Importance of radiation time and dose factors on outcome for childhood medulloblastoma*

Survival and prognostic factors in adult medulloblastoma: the Salah Azaiz Institute experience

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in children. This entity in adulthood is rare. The aim of our study is to evaluate therapeutic results and prognostic factors of adult medulloblastoma treated at our institute with post-operative radiotherapy.

METHODS

We retrospectively reviewed a cohort of 55 patients with medulloblastoma who underwent radiation in the department of radiation oncology of institute Salah Azaiz (Tunis) over a 18-year period (1994-2012).

RESULTS

The surgery was total or subtotal resection in 73% of cases. Forty-eight patients received radiotherapy to the entire craniospinal axis as part of the curative treatment. The median interval from surgery to the initiation of radiotherapy was 83 days. Etoposide-cisplatin chemotherapy was only performed in metastatic patients (n = 4). The 5-years and 10-years overall survival rates were respectively 53 and 34%. The dose of radiotherapy to the craniospinal axis was a prognostic factor. The 5-years and 10-years event-free-survival rates were 64 and 41%. Reduction in the dose of radiotherapy to the craniospinal axis and fourth ventricular floor involvement were correlated with a worse event-free survival.

CONCLUSION

Our results, compared to those of the literature, conclude that the reduction in the dose of radiotherapy to the craniospinal axis (<34 Gy) in the standard risk group of adult medulloblastoma could not be done without chemotherapy. In the high-risk group of adult medulloblastoma, radiotherapy to the cerebrospinal axis at the dose of 36 Gy with chemotherapy, is required for disease control.

Risk Factors for Survival in Patients With Medulloblastoma: A Systematic Review and Meta-Analysis

Background

Conventional parameters show limited and unreliable correlations with medulloblastoma prognosis.

Aim

To evaluate the factors influencing overall survival (OS), event-free survival (EFS), and progression-free survival (PFS) in patients with medulloblastoma.

Methods

PubMed, EMBASE, the Cochrane Library, and Web of Science were searched for studies published up to May 2021. The associations between various clinical and treatment factors and survival parameters were assessed.

Results

Twenty-nine studies (8455 patients) were included. Desmoplastic medulloblastoma (HR=0.41, 95%CI: 0.31-0.56), M0 disease (HR=2.07, 95%CI: 1.48-2.89), WNT, SSH, group 4 (all P<0.05 vs. group 3), GTR vs. STR (HR=1.37, 95%CI: 1.04-1.08), radiotherapy (HR=0.45, 95%CI: 0.20-0.80), craniospinal irradiation (HR=0.49, 95%CI: 0.38-0.64), and high 5hmC levels (HR=2.90, 95%CI: 1.85-4.55) were associated with a better OS. WNT, SSH, group 4 (all P<0.05 vs. group 3), residual tumor ≤1.5 cm2 (HR=2.08, 95%CI: 1.18-3.68), GTR vs. STR (HR=1.31, 95%CI: 1.03-1.68), craniospinal irradiation (HR=0.46, 95%CI: 0.37-0.57), high 5hmC levels (HR=3.10, 95%CI: 2.01-4.76), and <49 days between resection and radiotherapy (HR=2.54, 95%CI: 1.48-4.37) were associated with better PFS. Classic vs. desmoplastic medulloblastoma (HR=1.81, 95%CI: 1.04-3.16), SSH, WNT (both P<0.05 vs, non-SSH/non-WNT), GTR vs. STR (HR=2.01, 95%CI: 1.42-2.85), and radiotherapy (HR=0.31, 95%CI: 0.15-0.64) were associated with a better EFS.

Conclusion

Histology, molecular subgroup, GTR, and radiotherapy are significantly associated with survival parameters in patients with medulloblastoma. Nevertheless, high-quality prospective cohort studies are necessary to improve the conclusions.

Real-world data for pediatric medulloblastoma: can we improve outcomes?

