is strongly correlated with the risk of tumor relapse (67% [95% CI: 28-91] of 3-year relapse rate in patient group with 2 major deviations and 78% [95% CI: 35-96] with 3 major deviations). This is particularly correlated with relapse in the frontal region of the brain: 5 relapses occurred in the frontal region in patients with major deviation in this area. An erroneous choice of electron beam energy is also linked with craniospinal fluid (CSF) relapse (3-year relapse rate of 68% [95% CI: 42-86]). Minor deviations in therapy technique are slightly associated with an increased risk of relapse in the same range as the group with only one major deviation.

CONCLUSION

The quality of medulloblastoma radiation therapy technique is strongly correlated with outcome. Pretreatment central quality assurance review or standardized computer-designed blocks would improve survival to an extent equivalent to that attributed to adjuvant chemotherapy.

Medulloblastoma and supratentorial primitive neuroectodermal tumors: an institutional experience

BACKGROUND

To the authors' knowledge there are relatively few data concerning supratentorial primitive neuroectodermal tumors (PNET). The authors retrospectively reviewed all cases of PNET of the brain treated at the study institution to determine whether there was a difference in presentation, overall survival, and recurrence-free survival with regard to tumor location (supratentorium vs. posterior fossa).

METHODS

Between 1977-1996 33 patients with PNET were diagnosed and treated at 1 radiotherapy center. The median age of the patients was 9 years. The location of the tumor was in the posterior fossa in 25 patients and the supratentorium in 8 patients. The tumor had spread to the neuraxis in six patients; four patients with disseminated neuraxis disease had a supratentorial PNET and two had a posterior fossa PNET. All but three patients received craniospinal irradiation. The primary tumor received > or = 5000 centigray in 27 patients and chemotherapy was employed in 26 patients. The median follow-up was 60 months.

RESULTS

The 5-year overall and recurrence-free survival rates for all patients were 77.2% and 79.6%, respectively. The 5-year overall survival rates were 86.3% for patients with medulloblastoma (posterior fossa PNET) and 46.9% for patients with supratentorial PNET (P = 0.01, log rank test). For overall survival, prognostic factors included radiotherapy dose to the primary site, metastases (M) status, and location of the primary tumor. The 5-year recurrence free survival rates were 89.8% for patients with medulloblastoma and 46.9% for patients with supratentorial PNET (P = 0.003, log rank test). For recurrence free survival, prognostic factors included M status and primary tumor site location; radiation dose to the primary tumor site and patient gender were of borderline significance. In the ten patients with inadequate posterior fossa boost fields judged by Children's Cancer Group criteria, there were two failures, both of which were in the original tumor bed.

CONCLUSIONS

Supratentorial PNET has a worse overall survival and recurrence free survival than medulloblastoma. There is a suggestion that radiotherapy boosts in medulloblastoma may not need to encompass the entire posterior fossa because posterior fossa failures primarily are in the tumor bed. Larger studies with longer follow-up are needed to determine whether craniospinal irradiation followed by a boost to the tumor bed is adequate for medulloblastoma patients.

Metastasis stage, adjuvant treatment, and residual tumor are prognostic factors for medulloblastoma in children: conclusions from the Children's Cancer Group 921 randomized phase III study

PURPOSE

From 1986 to 1992, "eight-drugs-in-one-day" (8-in-1) chemotherapy both before and after radiation therapy (XRT) (54 Gy tumor/36 Gy neuraxis) was compared with vincristine, lomustine (CCNU), and prednisone (VCP) after XRT in children with untreated, high-stage medulloblastoma (MB).

PATIENTS AND METHODS

Two hundred three eligible patients with an institutional diagnosis of MB were stratified by local invasion and metastatic stage (Chang T/M) and randomized to therapy. Median time at risk from study entry was 7.0 years.

RESULTS

Survival and progression-free survival (PFS) +/- SE at 7 years were 55%+/-5% and 54%+/-5%, respectively. VCP was superior to 8-in-1 chemotherapy, with 5-year PFS rates of 63%+/-5% versus 45%+/-5%, respectively (P = .006). Upon central neuropathology review, 188 patients were confirmed as having MB and were the subjects for analyses of prognostic factors. Children aged 1.5 to younger than 3 years had inferior 5-year estimates of PFS, compared with children 3 years old or older (P = .0014; 32%+/-10% v 58%+/-4%, respectively). For MB patients 3 years of age or older, the prognostic effect of tumor spread (MO v M1 v M2+) on PFS was powerful (P = .0006); 5-year PFS rates were 70%+/-5%, 57%+/-10%, and 40%+/-8%, respectively. PFS distributions at 5 years for patients with M0 tumors with less than 1.5 cm2 of residual tumor, versus > or = 1.5 cm2 of residual tumor by scan, were significantly different (P = .023; 78%+/-6% v 54%+/-11%, respectively).

CONCLUSION

VCP plus XRT is a superior adjuvant combination compared with 8-in-1 chemotherapy plus XRT. For patients with M0 tumors, residual tumor bulk (not extent of resection) is a predictor for PFS. Patients with M0 tumors, > or = 3 years with < or = 1.5 cm2 residual tumor, had a 78%+/-6% 5-year PFS rate. Children younger than 3 years old who received a reduced XRT dosage had the lowest survival rate.

Brain tumor survival: results from the National Cancer Data Base

Hospital-based data reported to the National Cancer Data Base (NCDB) were available for over 60,000 patients with a primary brain tumor diagnosed from 1985-1988 and 1990-1992. The most common histologies were glioblastomas, astrocytomas and meningiomas. Five-year survival rates for these tumors were 2%, 30% and 70% respectively. Histology, age at diagnosis, behavior, and location were important variables in estimating survival. Comparisons with population-based registry data suggest that the malignant tumors are well represented in NCDB, but the benign histologies are under-reported. Survival estimates for the malignant tumors are comparable to previously reported studies. The NCDB provides recent information on brain tumor distribution and survival patterns not available in other large databases.

Internalization with high targeting potential of mouse monoclonal antibody ONS-M21 recognizing human malignant glioma antigen

In order to evaluate the targeting potential of mouse monoclonal antibody ONS-M21 recognizing a human astrocytoma- and medulloblastoma-associated antigen, the internalization ability of this antibody and the selective cytotoxicity in the toxin-conjugated form were examined. Internalization assay with 125I-labeled ONS-M21 showed that about 20% of the total radioactivities was detected in the cellular fraction of human medulloblastoma cell line ONS-76 cells and that the reaction reached a plateau level in 30 min. To examine the selective delivery capacity of a high molecular substance in place of 125I, an immunotoxin was prepared with ricin A chain and ONS-M21 via disulfide bonds. A cytotoxic effect against ONS-76 cells was found with [3H]thymidine incorporation assay using the immunotoxin, but not against antigen-negative HuH-7 and SW480 cells. These results suggest that ONS-M21 could effectively deliver toxins, chemotherapeutic agents or radionuclei to malignant glioma specifically.

Medulloblastoma: survival and late recurrence after the Collins' risk period

Sixty-three patients with cerebellar medulloblastoma were treated between 1963 and 1992 at our institution. Among them, 10 patients have survived beyond the Collins' risk period. These included 6 males and 4 females who ranged in age from 6 months to 12 years at the time of diagnosis. A total removal of the tumor was achieved in 4 patients, while there was a subtotal removal in 3, and a partial removal in 3. Histologically, 6 tumors were classified as a classical type of medulloblastoma, and 4 were diagnosed as being a desmoplastic type. Postoperatively, 9 patients received craniospinal radiation therapy, and one received local radiation to the primary site. During the follow-up period of 3.9-25.4 years, 5 patients have been in continuous remission for from 14.2 to 25.4 years and are leading normal lives, 2 have survived for 18.1 and 18.5 years with mild to moderate neurological deficits, while the remaining 3 died after the Collins' risk period. Two out of these last 3 patients were under the age of one year at the time of onset, while the remaining one died after a second recurrence. We conclude that careful follow-up is needed for all long-term survivors even after the Collins' risk period, especially for those who were under the age of 1 year at onset and who failed in the initial treatments.

Survival rates in patients with primary malignant brain tumors stratified by patient age and tumor histological type: an analysis based on Surveillance, Epidemiology, and End Results (SEER) data, 1973-1991

OBJECT

The authors present population-based survival rate estimates for patients with malignant primary brain tumors based on an analysis of 18 years of data obtained from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute.

METHODS

Estimates of survival rates at 2 and 5 years after diagnosis for patients with specific histological tumor types were categorized by patient's age at diagnosis (< or = 20 years, 21-64 years, and 65 years or older) and by the time period in which the patients were diagnosed (1973-1980, 1981-1985, 1986-1991). Where appropriate, survival estimates were adjusted for changing patterns in the mean age at diagnosis.

CONCLUSIONS

The authors observed a pattern of declining survival rates in patients with increasing age of the patient at diagnosis for most histological groups and overall improvements in survival rates of patients across these time periods adjusting for age at diagnosis. There were improvements in 2- and 5-year survival rates over the three time periods for children and adults with medulloblastoma and for adults with astrocytoma and oligodendroglioma. Improvements in survival rates for pediatric patients with medulloblastoma have leveled off in the most recent time period, and gender differences in survival rates for patients with this tumor, which were present in the 1970s, have disappeared. Clinically significant improvements in survival rates were not apparent in patients aged 65 years and older. Changes in diagnostic and treatment procedures since the mid-1970s have resulted in improved survival rates for patients diagnosed as having medulloblastoma, oligodendroglioma, and astrocytoma, controlling for age at diagnosis. Glioblastoma multiforme continues to be the most intractable brain tumor.

Is medulloblastoma the same tumor in children and adults?

The appearance of medulloblastoma in adult age and the uncertain overlapping of prognostic factors in pediatric and adult populations stimulate the question of whether medulloblastoma is different in adults and in children. The pathologic features, proliferation potential and glial/neuronal differentiation have been investigated in 42 adult medulloblastomas and 42 medulloblastomas of children; the quantitative data have been compared between the two groups of age. Homer-Wright rosettes, nuclear polymorphism and histologic signs of neuronal differentiation were more frequent in children cases; GFAP-positive tumor cells and desmoplastic type were more frequent in adult cases. The mean, median and rage of Lis, with PCNA and MIB-1 were significantly (p < 0.05) higher in adults than in children. All cases, independently from age of the patients were immunoreactive with markers of neuronal commitment (class III beta tubulin isotype, MAP-2, neurofilaments). The immunoreactivity pattern suggested a more mature neuronal character in desmoplastic cases of adults than of children and in classic cases of children than of adults. In conclusion, some phenotypic differences between childhood and adult medulloblastoma exist, but do not support a substantially different course of the disease. The higher proliferation potential in adult than in childhood cases is unexpected in a tumor of embryonal origin, and reduces the applicability of Collin's law to medulloblastoma.

