Review of 20 years of Adult Medulloblastoma Treatment at a High-Volume Center – Chemotherapy Prescription Trends and Survival

Abstract

<h3>Purpose/Objective(s)</h3> Medulloblastomas are WHO grade 4 tumors and represent less than 1% of adult brain malignancies. Standard of care is maximal safe resection follow by craniospinal and primary site radiation – the role for chemotherapy has been unclear. The objective of this study was to review 20-year chemotherapy prescribing trends in adult medulloblastoma patients at a high-volume center, with secondary objectives assessing overall and progression free-survival. We hypothesized that primary chemotherapy (concurrent or adjuvant) would be associated with prolonged survival and that patients treated in the most recent decade would have received chemotherapy more often. <h3>Materials/Methods</h3> A retrospective review was performed of adult medulloblastoma patients at a high-volume center from 1999-01-01–2020-12-31. Eligible patients were 18 years and older with a pathologic diagnosis of medulloblastoma – those with supratentorial primitive neuroectodermal tumors were excluded. Descriptive statistics were used to present population data and Kaplan–Meier estimators for survival analysis. <h3>Results</h3> Forty-nine patients were eligible; median age was 30 and male: female ratio was 2:1. Desmoplastic and classical histologies were the most common. Molecular subgroup was available for 6 patients, with SHH predominating. Of all patients, 47% (23/49 were classified as high risk – most commonly due to large cell/anaplastic histology or large residual. Only 10 (20%) received primary chemotherapy, 70% of which had high risk disease. Of the patients who received primary chemotherapy, 30% went on to receive chemotherapy for recurrence or metastases; of the entire population, this was only 39%. Primary regimens were mainly cisplatin/lomustine/vincristine, while recurrence regimens were often cisplatin/etoposide. The majority who received primary chemotherapy were treated from 2010–2020. Median overall survival was 7.8 years (95% CI 5.7–∞), with 1-, 5-, and 10-year survival 95.8%, 67.5% and 42.2% respectively. Overall survival was marginally better for those who did not receive primary chemotherapy (8.5 years) vs those who did (7.4 years) <i>but this was non-significant</i>. The main chemotherapy toxicity was hematologic and neuropathy - 90% of primary chemotherapy patients experienced toxicity <h3>Conclusion</h3> This study reviewed 20 years of treatment trends for a group of adult medulloblastoma patients at a high-volume center. We found only a small proportion of patients received chemotherapy as their primary treatment with surgery and radiation. Patients who received primary chemotherapy had marginally worse overall survival, but this was non-significant – perhaps due to baseline worse clinical status not captured by the definition of high vs. intermediate risk disease. Despite calls for adjuvant chemotherapy for all adult medulloblastoma patients, there is clinical equipoise and future randomized trials are needed.