Personalizing age-specific survival prediction and risk stratification in intracranial grade II/III ependymoma

Whole-tumor histogram analysis of postcontrast T1-weighted and apparent diffusion coefficient in predicting the grade and proliferative activity of adult intracranial ependymomas

PURPOSE

To investigate the value of histogram analysis of postcontrast T1-weighted (T1C) and apparent diffusion coefficient (ADC) images in predicting the grade and proliferative activity of adult intracranial ependymomas.

METHODS

Forty-seven adult intracranial ependymomas were enrolled and underwent histogram parameters extraction (including minimum, maximum, mean, 1st percentile (Perc.01), Perc.05, Perc.10, Perc.25, Perc.50, Perc.75, Perc.90, Perc.95, Perc.99, standard deviation (SD), variance, coefficient of variation (CV), skewness, kurtosis, and entropy of T1C and ADC) using FireVoxel software. Differences in histogram parameters between grade 2 and grade 3 adult intracranial ependymomas were compared. Receiver operating characteristic curves and logistic regression analyses were conducted to evaluate the diagnostic performance. Spearman's correlation analysis was used to evaluate the relationship between histogram parameters and Ki-67 proliferation index.

RESULTS

Grade 3 intracranial ependymomas group showed significantly higher Perc.95, Perc.99, SD, variance, CV, and entropy of T1C; lower minimum, mean, Perc.01, Perc.05, Perc.10, Perc.25, Perc.50 of ADC; and higher CV and entropy of ADC than grade 2 intracranial ependymomas group (all p < 0.05). Entropy (T1C) and Perc.10 (ADC) had a higher diagnostic performance with AUCs of 0.805 and 0.827 among the histogram parameters of T1C and ADC, respectively. The diagnostic performance was improved by combining entropy (T1C) and Perc.10 (ADC), with an AUC of 0.857. Significant correlations were observed between significant histogram parameters of T1C (r = 0.296-0.417, p = 0.001-0.044) and ADC (r = -0.428-0.395, p = 0.003-0.038).

CONCLUSION

Whole-tumor histogram analysis of T1C and ADC may be a promising approach for predicting the grade and proliferative activity of adult intracranial ependymomas.

Resection and radiotherapy for intracranial ependymoma: a multiinstitutional 50-year experience

OBJECTIVE

Maximal safe resection is the standard-of-care treatment for adults with intracranial ependymoma. The value of adjuvant radiotherapy remains unclear as these tumors are rare and current data are limited to a few retrospective cohort studies. In this study, the authors assembled a cohort of patients across multiple international institutions to assess the utility of adjuvant radiotherapy in this patient population.

METHODS

Adults with intracranial ependymoma managed surgically at the University Health Network in Toronto, Canada, the University of Oklahoma Health Sciences Center in Oklahoma City, Oklahoma, and The Ottawa Hospital in Ottawa, Canada, were included in this study. The primary end points were progression-free survival (PFS) and overall survival (OS). Clinicopathological variables were assessed in univariate and multivariate Cox proportional hazard models for prognostic significance of PFS and OS.

RESULTS

A total of 122 patients diagnosed between 1968 and 2019 were identified for inclusion. The majority of patients had grade II ependymomas on histopathology (78%) that were infratentorially located (71%), underwent gross-total (GTR) or near-total resection (NTR; 55%), and were treated with adjuvant radiotherapy (67%). A volumetric analysis of the extent of resection in 49 patients with available tumor volume data supported the accuracy of the categorical GTR, NTR, and subtotal resection (STR) groups utilized. Independent statistically significant predictors of poorer PFS in the multivariate analysis included STR or biopsy (vs GTR/NTR; HR 5.4, 95% confidence interval [CI] 2.4-11.0, p < 0.0001) and not receiving adjuvant radiotherapy; cranial (HR 0.5, 95% CI 0.2-1.1) and craniospinal (HR 0.2, 95% CI 0.04-0.5) adjuvant radiotherapy regimens improved PFS (p = 0.0147). Predictors of poorer OS in the multivariate analysis were grade III histopathology (vs grade II: HR 5.7, 95% CI 1.6-20.2, p = 0.0064) and undergoing a biopsy/STR (vs GTR/NTR: HR 9.8, 95% CI 3.2-30.1, p = 0.0001).