Potential role of proton therapy in the treatment of pediatric medulloblastoma/primitive neuroectodermal tumors: reduction of the supratentorial target volume

PURPOSE

One of the components of radiotherapy (RT) in medulloblastoma/primitive neuroectodermal tumors is the prophylactic irradiation of the whole brain (WBI). With the aim of reducing late neuropsychologic morbidity a CT-scan-based dosimetric study was undertaken in which treatment was confined mainly or exclusively to supratentorial sites considered at high risk for disease recurrence.

METHODS AND MATERIALS

A comparative dosimetric study is presented in which a three field (two laterals and one posterior) proton plan (spot scanning method) is compared with a two-field conventional WBI 6 MV x-ray plan, to a 6-field "hand-made" 6 MV x-ray plan, and to a computer-optimized 9-field "inverse" 15 MV x-ray plan. For favorable patients, 30 Gy were delivered to the ventricles and main cisterns, the subfrontal and subtemporal regions, and the posterior fossa. For the unfavorable patients, 10 Gy WBI preceeded a boost to 30 Gy to the same treatment volume chosen for favorable patients. The dose distribution was evaluated with dose-volume histograms to examine the coverage of the targets as well as the dose to the nontarget brain and optical structures. In addition, the risks of radiation-related late neuropsychologic effects after WBI were collected from the literature and used to predict normal tissue complication probabilities (NTCPs) for an intelligence quotient deficit after treatment with photon or proton beams.

RESULTS

Proton beams succeeded better in reducing the dose to the brain hemispheres and eye than any of the photon plans. A 25.1% risk of an IQ score <90 was predicted after 30 Gy WBI. Almost a 10% drop in the predicted risk was observed when using proton beams in both favorable and unfavorable patients. However, predicted NTCPs for both optimized photon plans ("hand made" and "inverse") were only slightly higher (0.3-2.5%) than those of proton beams. An age-modifying factor was introduced in the predictive NTCP model to assess for IQ differences in relation with age at irradiation. Children with ages between age 4 to 8 benefitted most from the dose reduction in this exercise (similar NTCP predictions for both proton and "inverse" plans).

CONCLUSION

Modulated proton beams may help to significantly reduce the irradiation of normal brain while optimally treating the supratentorial subsites at higher risk for relapse. A decrease in morbidity can be expected from protons and both optimized proton plans compared to WBI.

Primitive neuroectodermal tumors of the central nervous system

Controversial issues relating to the pathobiology and classification of central nervous system primitive neuroectodermal tumors (PNETs) have plagued neuropathologists for more than 70 years. Hypotheses advanced in the mid-1920's have remained as fixed concepts in contemporary literature, largely consequent to repetitious support by a small number of neuropathologists despite a growing body of information discrediting these ideas from neuroembryologists, oncologists, neuroscientists and pathologists. Attention has largely focused upon PNETs arising in the cerebellum (commonly known as medulloblastomas ([MBs]), because about 80% of central nervous system (CNS) PNETs originate in this site. It has been asserted that the 20% which do not are biologically different, although most individuals agree that the histological features of PNETs that occur in different sites throughout the CNS are indistinguishable from those growing in the cerebellum. The historical aspects of this controversy are examined in the face of evidence that there is, in fact, a unique class of CNS tumors which should appropriately be regarded as primitive neuroectodermal in nature. Specifically, a number of different approaches to the problem have yielded data supporting this hypothesis. These approaches include the identification of patterns of expression among a variety of cellular antigens (demonstrated by the use of immunopathological techniques), molecular analyses of cell lines derived from these tumors, experimental production of PNETs and molecular genetic analyses. Differences of opinion among surgeons, oncologists and radiotherapists are typically resolved by conducting cooperative studies of patients with these tumors who are diagnosed and treated at multiple centers.

Pediatric medulloblastoma: radiation treatment technique and patterns of failure

PURPOSE

In this study factors are analyzed that may potentially influence the site of failure in pediatric medulloblastoma. Patient-related, disease-related, and treatment-related variables are analyzed with a special focus on radiotherapy time-dose and technical factors.

METHODS AND MATERIALS

Eighty-six children and adolescents with a diagnosis of medulloblastoma were treated in Switzerland during the period 1972-1991. Postoperative megavoltage radiotherapy was delivered to all patients. Simulation and portal films of the whole-brain irradiation (WBI) fields were retrospectively reviewed in 77 patients. The distance from the field margin to the cribiform plate and to the floor of the temporal fossa was carefully assessed and correlated with supratentorial failure-free survival. In 19 children the spine was treated with high-energy electron beams, the remainder with megavoltage photons. Simulation and port films of the posterior fossa fields were also reviewed in 72 patients. The field size and the field limits were evaluated and correlated with posterior fossa failure-free survival.

RESULTS

In 36 patients (47%) the WBI margins were judged to miss the inferior portion of the frontal and temporal lobes. Twelve patients failed in the supratentorial region and 9 of these patients belonged to the group of 36 children in whom the inferior portion of the brain had been underdosed. On multivariate analysis only field correctness was retained as being significantly correlated with supratentorial failure-free survival (p = 0.049). Neither the total dose to the spinal theca nor the treatment technique (electron vs. photon beams) were significantly correlated with outcome. Posterior fossa failure-free survival was not influenced by total dose, overall treatment time, field size, or field margin correctness. Overall survival was not influenced by any of the radiotherapy-related technical factors.

