Neurocognitive function after radiotherapy (RT) for supratentorial low-grade gliomas (LGG): results of a north central cancer treatment group (NCCTG) prospective study

Future Directions in the Treatment of Low-Grade Gliomas

ABSTRACT

There is major interest in deintensifying therapy for isocitrate dehydrogenase-mutant low-grade gliomas, including with single-agent cytostatic isocitrate dehydrogenase inhibitors. These efforts need head-to-head comparisons with proven modalities, such as chemoradiotherapy. Ongoing clinical trials now group tumors by intrinsic molecular subtype, rather than classic clinical risk factors. Advances in imaging, surgery, and radiotherapy have improved outcomes in low-grade gliomas. Emerging biomarkers, targeted therapies, immunotherapy, radionuclides, and novel medical devices are a promising frontier for future treatment. Diverse representation in glioma research and clinical trials will help to ensure that advancements in care are realized by all groups.

Postsurgical Approaches in Low-Grade Oligodendroglioma: Is Chemotherapy Alone Still an Option?

BACKGROUND

Patients with low-grade gliomas (LGGs) with isocitrate dehydrogenase (IDH) mutation (mut) and 1p19q codeletion (codel) have a median overall survival of longer than 10 years. The aim of this study is to assess the role of postsurgical treatments.

SUBJECTS, MATERIALS, AND METHODS

We evaluated patients with LGGs with IDH mut and 1p19q codel; IDH1/2 was performed by immunohistochemistry and quantitative polymerase chain reaction. In all wild-type cases, we performed next-generation sequencing. 1p19 codel analysis was performed by fluorescence in situ hybridization.

RESULTS

Among the 679 patients, 93 with LGGs with IDH mutation and 1p19q codel were included. Median follow-up (FU) was 96.1 months. Eighty-four patients (90.3%) were high risk according to Radiation Therapy Oncology Group criteria. After surgery, 50 patients (53.7%) received only FU, 17 (18.3%) chemotherapy (CT), and 26 (30.1%) radiotherapy (RT) with (RT + CT, 8 patients, 8.6%) or without (RT, 18 patients, 19.4%) chemotherapy. Median progression-free survival (mPFS) was 46.3 months, 50.8 months, 103.6 months, and 120.2 months in patients with FU alone, with CT alone, with RT alone, or with RT + CT, respectively. Median PFS was significantly longer in patients who received postsurgical treatment (79.5 months, 95% confidence interval [CI]: 66.4-92.7) than patients who received FU (46.3 months, 95% CI: 36.0-56.5). Moreover, mPFS was longer in patients who received RT (alone or in combination with CT, n = 26, 113.8 months, 95% CI: 57.2-170.5) than those who did not (n = 67, 47.3 months, 95% CI: 36.4-58.2). In particular, temozolomide alone did not improve PFS with respect to FU.

CONCLUSION

RT with or without chemotherapy, but not temozolomide alone, could extend PFS in IDH mut 1p19q codel LGGs.

IMPLICATIONS FOR PRACTICE

Low-grade gliomas with high-risk features, defined according to Radiation Therapy Oncology Group criteria, receive radiotherapy and/or chemotherapy as postsurgical treatments. Radiotherapy, however, has serious long-term effects (cognitive impairment), which are to be taken into account in these young patients. