PNR-25: ETMR—FREQUENCY, CLINICAL PRESENTATION, TREATMENT AND OUTCOME OF 29 PATIENTS TREATED WITHIN THE HIT TRIALS

Embryonal tumours with multilayered rosettes (ETMR) are very rare primitive neuroectodermal tumours of the CNS, characterised by Lin28-immunopositivity and amplification of the 19q13.42 locus (C19MC). Detailed clinical information on treatment and outcome is rare. We present 29 cases (16 male, 13 female) from the HIT trials with centrally re-reviewed neuropathology, all C19MC amplified and Lin28-immunohistochemical positive, diagnosed between 1987 and 2015. The median age was 2.7 years (range 1.0 to 4.6); 18 tumours were located cortical; 4 in the lateral ventricles or 3^rd ventricle; 5 cerebellar and 2 pontine. After surgery, 14 patients had no evidence of disease (NED), 9 had residual tumour and 6 presented with metastasis. 17 patients were treated with Carboplatin/Etoposide, followed by Tandem high-dose chemotherapy (HDCT, Carboplatin/Etoposide, Cyclophosphamide/Thiotepa, n = 11) and craniospinal irradiation (CSI) with 24 Gy for patients with less than CR after HDCT. This group had a 4-year overall survival of 41 ± 14%, significantly better than 12 differently (SKK or primary radiotherapy) treated patients (last patient alive censored after 2 years, p = 0.02). All 8 long-term survivors (2.1 to 9.4 years) had Carboplatin/Etoposide induction and HDCT. Five of eight were irradiated, 3 upfront (2 CSI, 1 local), 2 after relapse; three survived without irradiation. Overall, ETMR is associated with treatment refractory early progression in most patients. Eight of 11 patients, who qualified for HDCT survived. The role of irradiation needs to be clarified. Specific/targeted treatments are urgently needed. Supported by the German Children's Cancer Foundation.