CONCLUSION

A correlation between WBI field correctness and supratentorial failure-free survival was observed. Treatment protocols should be considered that limit supratentorial irradiation mainly to subsites at highest risk of relapse. Optimized conformal therapy or proton beam therapy may help to reach this goal. Treating the spine with electron beams was not deletereous. A significant correlation between local control and other technical factors was not observed, including those relating to posterior fossa treatment. The use of small conformal tumor bed boost fields may be prefered to the larger posterior fossa fields usually considered as the standard treatment approach.

[Medulloblastoma in adults. Val-de-Grace hospital experience (1975-1994) and literature review]

PURPOSE

Retrospective analysis of prognostic factors in a series of 14 adult patients presenting with medulloblastoma treated by surgery and subsequent radiotherapy.

PATIENTS AND METHODS

Thirteen male and one female patients (mean age, 27 years; range 20-40) presenting with medulloblastoma were treated at the Val-de-Grâce hospital from 1975 to 1994. The mean delay between the initial symptoms and the diagnosis was 17 weeks (range, 2-76). The tumor was median in three cases, lateral in seven, and median and lateral in four. Eleven medulloblastomas belonged to the classical subtype and three others to the desmoplastic type. Patients were treated by surgery followed by external radiation therapy. The ablation was complete in four cases and incomplete in ten cases.

RESULTS AND CONCLUSION

Five- and ten-year overall survival rates were 63 and 25%, respectively. There was a trend toward a higher probability of survival for older patients (ie, for patients above 26 years of age) presenting with a desmoplastic central tumor treated by complete surgery and subsequent post-operative radiotherapy. Results are discussed in regard to the literature.

Is there a correlation between duration of presenting symptoms and stage of medulloblastoma at the time of diagnosis?

BACKGROUND

Does a "delay in diagnosis" lead to a child being diagnosed with advanced stage as opposed to early stage medulloblastoma? Correlation between the duration of a patient's presenting symptoms and stage at diagnosis was examined.

METHODS

The population consisted of 72 consecutive patients with histologically proven medulloblastoma diagnosed between July 1, 1983 and July 31, 1995. A standard history and physical examination format was used to record the nature and duration of presenting symptoms. Patients were staged by use of the operative findings, pre- and postoperative cranial computed tomography (CT) scans and, later in the series, cranial magnetic resonance imaging (MRI) studies and, for determination of the M stage, myelography, spinal MRI, and postoperative cerebrospinal fluid cytology.

RESULTS

There were 40 males (56%) and 32 females (44%) with a mean age of 11.8 years. The most common presenting symptoms were vomiting (67%), headache (60%), ataxia (40%), and nausea (39%). By the Chang-Harisiadis (CH) system, 39 patients (54%) were found to have high stage medulloblastoma (T3b-4M0 or any TM1-4), 27 (38%) had low stage disease (T1-3aM0), and in 6 (8%) the stage could not be fully determined. By the Langston modification of the Change-Harisiadis system (LCH) 38 patients (54%) had high stage, 24 (32%) had low stage, and in 10 (14%) the stage could not be fully determined. Fifty of the 66 patients for whom the duration of symptoms was known (76%) had < or = 3 months of symptoms prior to stage. High CH stage patients had a mean duration of symptoms of 7.4 +/- 6.9 weeks versus 19.5 +/- 22.5 weeks for low stage patients. (P < 0.001). High LCH stage patients had a mean duration of symptoms of 7 +/- 6.6 weeks versus 15.4 +/- 16.4 weeks for low stage patients (P < 0.01). Patients ultimately found to have MO disease were diagnosed more slowly (16.1 +/- 20 weeks) than those with M1 (7.3 +/- 5.3 weeks), M2 (6 +/- 5.3 weeks), or M3 disease (6.8 +/- 5.9 weeks) M0 vs. M1-3, P < 0.02). No patients had M4 disease. Using an alternative definition of high versus low stage (T4M0 or any TM1-4 vs. T1-3bM0) currently under consideration by pediatric oncologists, the duration of symptoms remained significantly longer for low stage disease in the CH system (high vs. low, 7.2 +/- 5.8 weeks vs. 17.5 +/- 19.1 weeks, P < 0.01) but not in the LH system (high vs. low, 10.6 +/- 16.1 weeks vs. 13.9 +/- 15.9 weeks, P not significant).

CONCLUSIONS

A short duration of symptoms is associated with the diagnosis of more advanced medulloblastoma. This finding has significant potential implications for the identification of prognostic groups in medulloblastoma as well as medical-legal claims of "delay in diagnosis" and capitated health care issues.

Medulloblastoma: long-term results for patients treated with definitive radiation therapy during the computed tomography era

PURPOSE

We performed a retrospective evaluation of the patterns of failure and outcome for medulloblastoma patients treated with craniospinal irradiation therapy during the computed tomography (CT) era.

MATERIALS AND METHODS

The records of 100 patients treated at Memorial Sloan-Kettering Cancer Center between 1979 and 1994 were reviewed. CT scans or magnetic resonance imaging were used to guide surgical intervention and evaluate the extent of resection postoperatively. All patients were treated with conventional fractionation (1.8 Gy/day) and the majority received full-dose neuraxis radiation therapy and > 50 Gy to the primary site.

