In the northeastern part of the Grenville Province, along the gulf of St Lawrence, cordierite is widespread in the migmatites of Baie Jacques Cartier (BJC) and Baie des Ha! Ha! (BHH). In the BJC area, rafts of mesosome occur in a pervasive network of leucosome consisting of cordierite-bearing pegmatite. In BHH, however, the mesosome and leucosome are well segregated and locally separated by thin biotite -hornblende melanosomes.Leucosomes in the BJC area record the highest temperatures (oxide thermometry =900"C), whereas leucosomes of BHH and mesosomes of both areas indicate peak temperatures around 800°C (oxide thermometry; biotite-garnet thermometry with fluorine-rich biotite). Peak pressures were constrained at 720 MPa using the IlrnSil-Qtz-Grt-Rt (GRAIL) equilibrium.The area is thought to have undergone extensive melting under relatively modest pressures. The highest temperatures recorded in the BJC area are probably related to a pervasive impregnation of this terrane by aluminous granitic melts.Most post-peak P-T estimates for the mesosomes fall on a nearly isobaric, clockwise, P-T path (0.6 MPaPC) with the exception of the high-temperature leucosomes of BJC. which fall about 100°C away from this path; this is additional evidence for the external origin of these leucosomes. The ultimate source of heat that generated the migmatites is thus though to be an underlying plutonic complex (anorthosite?).
List of abbreviations used in the text andfiguresAlm And Andr Bt Crd Grt Grs Hem Hc Ilm Kfs Hog KY Mag PI PrP Qtz Sil SPS Rt USP
Background
ETMRs are a newly recognized rare paediatric brain tumor with alterations of the C19MC microRNA locus. Due to varied diagnostic practices and limited clinical data, disease features and determinants of outcome are poorly defined. We performed an integrated clinico-pathologic and
molecular analyses of 159 primary ETMRs to define clinical phenotypes, identify predictors of survival and critical treatment modalities for this orphan disease.
Methods
Primary ETMR patients were identified from the Rare Brain Tumor Consortium
(rarebraintumorconsortium.ca) global registry using histopathologic and molecular assays. Event-Free (EFS) and Overall Survival (OS) for 108 patients treated with curative multi-modal regimens were determined using Cox proportional hazard and log rank analyses.
Findings
ETMRs were predominantly non-metastatic (73%) tumors arising from multiple sites; 55% were cerebral tumors, 45% arose at sites characteristic of other brain tumors. Hallmark C19MC alterations were seen in 91%; 9% were ETMR-NOS. Survival and hazard analyses showed a 6 month median
EFS and 2-4yr OS of 27-29% with metastatic disease (HR=0.44, 95% CI 0.26-0.74; p=0.002) and brainstem location (HR=0.40, 95% CI 0.021-0.75; p=0.005) correlating with adverse OS. Gross total resection (GTR: HR=0.38, 95% CI 0.21-0.68; p=0.001), high dose chemotherapy (HDC: HR=0.55, 95% CI 0.31-0.97; p=0.04) and radiation (RT: HR=0.32, 95% CI 0.16-0.60; p=<0.001) correlated with improved EFS and OS in multi-variable analyses. EFS and OS for patients treated with only conventional dose chemotherapy (CC) was 0% and respectively 37%+/-14% and 32%+/-13% for patients treated with HDC. Patients with GTR or sub-total resection (STR) treated with HDC and RT had superior EFS (GTR 73%+/-14%, p=0.018; STR 67%+/-19% p=0.009) and OS (GTR 66%+/-17%, p=0.05; STR 67%+/-16%, p=0.005). Amongst 21 long-term survivors (OS 24-202
months); 38%, 24% and 24% respectively received craniospinal, focal or no RT.
Interpretation: Prompt molecular diagnosis and post-surgical treatment with multi-modal therapy
tailored to patient-specific risk features improves ETMR survival.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.