Medulloblastoma (MB) is a malignant embryonal tumor that develops especially in childhood, with overall survival (OS) at 5 years of up to 70%. The objective of this study is to analyze treatment delivery variables in a retrospective cohort and evaluate the impact of these treatment quality parameters on survival. From 2000 to 2018, 40 pediatric patients with medulloblastoma, treated according to current international protocols, were retrospectively analyzed. Treatment delivery quality indicators were analyzed including the extent of surgery, radiotherapy (RT) parameters, and chemotherapy variables, related with time and dose-intensity deviations. With a median follow-up of 74 months (range, 6-195), OS at 5 years was 74 ± 7%, 81 ± 8% for standard-risk, and 55 ± 16% for high-risk patients (p = 0.090). Disease-free survival at 5 years was not significantly affected by extent of surgery (p = 0.428) and RT-related variables such as surgery-RT interval (p = 0.776) neither RT duration (p = 0.172) or maintenance chemotherapy compliance (p = 0.634). Multivariate analysis identified risk groups predictive of worse DFS (p = 0.032) and leptomeningeal dissemination associated with inferior OS (p = 0.029).Conclusion: Treatment delivery optimization has improved survival rates of patients with MB. Despite this, in our study, we have not established a clear influence of the considered radiotherapy and chemotherapy treatment quality parameters on outcomes. What is Known: • Improvement in treatment modalities during the last decades has reached a 5-year OS of up to 70% in these patients. • Extent of resection and radiotherapy parameters such as interval between surgery-radiotherapy and radiotherapy duration has been described as probable survival prognostic factors. What is New: • Differences in medulloblastoma survival rates between prospective studies and retrospective series. • The impact on survival of the three main treatment variables, surgery, radiotherapy and chemotherapy, susceptible to improvement.

Prolongation of radiotherapy duration is associated with inferior overall survival in patients with pediatric medulloblastoma and central nervous system primitive neuroectodermal tumors

BACKGROUND

The importance of radiotherapy (RT) duration in medulloblastoma in the modern era of chemotherapy has not been well elucidated. The aim of this study was to determine the impact of RT treatment duration on overall survival (OS) in pediatric medulloblastoma and cenral nervous system neuroectodermal tumors (PNETs).

METHODS

The National Cancer Database (NCDB) was queried to identify patients with newly diagnosed medulloblastoma and CNS PNETs diagnosed between 2004 and 2014. Patients were excluded if they had extraneural metastasis, did not receive standard craniospinal irradiation dose, had a nonstandard total dose outside of 54 or 55.8 Gy, did not receive adjuvant chemotherapy, or if the RT duration was outside of the expected range of 37 to 80 days. The Kaplan-Meier estimator was used to estimate the association between RT duration (≤45 days or >45 days) and OS. Multivariate Cox regression was used to assess other confounders of OS.

RESULTS

Six-hundred twenty-five patients met inclusion criteria, of which 181 were assigned to the "RT long" (>45 days) cohort (29.0%) and 444 (71.0%) to the "RT short" group (≤45 days). The five-year OS for the "RT short" compared with "RT long" cohort was 82.2% versus 70.9%, respectively (log-rank, P < 0.0037). For average risk patients, the five-year OS was 84.6% versus 86.4% for "RT short" and "RT long," respectively (log-rank, P = 0.40). However, for high-risk patients, five-year OS was 77.7% versus 51.0% (log-rank, P < 0.0001) in the "RT short" and "RT long" cohorts.

CONCLUSION

For patients with high-risk medulloblastoma and CNS PNETs, RT duration >45 days was associated with inferior OS.

[Evolution of the management of pediatric and adult medulloblastoma]

Medulloblastoma are cerebellar tumours belonging to the group of primitive neuroectodermal tumours (PNET) and are the most common malignant brain tumours of childhood. These tumours are rare and heterogeneous, requiring some multicentric prospective studies and multidisciplinary care. The classical therapeutic approaches are based on clinical, radiological and surgical data. They involve surgery, radiation therapy and chemotherapy. Some histological features were added to characterize risk. More recently, molecular knowledge has allowed to devise risk-adapted strategies and helped to define groups with good outcome and reduce long-term sequelae, improve the prognostic of high-risk medulloblastoma and develop new therapeutic tools.

[Medulloblastomas: review]

INTRODUCTION

The term of "medulloblastoma" refers to cerebellar tumors belonging to the family of primitive neuro-ectodermic tumors (PNET). Medulloblastomas represent 40% of cerebellar tumors, 15 to 20% of brain tumors and the first cause of malignant brain tumors in childhood. Seventy to 80% of cases are diagnosed in children versus 20 to 30% in adults.

UPDATED KNOWLEDGE

Diagnosis is based on clinical and radiological exams, and proved on pathological analysis in association with molecular biology. Treatment comprises surgery, craniospinal radiotherapy except for children under five years of age and chemotherapy according to age and high-risk criteria. Medulloblastoma is a rare case of a central nervous system tumor which is radio- and chemo-sensitive. Treatment goals are, on one hand, to improve the survival rates and, on the other hand, to avoid late neurocognitive, neuroendocrine and orthopedic side effects related to radiation therapy, notably in children. The prognosis is relatively good, with a five year survival rate over 75% after complete resection of a localized tumor although sequelae may still compromise outcome.