RESULTS

With a median follow-up of 100 months, the median, 5-year, and 10-year actuarial overall survival for the entire group were 58 months, 50%, and 25%, respectively. The median, 5- and 10-year actuarial disease-free survivals were 37 months, 41%, and 27%, respectively. Patients with localized disease (no evidence of disease beyond the primary site) had significantly improved overall (p < 0.02) and disease-free (p < 0.02) survivals compared to those with nonlocalized disease. For patients with localized disease, the 5- and 10-year overall survival rates were 59% and 31%, whereas the disease-free survivals were 49% and 31%, respectively. Disease-free and overall survivals at similar intervals for patients with nonlocalized disease were 29% and 30% (5 years), and 29% and 20% (10 years), respectively. Sixty-four of 100 patients failed treatment. Local failure as any component of first failure occurred in 35% of patients or 55% (35 of 64) of all failures and as the only site of first failure in 14% or 22% (14 of 64) of all failures. For patients presenting with localized disease (n = 68), local failure as any component of first failure occurred in 32% (22 of 68) and in 18% (12 of 68) as the only site. A multivariate analysis showed that M stage was the only prognostic factor to influence overall survival. For disease-free survival, M stage and the extent of resection were prognostic factors. Ventriculoperitoneal shunting and the use of chemotherapy were associated with a poor outcome; however, these results were confounded by the positive impact of chemotherapy in decreasing the risk of extraneural metastases and the use of these therapies in the more advanced patients.

CONCLUSION

These long-term follow-up data represent one of the largest series of patients with complete follow-up who were treated with a consistent radiation therapy treatment policy during the CT era. Local failure in patients with localized disease, the persistent risk of late failures, treatment-related toxicity, and the ever-present risk of secondary malignancies demonstrate the limitations of standard therapies. Strategies used to increase the total dose to the primary site should be pursued along with other adjuvant therapies such as intensive chemotherapy.

Impact of radiation technique upon the outcome of treatment for medulloblastoma

Craniospinal irradiation (CSI) is an essential component of the therapy of medulloblastoma. Because medulloblastoma disseminates via the cerebrospinal fluid (CSF), CSI technique involves the irradiation of all CSF-bearing areas which are at risk for tumor seeding. Underdosing with radiation because of inadequacies in CSI technique will produce dose "cold spots" which have the potential of serving as a nidus for tumor recurrence. A simple mathematic model of subclinical disease in medulloblastoma based on the available data concerning the radiosensitivity of medulloblastoma cell lines as well as the known clinical dose-response relationships support the hypothesis that for most cases of medulloblastoma, the radiotherapist is working in a range of doses arrayed on the steep portion of the tumor control probability curve. Underdosing of CSF-bearing areas because of technical problems at the junction of the cranial and spinal fields of irradiation, placement of shielding blocks in the cribiform plate-subfrontal region, and/or anatomic errors in the design of the caudal end of the CSI fields may lead to significant risks of tumor relapse. One may debate the necessity of a posterior fossa boost encompassing the entire anatomic posterior fossa rather than the primary tumor volume with a margin. This review critically evaluates the potential impact of CSI technique upon the outcome of treatment for medulloblastoma, and suggests future areas of inquiry.

Treatment results for 149 medulloblastoma patients from one institution

PURPOSE

Retrospective analysis of patients with medulloblastoma to determine the effectiveness of previous treatments for medulloblastoma and plan for future management strategies.

METHODS AND MATERIALS

During the period March 1976 to December 1991, 172 patients with cerebellar medulloblastoma were referred to King Faisal Specialist Hospital and Research Center. One hundred and forty-nine patients were treated with curative intent. There were six postoperative deaths, and 10 patients planned for radiotherapy treatment failed to complete the prescribed course. One hundred and thirty-three patients completed a course of radiotherapy after surgery. Adjuvant chemotherapy was not used routinely (six patients only). Tumors were staged retrospectively according to the Chang staging system. There were no T1 patients, 32 patients had T2 tumors, 76 had T3 tumors, and 29 had T4 tumors. The T stage could not be allocated in 12 patients. Ninety-nine patients required a shunting procedure either pre- or postoperatively. Forty-six patients had complete resection of tumor, 91 had incomplete resection, and 6 patients had biopsy only. The extent of resection could not he determined in six patients. The median radiation dose for the whole brain was 34 Gy, spine 32.5 Gy, and posterior fossa 52.8 Gy. Fraction sizes ranged from 1.7-1.8 Gy for craniospinal fields and 2 Gy for the posterior fossa boost. Seventy percent completed the prescribed course within 7 weeks.

RESULTS

Actuarial survival for the whole group of 149 patients was 53% at 5 years and 38% at 10 years. On univariate analysis, patients with T2 tumors did significantly better as compared to patients with T3 and T4 tumors. Survival of patients who had clinical and radiological complete resection of tumor at surgery was significantly better than patients with incomplete tumor removal. The presence of a ventriculoperitoneal (VP) shunt had a significant negative impact on survival. Treatment failure by site was analyzed with respect to the radiation dose. Doses greater than 50 Gy for the posterior fossa, and greater than 30 Gy for craniospinal axis, resulted in significantly better survival. On multivariate analysis, the only significant prognostic factor was the presence of a VP shunt in patients with T2 tumors.

CONCLUSION

T stage, VP shunt, radiation doses and extent of surgery were important prognostic factors. In this study, radiation doses of more than 50 Gy to the posterior fossa and 30 Gy to the craniospinal axis resulted in improved survival.

