T2 FLAIR Hyperintensity Volume Is Associated With Cognitive Function and Quality of Life in Clinically Stable Patients With Lower Grade Gliomas

Cognitive reserve and individual differences in brain tumour patients

The aim of the paper is to determine the effects of the cognitive reserve on brain tumour patients' cognitive functions and, specifically, if cognitive reserve helps patients cope with the negative effects of brain tumours on their cognitive functions. We retrospectively studied a large sample of around 700 patients, diagnosed with a brain tumour. Each received an MRI brain examination and performed a battery of tests measuring their cognitive abilities before they underwent neurosurgery. To account for the complexity of cognitive reserve, we construct our cognitive reserve proxy by combining three predictors of patients' cognitive performance, namely, patients' education, occupation, and the environment where they live. Our statistical analysis controls for the type, side, site, and size of the lesion, for fluid intelligence quotient, and for age and gender, in order to tease out the effect of cognitive reserve on each of these tests. Clinical neurological variables have the expected effects on cognitive functions. We find a robust positive effect of cognitive reserve on patients' cognitive performance. Moreover, we find that cognitive reserve modulates the effects of the volume of the lesion: the additional negative impact of an increase in the tumour size on patients' performance is less severe for patients with higher cognitive reserve. We also find substantial differences in these effects depending on the cerebral hemisphere where the lesion occurred and on the cognitive function considered. For several of these functions, the positive effect of cognitive reserve is stronger for patients with lesions in the left hemisphere than for patients whose lesions are in the right hemisphere. The development of prevention strategies and personalized rehabilitation interventions will benefit from our contribution to understanding the role of cognitive reserve, in addition to that of neurological variables, as one of the factors determining the patients' individual differences in cognitive performance caused by brain tumours.

Adjuvant Chemoradiation Therapy Versus Chemotherapy Alone for Resected Oligodendroglioma: A Surveillance, Epidemiology and End Results (SEER) Analysis

OBJECTIVE

The benefit of postoperative adjuvant therapy for survival of oligodendrocyte glioma remains unclear. In this study, we compared the effect of chemoradiation therapy (CRT) and chemotherapy (CT) alone in patients who underwent resection. We aim to identify which adjuvant therapy provides more survival benefits.

METHODS

We identified patients who underwent oligodendroglioma resection in the Surveillance, Epidemiology and End Results (SEER) database. A multivariate Cox regression analysis was used to evaluate the factors affecting survival rates. We used a propensity matching analysis to minimize selection bias in each group. We performed subgroup analyses based on patients' clinical characteristics.

RESULTS

This study identified 1826 patients who received adjuvant CT (n = 503) or adjuvant CRT (n = 1323). On multivariate analysis, elderly, white and other race, and temporal lobe and parietal lobe tumor site were independent risk factors for improved overall survival (OS). After 1:1 propensity match, we included 501 patients who received CT and 501 with CRT. Patients in the CT group showed improved overall survival rate compared with those who received CRT (median OS: 146 months vs. 111 months). Subgroup analysis showed that improved overall survival in CT group was more significant in patients who were younger or older, male or female, white race, frontal lobe and parietal lobe tumor site, smaller tumor size (≤4 cm), and with gross total resection (GTR) (P < 0.05).

CONCLUSIONS

In patients with resected oligodendroglioma, adjuvant CT is associated with better survival compared to adjuvant CRT. The benefit was more significant in patients who were younger and older, male and female, white race, frontal lobe and parietal lobe tumor site, smaller tumor size (≤4 cm), and with GTR.

Current and Future Frontiers of Molecularly Defined Oligodendrogliomas

Oligodendrogliomas are a subtype of adult diffuse glioma characterized by their better responsiveness to systemic chemotherapy than other high-grade glial tumors. The World Health Organization (WHO) 2021 brain tumor classification highlighted defining molecular markers, including 1p19q codeletion and IDH mutations which have become key in diagnosing and treating oligodendrogliomas. The management for patients with oligodendrogliomas includes observation or surgical resection potentially followed by radiation and chemotherapy with PCV (Procarbazine, Lomustine, and Vincristine) or Temozolomide. However, most of the available research about oligodendrogliomas includes a mix of histologically and molecularly diagnosed tumors. Even data driving our current management guidelines are based on post-hoc subgroup analyses of the 1p19q codeleted population in landmark prospective trials. Therefore, the optimal treatment paradigm for molecularly defined oligodendrogliomas is incompletely understood. Many questions remain open, such as the optimal timing of radiation and chemotherapy, the response to different chemotherapeutic agents, or what genetic factors influence responsiveness to these agents. Ultimately, oligodendrogliomas are still incurable and new therapies, such as targeting IDH mutations, are necessary. In this opinion piece, we present relevant literature in the field, discuss current challenges, and propose some studies that we think are necessary to answer these critical questions.