Abstract
Abstract BACKGROUND Ependymoma (EPN) is not a uniform disease but represents different tumor types with biological and clinical heterogeneity. Some types have an excellent prognosis; others display frequent relapse. However, the pattern of when and where different types of EPN relapse is largely unknown. METHODS We assembled 552 intracranial EPN from pediatric (n=445) and adult (n=107) patients from European and Northern American cohorts and correlated DNA methylation patterns and copy-number alterations with clinical information. Median age at diagnosis was 13.4±18.8 (0.1 – 80) years. RESULTS In 271/552 (49.1%) of included EPN relapse occurred. First relapses occurred in the initial tumor bed in 70.9%, 22.4% were metastatic only, and 6.7% were combined local and metastatic. First relapses of PF-EPN-B (PF: posterior-fossa) and PF-EPN-SE (SE: subependymoma) occurred later than of PF-EPN-A, ST-EPN-YAP (ST: supratentorial), or ST-EPN-ZFTA (median time to relapse: 4.3 and 6.0 years vs. 1.9/1.0/2.5 years; p<0.01). Metastatic or combined recurrences in PF-EPN-B and -A occurred more often in the spinal cord than in ST-EPN-ZFTA (75.0% and 40.0% vs. 12.5%; p<0.01). In the latter, relapse occurred more frequently when harboring an alternative fusion or CDNK2A loss (p<0.01, respectively). No distant relapses were observed in ST-EPN-YAP (n=9) or PF-EPN-SE (n=60). Post-relapse survival (PRS) was poor for PF-EPN-A and ST-EPN-ZFTA (5-year PRS: 44.5±4.4/ 47.8±9.1%), whereas PF-EPN-B and PF-EPN-SE displayed a 5-year PRS of 89.5±7.1/ 90.0±9.5% (p=0.03). However, 10-year PRS for PF-EPN-B dropped to 45.8±17.3%. CONCLUSIONS Relapse patterns of specific EPN types are different. Duration of surveillance and diagnostics should be planned incorporating entity-specific relapse information. Follow-up should be performed longer than 5 years after diagnosis. Spinal MRI should be considered as standard procedure during surveillance, particularly for PF-EPN-A, PF-EPN-B and ST-EPN-ZFTA.
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