CNS-85 trial: a cooperative pediatric CNS tumor study--results of treatment of medulloblastoma patients

Between 1985 and 1989, 38 children with newly diagnosed medulloblastoma entered our therapeutic protocol. After surgery and postoperative staging assessments, patients were assigned to risk groups. Eleven with "standard-risk" (SR) tumors were treated with radiation therapy alone, while 27 with "high-risk" (HR) tumors received radiation therapy plus adjuvant chemotherapy with vincristine, methotrexate, VM-26, and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU). After a minimum follow-up of 5 years (range 5-9 years) 21/38 children had developed a recurrence or progression of their disease and 19/38 patients had died. Five-year event-free survival rates and 5-year total survival rates for all 38 patients were 47.4% and 50% respectively. The event-free survival rates at 5 years for SR and HR patients separately were 27.3% and 55.6%, respectively. The corresponding 5-year total survival rates were 27.3% and 59.3%. The differences were not statistically significant. Univariate analysis showed age at diagnosis to be the most important prognostic factor. Infants aged 5 years or less had a significantly shorter event-free survival time than older patients (P = 0.00897). Similar effects were found when total survival time was considered. There were significant differences in outcome in patients receiving different doses of radiation, suggesting a dose-response relationship. A Cox stepwise multivariate analysis showed age at diagnosis as the only independent prognostic factor. Variables relating to treatment entered the model, suggesting that chemotherapy could play an important role in determining outcome.

The applicability of Collins' Law to childhood brain tumors and its usefulness as a predictor of survival

In 1955, Collins made the observation that tumor recurrence in children with Wilms' tumor was correlated with the child's age plus 9 months. This concept of a period of risk for recurrence was later applied to a variety of tumors in children and became known as Collins' Law (CL). The law has been a successful predictor of survival for some children with neural tumors within the central nervous system and a poor predictor for others. We tested Collins' concept of a period of risk for recurrence and extended it to survival for 14 childhood neural tumors described in the Childhood Brain Tumor Consortium (CBTC) database. The CBTC data describe clinical, surgical, and histological details (over a 49-year period in 10 institutions) from 3921 patients under the age of 21 years at the time of their first surgical procedure for a brain tumor. CL was considered to be a good predictor of survival if fewer than 10% of patients who die survive beyond the expiration of the period of risk for that child. We found that CL applied to tumors such as anaplastic astrocytoma, glioblastoma, pineoblastoma, medulloblastoma or "primitive neuroectodermal tumor," teratoma, and germinoma, as well as ependymoma, papilloma, and tumors that could not be classified; it had no predictive value in craniopharyngioma, oligodendroglioma, or plain, fibrillary, pilocytic, or protoplasmic astrocytoma. We had sufficient follow-up data to determine adherence to CL when the child's age at diagnosis was less than 8 years; it is likely that CL applies to older children with these tumors, but we did not have the data to show this unequivocally.

Medulloblastoma and Collins' law: a critical review of the concept of a period of risk for tumor recurrence and patient survival

Collins' law (CL) states that the period of risk for recurrence for a tumor is the age of the patient plus 9 months. Originally a clinical observation in Wilms' tumor, CL has been applied to other tumors such as medulloblastoma (MB). Although CL does not apply to all childhood tumors, it seems to be a valid observation for childhood MB, despite several reports of violations or exceptions to CL in the literature. We sought to test CL in a large population of children with MB from the Childhood Brain Tumor Consortium (CBTC). We analyzed data from 602 children with MB, of whom 421 died and 181 were censored but alive at the last follow-up. We found 16 additional CL exceptions to supplement the 22 already present in the literature. This is both the greatest number of exceptions and the largest MB study population for CL reported to date. We provide clinical data on our 16 uncensored exceptions to CL and critically review those 22 cases cited previously in the literature. All of the CBTC exceptions were under 6 years of age at the time of initial diagnosis and were followed for an average of 7.5 years. All 16 CBTC exceptions died. Children older than 8 years of age could not be followed for a sufficient period of time to be able to state whether CL applies; as age at initial diagnosis increases, the period of observation required to determine CL validity becomes impractically long. Exceptions to CL are rare and amounted to 3.8% of 405 uncensored CBTC patients who died.(ABSTRACT TRUNCATED AT 250 WORDS)

Multivariate analysis of prognostic factors in adult patients with medulloblastoma. Retrospective study of 156 patients

BACKGROUND

Medulloblastoma is a rare disease in adult patients, with an annual incidence rate of 0.05 per 100,000 per year. Results are, therefore, sparse and comprise small series over long periods. The real survival rate, the prognostic factors, the optimal postoperative radiation dose, and the role of adjuvant chemotherapy are still unknown for this disease in adults.

METHODS

The authors collected 156 cases of histologically proven medulloblastoma in patients older than 18 years of age who were treated between January 1975 and December 1991 in 13 French institutions. They analyzed the prognostic factors for survival and the impact of postoperative treatment on survival.

RESULTS

The 5- and 10-year event free survival rates, 61 and 48%, respectively, are similar to those observed in children. The median time to recurrence is 30 months, but late relapses after 5 years remain frequent. Multivariate analysis identified postoperative performance status, spinal axis radiation dose, fourth ventricular floor involvement, and desmoplastic histologic subtype as factors significantly correlated with event free survival. No benefit of concomitant chemotherapy was demonstrated, and complete resection resulted only in severely reduced postoperative performance status.

CONCLUSIONS

The prognostic factors in adult medulloblastoma are comparable to those of medulloblastoma in children, but a new parameter, postoperative performance status, was identified in this adult series. Postoperative craniospinal irradiation remains the standard treatment for adults with medulloblastoma. A reduced dose to the supratentorial compartment should be tested in a prospective protocol.

