Pseudoprogression Is Frequent After Front-Line Radiation Therapy in Pediatric Low-Grade Glioma: Results From the German Low-Grade Glioma Cohort.

PURPOSE: Expansion of magnetic resonance imaging T2- or T1-tumor lesion volume after radiation therapy (RT) may indicate pseudoprogression (PsPD). The differentiation between true progression and PsPD is a clinical challenge and underinvestigated in pediatric low-grade glioma (LGG). We evaluated radiologic criteria for PsPD after front-line RT and investigated the frequency and duration of PsPD after 3 RT-modalities within the framework of the German pediatric multicenter LGG-studies. METHODS AND MATERIALS: Baseline and follow-up magnetic resonance imaging scans of 136 patients (72 male [52.9%], median age at start of RT of 11.3 years [range, 0.8-25.9]) of the Society for Pediatric Oncology-LGG 2004 study and LGG-registry cohorts (125iodine-interstitial [IS] RT [n = 51], photon-beam [XRT; n = 60], or proton-beam RT [PBT; n = 25]) were centrally evaluated for increasing: (1) total tumor-associated T2 lesion, (2) focal tumor-associated T2 lesion, and (3) contrast-enhancing tumor during a period of 24 months after RT. The pattern of these criteria initiated "suspicion" of PsPD; their evolution determined "definite" PsPD. RESULTS: Definite PsPD was radiologically determined in 54 of 136 (39.7%) without differences in frequency between RT-modalities: IS 22 of 48 versus XRT 24 of 54 versus PBT 11 of 20; P = .780. Definite PsPD occurred at median 6.3 months (IS 7.2 months; XRT 4.4 months; PBT 6.5 months) after RT-initiation and persisted for median 7.2 months (IS 8.5 months; XRT 7 months; PBT 7.4 months). Appearance of necrosis within the focal tumor-associated T2 lesion proved to be a relevant associated predictor of definite PsPD (P < .001). CONCLUSIONS: PsPD is frequent after irradiation of pediatric LGG and independent of the RT modality (IS vs XRT vs PBT). Adequate identification of PsPD versus true progression is imperative to prevent unneeded salvage treatment.

Doubling Recruitment of Pediatric Low-grade Glioma within Two Decades does not change Outcome - Report from the German LGG Studies.

