Proton MR spectroscopy shows improved performance to segregate high-grade astrocytoma subgroups when defined with the new 2021 World Health Organization classification of central nervous system tumors

OBJECTIVES

The 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors prioritizes isocitrate dehydrogenase (IDH) mutation to define tumor types in diffuse gliomas, in contrast to the 2016 classification, which prioritized histological features. Our objective was to investigate the influence of this change in the performance of proton MR spectroscopy (1H-MRS) in segregating high-grade diffuse astrocytoma subgroups.

METHODS

Patients with CNS WHO grade 3 and 4 diffuse astrocytoma, known IDH mutation status, and available 1H-MRS were retrospectively retrieved and divided into 4 groups based on IDH mutation status and histological grade. Differences in 1H-MRS between groups were analyzed with the Kruskal-Wallis test. The points on the spectrum that showed the greatest differences were chosen to evaluate the performance of 1H-MRS in discriminating between grades 3 and 4 tumors (WHO 2016 defined), and between IDH-mutant and IDH-wildtype tumors (WHO 2021). ROC curves were constructed with these points, and AUC values were calculated and compared.

RESULTS

The study included 223 patients with high-grade diffuse astrocytoma. Discrimination between IDH-mutant and IDH-wildtype tumors showed higher AUC values (highest AUC short TE, 0.943; long TE, 0.864) and more noticeable visual differences than the discrimination between grade 3 and 4 tumors (short TE, 0.885; long TE, 0.838).

CONCLUSION

Our findings suggest that 1H-MRS is more applicable to classify high-grade astrocytomas defined with the 2021 criteria. Improved metabolomic robustness and more homogeneous groups yielded better tumor type discrimination by 1H-MRS with the new criteria.

CLINICAL RELEVANCE STATEMENT

The 2021 World Health Organization classification of brain tumors empowers molecular criteria to improve tumor characterization. This derives in greater segregation of high-grade diffuse astrocytoma subgroups by MR spectroscopy and warrants further development of brain tumor classification tools with spectroscopy.

KEY POINTS

• The new 2021 updated World Health Organization classification of central nervous system tumors maximizes the role of molecular diagnosis in the classification of brain tumors. • Proton MR spectroscopy performs better to segregate high-grade astrocytoma subgroups when defined with the new criteria. • The study provides additional evidence of improved metabolic characterization of brain tumor subgroups with the new criteria.

Factores asociados con supervivencia a cinco años en niños con astrocitoma cerebral

Introducción

La segunda causa de muerte infantil es el cáncer, del cual las leucemias y los tumores del sistema nervioso central son las presentaciones más frecuentes; de los últimos, los astrocitomas representan 40 %.

Objetivo

Identificar los factores asociados con la supervivencia a cinco años en niños con astrocitoma cerebral.

Método

Estudio de casos y controles anidado en una cohorte retrospectiva en pacientes con diagnóstico de astrocitoma cerebral que recibieron tratamiento de diciembre de 2006 a enero de 2010. Se realizó estadística descriptiva y prueba de chi cuadrado; para evaluar la supervivencia se utilizó el método de Kaplan-Meier.

Resultados

Se incluyeron 21 pacientes con diagnóstico de astrocitoma cerebral; la supervivencia fue de 76 % a cinco años, el astrocitoma pilocítico fue el más frecuente (61 %), con una edad media de siete años; predominó el sexo masculino, la edad al fallecimiento osciló entre los ocho y 12 años (p = 0.022); 80 % de los pacientes fallecidos tuvo tumor con localización infratentorial d (RM = 17.3, IC 95 % = 1-622, p = 0.01). No hubo diferencia en la supervivencia atribuible al tratamiento.

Conclusión

La supervivencia a cinco años fue de 76 %; el factor de riesgo significativo que la limita es la localización infratentorial del tumor.

Introduction

The second cause of children’s death is cancer, with leukemia and central nervous system tumors being the most common, among which astrocytomas account for 40%.

Objective

To find out the factors associated with 5-year survival in children with cerebral astrocytoma.

Method

Case-control study nested in a retrospective cohort of patients diagnosed with cerebral astrocytoma who received treatment from December 2006 to January 2010. Descriptive statistics and the chi-square test were carried out; the Kaplan-Meier method was used to assess survival.

Results

Twenty-one patients diagnosed with cerebral astrocytoma were included; survival was 76% at 5 years; with pilocytic astrocytoma being the most common (61%); mean age was 7 years, and male gender was predominant; age at death ranged from 8 to 12 years (p = 0.022), with 80% of deceased patients having infratentorial localization (OR = 17.3; 95% CI = 1-622; p = 0.01). There was no treatment-attributable survival difference.

Conclusions

Five-year survival was 76%; the limiting risk factor is tumor infratentorial localization.