Medulloblastoma in adults: survival and prognostic factors

The authors report a series of 30 adults with medulloblastoma treated after surgery between 1975 and 1990. Half the patients presented a classical medulloblastoma and the other half presented desmoplastic medulloblastoma. Brainstem infiltration was noted in 3 patients, cerebellar peduncle infiltration in 6 cases and 4 patients had cerebrospinal fluid (CSF) involvement. Tumor resection was achieved in all patients except 1, and in 5 surgery was incomplete. All patients but 2 received postoperative cerebral radiotherapy. Six patients did not receive chemotherapy before radiotherapy, 7 patients received CCNU-Vincristine concomitantly with and after irradiation, 1 patient was given a CHOP regimen, and the remaining 16 patients received the 8 drugs in a 1-day (8/1) regimen before irradiation. The median follow-up time was 104 months. The 5- and 10-year overall survival rates were 58.5% and 41%, respectively. Two toxic deaths occurred under the 8/1 regimen, and no better survival was observed for this group of patients in comparison with those receiving other regimens. Persistence of malignant cells in the CSF, brainstem involvement, cerebellar peduncle infiltration, non-radical surgery and a postoperative performance status (PS) of more than 2 were significantly correlated with an adverse outcome for overall survival in adult patients with medulloblastoma.

Characterisation of a new mouse monoclonal antibody (ONS-M21) reactive with both medulloblastomas and gliomas

We developed an IgG1 mouse monoclonal antibody (ONS-M21) directed against a cell surface antigen of medulloblastomas and gliomas in immunisation of mice with the ONS-76 medulloblastoma cell line. The antibody specifically reacted with medulloblastomas, supratentorial primitive neuroectodermal tumours (SPNETs) and gliomas, but not with other neuroectodermally derived tumours (neuroblastoma and melanoma) or with other kinds of tumours (meningioma, neurinoma, leukaemia, and small cell lung cancer). No reactivity was identified with normal body tissues, including peripheral blood cells. Characterisation of the ONS-M21 antigen showed that it was a trypsin-sensitive glycoprotein with a molecular weight of 80 kDa on SDS-PAGE. The pattern of reactivity and the biochemical properties of this antigen were different from those of other markers of medulloblastoma. These results indicate that ONS-M21 detects a new tumour-associated cell surface antigen specifically expressed by medulloblastomas, SPNETs, and gliomas. This is the first report that medulloblastomas may share common cell surface antigens with gliomas, although most studies have concluded that medulloblastoma has a predominantly neuronal phenotype. The lack of reactivity with normal tissue implies that ONS-M21 has potential applications as both a diagnostic tool and a therapeutic agent.

Ploidy and proliferative index in medulloblastoma: useful prognostic factors?

Paraffin sections from 32 patients with primary medulloblastoma were analysed by flow cytometry for DNA ploidy and proliferative index to assess the value of these measurements in determining prognosis. Twenty-seven samples were informative. Of these 27 patients, 8 had had a total resection. The tumors were diploid in 13 patients and aneuploid in 14. Neither ploidy nor S-phase fraction were prognostic factors for survival, even when considered in conjunction with the type of surgery performed. This is in contrast to other published data, emphasising the need for large multicentre studies of biological prognostic factors in this rare tumour.

Survival results in adult patients treated for medulloblastoma

The records of all 27 adult patients (age, greater than or equal to 16 years) diagnosed with cerebellar medulloblastoma between 1968 and 1986 were reviewed. Twenty-four patients (89%) were treated with postoperative megavoltage irradiation. Twenty of these patients underwent craniospinal irradiation. Sixteen patients received greater than 5000 cGy to the posterior fossa (range, 2340 to 6600 cGy; median, 5490 cGy). Forty-eight percent of patients also received adjuvant chemotherapy. A 5-year and 10-year actuarial survival rate of 48% was achieved. The use of adjuvant chemotherapy did not improve survival in this series. All relapses occurred within 35 months of diagnosis (median time to relapse, 23.5 months), except one patient who had a recurrence in the posterior fossa at 140 months. The posterior fossa was the most common site of treatment failure and represented 50% of all initial relapses. All survivors had no sequelae, except one in whom leukoencephalopathy developed after craniospinal irradiation and intrathecal methotrexate administration. The survival results obtained in this series compare favorably with other reported modern adult medulloblastoma series.

Medulloblastoma: I. Clinical, diagnostic, and therapeutic overview

Medulloblastoma, the most common embryonal tumor of the central nervous system, affects both children and adults. It poses a significant therapeutic challenge in that age-dependent differences exist, not only in their pathobiology, but in the efficacy of chemotherapy and radiotherapy. This is particularly the case in very young children, whose still developing nervous system exhibits a low tolerance to radiotherapy. We review the epidemiology, clinical presentation, radiologic features, and current therapeutic concepts relative to this unique neoplasm. Efforts are made to highlight clinical controversies.

Medulloblastoma in children and in adults: a comparative study

We report on the clinical and pathological characters and factors influencing prognosis in a consecutive series of 20 cases of medulloblastoma presenting in childhood and of 20 cases of the tumour presenting in adulthood. The significant differences which emerged were compared with the findings of the largest published series. Medulloblastoma is more often lateral in site and desmoplastic in histology in adults than in children. On our evidence the age at tumour onset not affect survival.