BACKGROUND: Successive multicenter studies for pediatric low-grade glioma (LGG) in Germany were accompanied by a doubling of annual recruitment over 2 decades. We investigated whether this increase conveyed a change of epidemiologic characteristics or survival. METHODS AND RESULTS: Participating centers reported 4634 patients with the radiologic/histologic diagnosis of LGG (1996-2018), rising from 109 to 278/year. Relating these numbers to all pediatric CNS tumors registered at the German Childhood Cancer Registry, the LGG fraction and annual crude incidence rates increased (32% to 51%; 0.94 to 2.12/100,000 children/adolescents<15 years). The consecutive LGG studies recruited 899 (HIT-LGG 1996), 1592 (SIOP-LGG 2004), and 1836 (LGG-registry) patients with similar distribution of tumor-sites, histology, and dissemination. 5-year overall survival was 96%-98% at median observation time of 8.1 years. Acknowledging unequal follow-up periods, 589/899 (66%), 1089/1582 (69%), and 1387/1836 (76%) patients remained under observation, while 1252/4317 received adjuvant treatment with decreasing frequency of front-line radiotherapy from 16% to 5%. CONCLUSION: Pediatric LGG incidence rates in Germany are now comparable to other European countries. The rise in patient numbers followed implementation of standard-of-care treatment protocols, but did not result in relevant changes of epidemiologic or clinical parameters or survival. Shifts in patient distribution between treatment arms reflect growing acceptance of the LGG therapy algorithm. HINTERGRUND: In den vergangenen 20 Jahren hat sich die jährliche Patientenrekrutierung in den aufeinanderfolgenden multizentrischen Studien für pädiatrische niedrig-gradige Gliome (LGG) in Deutschland verdoppelt. Wir haben untersucht, ob sich mit dieser Zunahme auch epidemiologische Merkmale oder das Überleben verändert haben. METHODIK UND ERGEBNISSE: Zwischen 1996 und 2018 meldeten die teilnehmenden Zentren insgesamt 4634 Patienten mit der radiologischen/histologischen Diagnose eines LGG. Die Zahl stieg von anfangs 109 bis 278 Patienten pro Jahr. Gleichzeitig stieg der Anteil der LGGs an allen am Deutschen Kinderkrebsregister gemeldeten pädiatrischen Hirntumoren von 32 auf 51%, die jährliche Inzidenz erhöhte sich von 0,94 auf 2,12/100 000 Kinder/Jugendliche<15 Jahre. Die aufeinanderfolgenden LGG-Studien rekrutierten 899 (HIT-LGG 1996), 1592 (SIOP-LGG 2004) und 1836 (LGG-Register) Patienten mit vergleichbarer Verteilung von Tumorsitz, Histologie und Disseminierung. Das 5-Jahres-Überleben lag bei einer medianen Nachbeobachtungszeit von 8,1 Jahren zwischen 96 und 98%. Unter Berücksichtigung der ungleich langen Follow-up-Zeit wurden 589/899 (65,5%), 1089/1582 (68,8%) und 1387/1836 (75,5%) Patienten bislang beobachtet, während 1252/4317 eine adjuvante Therapie erhielten. Dabei sank der Anteil der primären Radiotherapie von 16 auf 5%. SCHLUSSFOLGERUNG: Die Rekrutierung pädiatrischer LGG ist dank Implementierung verbindlicher Therapiestandards in Deutschland gestiegen, ohne zu relevanten Veränderungen epidemiologischer oder klinischer Merkmale oder des Überlebens zu führen. Die Inzidenz ist mit anderen europäischen Ländern vergleichbar. Verschiebungen der Patientenzuteilung zwischen den Therapiearmen spiegeln die zunehmende Akzeptanz des LGG-Therapie-Algorithmus wider.

High frequency of disease progression in pediatric spinal cord low-grade glioma (LGG): management strategies and results from the German LGG study group.

BACKGROUND: Knowledge on management of pediatric spinal cord low-grade glioma (LGG) is scarce. METHODS: We analyzed clinical datasets of 128 pediatric patients with spinal LGG followed within the prospective multicenter trials HIT-LGG 1996 (n = 36), SIOP-LGG 2004 (n = 56), and the subsequent LGG-Interim registry (n = 36). RESULTS: Spinal LGG, predominantly pilocytic astrocytomas (76%), harbored KIAA1549-BRAF fusion in 14/35 patients (40%) and FGFR1-TACC1 fusion in 3/26 patients (12%), as well as BRAFV600E mutation in 2/66 patients (3%). 10-year overall survival (OS) and event-free survival (EFS) was 93% ± 2% and 38% ± 5%, respectively. Disseminated disease (n = 16) was associated with inferior OS and EFS, while age ≥11 years and total resection were favorable factors for EFS. We observed 117 patients following total (n = 24) or subtotal/partial resection (n = 74), biopsy (n = 16), or radiologic diagnosis only (n = 3). Eleven patients were treated first with chemotherapy (n = 9) or irradiation (n = 2). Up to 20.8 years after diagnosis/initial intervention, 73/128 patients experienced one (n = 43) or up to six (n = 30) radiological/clinical disease progressions. Tumor resections were repeated in 36 patients (range, 2-6) and 47 patients required nonsurgical treatment (chemotherapy, n = 20; radiotherapy, n = 10; multiple treatment lines, n = 17). Long-term disease control for a median of 6.5 (range, 0.02-20) years was achieved in 73/77 patients following one (n = 57) or repeated (n = 16) resections, and in 35/47 patients after nonsurgical treatment. CONCLUSIONS: The majority of patients experienced disease progression, even after years. Multiple interventions were required for more than a third, yet multimodal treatment enabled long-term disease control. Molecular testing may reveal therapeutic targets.