CONCLUSIONS

The results of this 50-year experience in treating adult intracranial ependymomas confirm an important role for maximal safe resection (ideally GTR or NTR) and demonstrate that adjuvant radiotherapy improves PFS. This work will guide future studies as testing for molecular ependymoma alterations become incorporated into routine clinical practice.

An Overview of Intracranial Ependymomas in Adults

Simple Summary

Ependymomas are neuroepithelial tumors arising from the central nervous system. They can form anywhere along the neuraxis. In adults, these tumors predominantly occur in the spine. Local therapy with surgery and radiotherapy represents the most effective treatment while systemic chemotherapy should be used in recurrent cases. However, in recent years, a deeper knowledge of molecular mechanisms of these tumors has been made, allowing for new potential systemic treatments. Here, we review these treatment approaches and provide an overview on the molecular characteristics of ependymomas.

Abstract

Ependymomas are rare primary central nervous system tumors. They can form anywhere along the neuraxis, but in adults, these tumors predominantly occur in the spine and less frequently intracranially. Ependymal tumors represent a heterogenous group of gliomas, and the WHO 2016 classification is based essentially on a grading system, with ependymomas classified as grade I, II (classic), or III (anaplastic). In adults, surgery is the primary initial treatment, while radiotherapy is employed as an adjuvant treatment in some cases of grade II and in all cases of anaplastic ependymoma; chemotherapy is reserved for recurrent cases. In recent years, important and interesting advances in the molecular characterization of ependymomas have been made, allowing for the identification of nine molecular subgroups of ependymal tumors and moving toward subgroup-specific patients with improved risk stratification for treatment-decisions and future prospective trials. New targeted agents or immunotherapies for ependymoma patients are being explored for recurrent disease. This review summarizes recent molecular advances in the diagnosis and treatment of intracranial ependymomas including surgery, radiation therapy and systemic therapies.

Development and validation of prognostic nomogram in ependymoma: A retrospective analysis of the SEER database

Background

The prognostic factors for survival in patients with ependymoma (EPN) remain controversial. The aim of this study was to establish a prognostic model for 5‐ and 10‐year survival probability nomograms for patients with EPN.

Methods

Clinical data from the Surveillance, Epidemiology, and End Results (SEER) database were used for patients diagnosed with ependymoma between 2000 and 2018 and were randomized 7:3 into a development set and a validation set. Factors significantly associated with prognosis were screened out using the least absolute shrinkage and selection operator (LASSO) regression. The calibration chart and consistency index (C‐index) are used to evaluate the discrimination and consistency of the prediction model. Decision curve analysis (DCA) was used to further evaluate the established model. Finally, prognostic factors selected by LASSO regression were evaluated using Kaplan–Meier (KM) survival curves.

Results

A total of 3820 patients were included in the prognostic model. Seven survival predictors were obtained by LASSO regression screening, including age, gender, morphology, location, size, laterality, and resection. The prognostic model of the nomogram showed moderate discriminative ability in the development group and the validation group, with a C‐index of 0.642 and 0.615, respectively. In the development set and validation set survival curves, the prognosis index of high risk was less effective than low risk (p < 0.001).

Conclusions

Our nomograms may play an important role in predicting 5 and 10‐year outcomes for patients with ependymoma. This will help assist clinicians in personalized medicine.

Apparent Diffusion Coefficient to Evaluate Adult Intracranial Ependymomas: Relationship to Ki-67 Proliferation Index

BACKGROUND AND PURPOSE

There are important differences in the treatment and prognosis of adult intracranial low-grade ependymomas (grade II) versus anaplastic ependymomas (grade III). We evaluated the value of the apparent diffusion coefficient (ADC) for differentiating these two tumors and further investigated the relationship between ADC values and the Ki-67 proliferation index.

METHODS

Clinical and preoperative magnetic resonance imaging data of 35 cases of adult intracranial ependymomas were retrospectively analyzed, including 20 low-grade ependymomas and 15 anaplastic ependymomas. The minimum ADC (ADCmin), average ADC (ADCmean), and normalized ADC (nADC) were compared between the two groups. Receiver operating characteristic curves were drawn to evaluate the differentiating accuracy of ADC values. The Ki-67 proliferation index of the solid tumor components was also measured to explore its relationship with ADC values.