Role for proton beam irradiation in treatment of pediatric CNS malignancies

The ability to vary the proton energy (depth of beam penetration) and modulate the dose distribution at the end of range permits delivery of an increased dose to the designated cancer-containing volume with a reduced dose to overlying normal brain tissue. The evolution of childhood CNS malignancy following therapy is reviewed to identify radiation response variables indicating where the proton dose distribution will improve the therapeutic ratio. The review documents that of the 1262 children expected to develop CNS malignancy in 1989, only 43% will survive 5 years. About 75% of those with medulloblastoma and over 90% with astrocytoma die from persistent (in-field) disease. When the patient has been treated with radiation, it is accepted that disease persistence indicates the cancer dose was insufficient. Potentially 536 children could show an improved incidence of local control and improved survival from an increased cancer dose available from proton irradiation. As the total dose and volume of brain irradiated is increased about 1800 cGy, brain dysfunction increases, producing a spectrum of functional and intellectual deficits which are age and volume related. About 900 irradiated patients would have fewer in-field histologic and functional changes if the dose to normal brain, or the volume of brain irradiated, is reduced by an improved dose distribution. A proton beam treatment plan, delivering a cancer dose of 7400 cGy, is simulated for a thalamic astrocytoma. The dose distribution of this plan is compared with an x-ray plan used to treat a patient, in which a dose of 5400 cGy was delivered to the astrocytoma. Comparative isodose distributions and dose-volume histograms indicate a decreased integral dose to normal brain and a decreased volume of normal brain irradiated, even as the cancer dose is boosted 2000 cGy with protons.

Improved survival with the use of adjuvant chemotherapy in the treatment of medulloblastoma

Between 1975 and 1989, 108 children with newly diagnosed medulloblastoma/primitive neuroectodermal tumor (MB/PNET) of the posterior fossa were treated at the authors' institution. The patients were managed uniformly, and treatment included aggressive surgical resections, postoperative staging evaluations for extent of disease, and craniospinal radiation therapy with a local boost. Beginning in 1983, children with MB/PNET were prospectively assigned to risk groups; those with "standard-risk" MB/PNET were treated with radiation therapy alone, while those in the "poor-risk" group received similar radiation therapy plus adjuvant chemotherapy with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), vincristine, and cisplatin. The 5-year actuarial disease-free survival rate for all patients treated between 1975 and 1982 was 68%, and 73% when patients who died within 2 weeks after operation were excluded. This survival rate was statistically better for patients treated after 1982 (82%) compared to those treated between 1975 and 1982 (49%) (p less than 0.004). There was no difference in disease-free survival rates over time for children with standard-risk factors; however, there was a significant difference in the 5-year survival rate for poor-risk patients treated prior to 1982 (35%) compared to those treated later (87%) (p less than 0.001). For the group as a whole, a younger age at diagnosis correlated with a poorer survival rate; however, this relationship between age and outcome was significant only for children treated before 1983 (p less than 0.001). These results demonstrated an encouraging survival rate for children with MB/PNET, especially those treated with aggressive surgical resection followed by both radiation therapy and chemotherapy. The results strongly suggest that chemotherapy has a role for some, and possibly all, children with MB/PNET.

Medulloblastoma--prognostic factors and outcome of treatment: review of the Mayo Clinic experience

From March 1965 through December 1984, 58 patients (35 male and 23 female patients; median age, 17 years) with posterior fossa (PF) medulloblastoma underwent surgical treatment and postoperative radiation therapy at our institution. Radiation fields were the craniospinal axis in 39 patients, PF plus spinal axis in 12, PF in 6, and whole brain in 1. Median radiation doses were 43 Gy (22 to 60 Gy) to the PF and 34 Gy (6.2 to 50 Gy) to the spinal axis. Overall 5- and 10-year survivals were 50% and 33%, respectively; 5- and 10-year relapse-free survivals were 46% and 32%. Treatment failed in 34 patients (59%): in 18 who had irradiation to the craniospinal axis (13 had received 50 Gy or less to the PF) and in 16 who had a radiation field of less than the craniospinal axis. A statistically significant (P less than 0.05) improvement in 10-year survival was associated with the following prognostic variables: PF dose of 50 Gy or more, whole-brain irradiation, and spinal axis irradiation. In comparison with subtotal resection, total resection was correlated with better 10-year relapse-free survival but not overall survival. All five patients with initial treatment failure only in the spine had received a radiation dose of 30 Gy or less to the spinal axis. The 2-year survival after relapse was 46% with salvage chemotherapy or irradiation in 23 patients and 0% in the 11 patients who received no further treatment (P less than 0.01).

Results of postoperative irradiation of medulloblastoma in adults

This study analyzes the results of combined surgery and radiation therapy in 13 cases of medulloblastoma in adults treated at the Institute of Oncology in Cracow between 1974-1980. There were 5 women and 8 men. The mean age of the patients was 22.4 years. The overall crude 5-year survival was 62%. Four patients developed recurrence at the primary site (in one case local recurrence was concurrent with pulmonary metastases). The posterior fossa dose in these patients was 2625, 3000, 4800, and 5000 cGy. All 5-year survivors received the posterior fossa dose ranging from 5000 to 5400 cGy. For optimal local control the posterior fossa dose of at least 5400 cGy is recommended, with prior irradiation of the whole cranio-spinal axis.

Treatment of CNS tumours with conventional radiotherapy: the importance of dose & volume factors in tumour control & CNS radiation tolerance

Improved localisation of central nervous system (CNS) tumours resulting from newer diagnostic imaging techniques may allow the therapeutic irradiation of smaller volumes than currently practiced with the possibility of less normal tissue injury and/or the use of higher radiation doses. The influence of radiation dose and volume on the control rates for various types of CNS tumour and on the radiation tolerance of CNS tissue is imperfectly understood. Available data on these fundamental issues in the radiation treatment of CNS tumours is reviewed.