Patterns of care and outcomes for use of concurrent chemoradiotherapy over radiotherapy alone for anaplastic gliomas

Nomogram to Predict the Prognosis of Oligodendroglioma Patients Undergoing Postoperative Adjuvant Chemoradiotherapy

OBJECTIVE

The aim of this study was to develop a prognostic nomogram for predicting the prognosis of oligodendroglioma patients receiving combined chemoradiotherapy (CRT) after surgery.

METHODS

The study used data from the Surveillance, Epidemiology, and End Results (SEER) database between 2000 and 2019. The patients were randomly divided into a development cohort (700 patients) and a validation cohort (244 patients) in a 7:3 ratio. The Cox hazards regression model was used to identify predictors, and a nomogram was constructed to visualize the prognosis. The performance of the prognostic nomogram was evaluated using the consistency index (C-index), clinical net benefit, and calibration.

RESULTS

The nomogram included 5 variables: age, marital status, tumor size, site of lesions, and surgery type. The C-index of the training set and validation set were 0.77 and 0.68, respectively. The calibration plots showed that the nomogram was in good agreement with the actual observation. The clinical decision curve indicated that the nomogram had a good clinical net benefit in oligodendroglioma patients receiving CRT after surgery.

CONCLUSIONS

This study established and verified a prognostic nomogram for a large cohort of oligodendroglioma patients receiving CRT after surgery based on the SEER database. The nomogram may help clinicians provide personalized treatment services and clinical decisions for patients.

Radiation Therapy for IDH-Mutant Grade 2 and Grade 3 Diffuse Glioma: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations for adults with isocitrate dehydrogenase (IDH)-mutant grade 2 and grade 3 diffuse glioma, as classified in the 2021 World Health Organization (WHO) Classification of Tumours. It includes indications for radiation therapy (RT), advanced RT techniques, and clinical management of adverse effects.

METHODS

The American Society for Radiation Oncology convened a multidisciplinary task force to address 4 key questions focused on the RT management of patients with IDH-mutant grade 2 and grade 3 diffuse glioma. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

A strong recommendation for close surveillance alone was made for patients with oligodendroglioma, IDH-mutant, 1p/19q codeleted, WHO grade 2 after gross total resection without high-risk features. For oligodendroglioma, WHO grade 2 with any high-risk features, adjuvant RT was conditionally recommended. However, adjuvant RT was strongly recommended for oligodendroglioma, WHO grade 3. A conditional recommendation for close surveillance alone was made for astrocytoma, IDH-mutant, WHO grade 2 after gross total resection without high-risk features. Adjuvant RT was conditionally recommended for astrocytoma, WHO grade 2, with any high-risk features and strongly recommended for astrocytoma, WHO grade 3. Dose recommendations varied based on histology and grade. Given known adverse long-term effects of RT, consideration for advanced techniques such as intensity modulated radiation therapy/volumetric modulated arc therapy or proton therapy were given as strong and conditional recommendations, respectively. Finally, based on expert opinion, the guideline recommends assessment, surveillance, and management for toxicity management.

CONCLUSIONS

Based on published data, the American Society for Radiation Oncology task force has proposed recommendations to inform the management of adults with IDH-mutant grade 2 and grade 3 diffuse glioma as defined by WHO 2021 classification, based on the highest quality published data, and best translated by our task force of subject matter experts.

The Misclassification of Diffuse Gliomas: Rates and Outcomes

PURPOSE

The integrated histopathologic and molecular diagnoses of the 2016 WHO classification of central nervous system tumors have revolutionized patient care by improving diagnostic accuracy and reproducibility; however, the frequency and consequences of misclassification of histologically diagnosed diffuse gliomas are unknown.

EXPERIMENTAL DESIGN

Patients with newly diagnosed ICD-O-3 (International Classification of Diseases) histologically encoded diffuse gliomas from 2010-2015 were identified from the National Cancer Database, the misclassification rates and overall survival (OS) of which were assessed by WHO grade and 1p/19q status. In addition, misclassification rates by isocitrate dehydrogenase (IDH), ATRX, and p53 statuses were examined in an analogous multi-institutional cohort of registry-encoded diffuse gliomas.

RESULTS

Of 74,718 patients with diffuse glioma, only 74.4% and 78.8% of molecularly characterized WHO grade II and III oligodendrogliomas were in fact 1p/19q-codeleted. In addition, 28.9% and 36.8% of histologically encoded grade II and III "oligoastrocytomas", and 6.3% and 8.8% of grade II and III astrocytomas had 1p/19q-codeletion, thus molecularly representing oligodendrogliomas if also IDH mutant. OS significantly depended on accurate WHO grading and 1p/19q status.

CONCLUSIONS

On the basis of 1p/19q, IDH, ATRX, and p53, the misclassification rates of histologically encoded oligodendrogliomas, astrocytomas, and glioblastomas are approximately 21%-35%, 6%-9%, and 9%, respectively; with significant clinical implications. Our findings suggest that when compared with historical histology-only classified data, in national registry, as well as, institutional databases, there is the potential for false-positive results in contemporary trials of molecularly classified diffuse gliomas, which could contribute to a seemingly positive phase II trial (based on historical comparison) failing at the phase III stage. Critically, findings from diffuse glioma clinical trials and historical cohorts using prior histology-only WHO schemes must be cautiously reinterpreted.