Katja von Hoff

Purpose Radiotherapy (RT) is associated with improved survival in atypical teratoid/rhabdoid tumor (ATRT); however, optimal RT delivery is unknown. A meta‐analysis was conducted for disseminated (M+) ATRT receiving focal or craniospinal radiation (CSI). Methods After abstract screening, 25 studies (1995–2020) contained necessary patient, disease, and radiation treatment information ( N = 96). All abstract, full text, and data capture were independently double‐reviewed. The corresponding author was contacted for cases of insufficient information. Response to pre‐radiation chemotherapy ( N = 57) was categorized as complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD). Univariate and multivariate statistics were performed to investigate survival correlation. Patients with M4 disease were excluded. Results The 2‐ and 4‐year overall survival (OS) was 63.8% and 45.7%, respectively, with a median follow‐up of 2 years (range 0.3–13.5). The median age was 2 years (range 0.2–19.5), and 96% received chemotherapy. On univariate analysis, gross total resection (GTR, p = .0007), pre‐radiation chemotherapy response ( p < .001), and high‐dose chemotherapy with stem cell recuse (HDSCT, p = .002) correlated with survival. On multivariate analysis, pre‐radiation chemotherapy response ( p = .02) and GTR ( p = .012) retained survival significance as compared to a trend for HDSCT ( p = .072). Comparisons of focal RT (vs. CSI) and greater than or equal to 5400 cGy primary dose were nonsignificant. Following CR or PR, a statistical trend favored focal radiation ( p = .089) over CSI. Conclusion Chemotherapy response prior to RT and GTR correlated with improved survival on multivariate analysis for ATRT M+ receiving RT. No benefit was observed for CSI compared to focal RT among all patients and following favorable chemotherapy response, inviting further study of focal RT for ATRT M+.

Background The prognostic impact of clinical risk factors and DNA methylation patterns in sonic hedgehog (SHH)-activated early childhood desmoplastic/nodular medulloblastoma (DMB) or medulloblastoma with extensive nodularity (MBEN) were evaluated to better identify patients at risk for relapse. Methods One hundred and forty-four patients with DMB (n = 99) or MBEN (n = 45) aged <5 years and treated with radiation-sparing approaches, including intraventricular methotrexate in 132 patients were evaluated. Results Patients with DMB had less favorable 5-year progression-free survival than MBEN (5y-PFS, 71% [DMB] vs. 93% [MBEN]). Patients aged >3 years were associated with more unfavorable 5y-PFS (47% [>3 years] vs. 85% [<1 year] vs. 84% [1–3 years]). DNA methylation profiles available (n = 78) were reclassified according to the 2021 WHO classification into SHH-1 (n = 39), SHH-2 (n = 38), and SHH-3 (n = 1). Hierarchical clustering delineated 2 subgroups among SHH-2: SHH-2a (n = 19) and SHH-2b (n = 19). Patients with SHH-2b medulloblastoma were older, predominantly displayed DMB histology, and were more often located in the cerebellar hemispheres. Chromosome 9q losses were more frequent in SHH-2b, while few chromosomal alterations were observed in SHH-2a. SHH-2b medulloblastoma carried a significantly increased relapse risk (5y-PFS: 58% [SHH-2b] vs. 83% [SHH-1] vs. 95% [SHH-2a]). Subclassification of SHH-2 with key clinical and cytogenetic characteristics was confirmed using 2 independent cohorts (total n = 188). Gene mutation analysis revealed a correlation of SHH-2a with SMO mutations. Conclusions These data suggest further heterogeneity within early childhood SHH-DMB/MBEN: SHH-2 splits into a very low-risk group SHH-2a enriched for MBEN histology and SMO mutations, and SHH-2b comprising older DMB patients with a higher risk of relapse.