RESULTS

The ADCmin (.89 ± .17 vs. .66 ± .09 × 10^-3  mm² /second), ADCmean (.98 ± .21 vs. .72 ± .11 × 10^-3 mm² /second), and nADC (1.38 ± .31 vs. 1.02 ± .18 × 10^-3  mm² /second) were significantly higher in adult intracranial low-grade ependymomas than anaplastic ependymomas cases (all P < .05). ADCmean best distinguished the two groups, with an area under the curve value of .900. Using .716 × 10^-3  mm² /second as the optimal threshold, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the two groups were 66.7%, 100%, 85.7%, 100%, and 80%, respectively. ADCmin (r = -.490), ADCmean (r = -.449), and nADC (r = -.425) showed significant negative correlations with the Ki-67 proliferation index (all P < .05).

CONCLUSIONS

ADC values can differentiate adult intracranial low-grade ependymomas and anaplastic ependymomas, which could improve the preoperative diagnostic accuracy of these two tumors and guide their treatment.

Postoperative radiotherapy for WHO grade II-III intracranial ependymoma in adults: An intergroup collaborative study (KROG 18-06/KNOG 18-01)

BACKGROUND AND PURPOSE

To evaluate the impact of adjuvant postoperative radiotherapy (PORT) in adult WHO grade II-III intracranial ependymoma (IEPN).

MATERIALS AND METHODS

A total of 172 pathologically confirmed adult grade II-III IEPN patients from 12 institutions were eligible. Of them, 106 (61.6%) and 66 (38.4%) patients were grade II and III, respectively. For grade II and III IEPNs, 51 (48.1%) and 59 (89.4%) patients received PORT, respectively. The median dose to the primary tumor bed was 54.0 Gy and 59.4 Gy for grade II and III patients, respectively. The prognostic impact of sex, age, performance, WHO grade, location, size, surgical extent, and PORT on local control (LC), progression-free survival (PFS), and overall survival (OS) were evaluated by univariate and multivariate analysis.

RESULTS

The median follow-up period for survivors was 88.1 months. The 5-/10-year LC, PFS, and OS rates were 64.8%/54.0%, 56.4%/44.8%, and 76.6%/71.0%, respectively. On multivariate analysis, adjuvant PORT significantly improved LC (P = 0.002), PFS (P = 0.002), and OS (P = 0.043). Older age (P < 0.001), WHO grade III (P < 0.001), larger tumor size (P = 0.004), and lesser surgical extent (P < 0.001) were also negative factors for OS. Adjuvant PORT also improved LC (P = 0.010), PFS (P = 0.007), and OS (P = 0.069) on multivariate analysis for grade II IEPNs.

CONCLUSION

This multicenter retrospective study supports the role of adjuvant PORT in terms of disease control and survival in adult grade II-III IEPNs. Prospective randomized trials focused on individualized treatment based on molecular subtypes is warranted.

Personalizing age-specific survival prediction and risk stratification in intracranial grade II/III ependymoma

BACKGROUND

Models for estimation of survival rates of patients with intracranial grade II/III ependymoma (EPN) are scarce. Considering the heterogeneity in prognostic factors between pediatric and adult patients, we aimed to develop age-specific nomograms for predicting 3-, 5-, and 8-year survival for these patients.

METHODS

A total of 1390 cases (667 children; 723 adults) of intracranial grade II/III EPNs diagnosed between 1988 and 2015 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database for our study. Univariable and multivariable Cox analyses were employed to identify independent prognostic predictors. Age-specific nomograms were developed based on the results of multivariate Cox analyses. We also evaluated the performance of these predictive models by concordance index, calibration curves, time-dependent receiver operating characteristic curves, and decision curve analyses.

RESULTS

Considerable heterogeneity in prognostic factors was highlighted between pediatric and adult patients. Age, sex, tumor grade, surgery treatment and radiotherapy were identified as significant predictors of overall survival for children, and age, tumor grade, tumor size, surgery treatment, and marital status for adult. Based on these factors, age-specific nomogram models were established and internally validated. These models exhibited favorable discrimination and calibration characteristics. Nomogram-based risk classification systems were also constructed to facilitate risk stratification in EPNs for optimization of clinical management.

CONCLUSIONS

We developed the first nomograms and corresponding risk classification systems for predicting survival in patients with intracranial grade II/III EPN. These easily used tools can assist oncologists in making accurate survival evaluation.