PERSPECTIVES AND CONCLUSION

Management of patients with medulloblastoma implies a multidisciplinary approach combining the contributions of neurosurgery, neuroradiology, pediatric oncology, neuro-oncology and radiotherapy teams.

A phase II study of preradiotherapy chemotherapy followed by hyperfractionated radiotherapy for newly diagnosed high-risk medulloblastoma/primitive neuroectodermal tumor: a report from the Children's Oncology Group (CCG 9931)

PURPOSE

To verify feasibility and monitor progression-free survival and overall survival in children with high-risk medulloblastoma and noncerebellar primitive neuroectodermal tumors (PNETs) treated in a Phase II study with preradiotherapy chemotherapy (CHT) followed by high-dose, hyperfractionated craniospinal radiotherapy (CSRT).

METHODS AND MATERIALS

Eligibility criteria included age >3 years at diagnosis, medulloblastoma with either high M stage and/or >1.5 cm(2) postoperative residual disease, and all patients with noncerebellar PNET. Treatment was initiated with five alternating monthly cycles of CHT (A [cisplatin, cyclophosphamide, etoposide, and vincristine], B [carboplatin and etoposide], A, B, and A) followed by hyperfractionated CSRT (40 Gy) with a boost to the primary tumor (72 Gy) given in twice-daily 1-Gy fractions.

RESULTS

The valid study group consisted of 124 patients whose median age at diagnosis was 7.8 years. Eighty-four patients (68%) completed the entire protocol according to study guidelines (within 9 months), and the median time to complete CSRT was 1.6 months. Major reasons for failure to complete CHT included progressive disease (17%) and toxic death (2.4%). The 5-year progression-free survival and overall survival rates were 43% +/- 5% and 52% +/- 5%, respectively. No significant differences were detected in subset analysis related to response to CHT, site of primary tumor, postoperative residual disease, or M stage.

CONCLUSIONS

The feasibility of this intensive multimodality protocol was confirmed, and response to pre-RT CHT did not impact on survival. Survival data from this protocol can not be compared with data from other studies, given the protocol design.

Pediatric medulloblastoma: toxicity of current treatment and potential role of protontherapy

Post-operative craniospinal irradiation and systemic chemotherapy are both necessary in the treatment of pediatric medulloblastoma. Late toxicity is a major problem in long term survivors and significantly affects their quality of life. We have systematically reviewed the literature to examine data on late toxicity, specifically focusing on: endocrine function, growth and bone development, neurocognitive development, second cancers, ototoxicity, gynecological toxicity and health of the offspring, cardiac toxicity and pulmonary toxicity. In this paper, we describe qualitatively the kind of detected side effects and, whenever possible, try to assess their incidence and the relative role of craniospinal irradiation (as opposed to other treatments and to the disease itself) in producing them. Subsequently we examine the possible approach to reduce unwanted effects from craniospinal irradiation to target and non-target tissues and we consider briefly the role of hyperfractionation, tomotherapy and IMRT. We describe the characteristics of protontherapy and its potential for non-target tissues toxicity reduction reviewing the existing physical and dosimetric studies and the (still very limited) clinical experiences. Finally we propose intensity modulated spot scanning protontherapy with multiportal simultaneous optimization (IMPT) as a possible tool for dose distribution optimization within different areas of CNS and potential reduction of target tissues toxicity.

Paediatric medulloblastoma: patterns of care and radiotherapy quality assurance in Australia

The purpose of this study was to document how children in Australia with medulloblastoma are being treated and to evaluate the quality of radiotherapy (RT) delivered. The Radiotherapy Database of the Australian and New Zealand Children's Haematology and Oncology Group was used to identify 46 children with medulloblastoma younger than the age of 15 years treated with radical intent by craniospinal irradiation between 1997 and 1999 inclusively. Twenty-six patients had completely resected disease without evidence of disease spread. Of these, 16 patients received a craniospinal RT dose of <25 Gy in addition to chemotherapy. RT treatment immobilization methods varied, as did planning methods. RT dose to critical structures was recorded on treatment plans for only 15% of patients. The average systematic error in shield placement at the posterior orbit was 5.2 mm, and two-thirds of patients were 'overshielded' at this site. Adequate coverage of the distal end of the thecal sac was achieved in fewer than 50% of on-treatment verification films for 21 of 45 patients. With a reduction in RT dose to the craniospinal axis for paediatric medulloblastoma, greater attention is needed for patient immobilization, documentation of RT dose to critical structures and the placement and reproducibility of shielding.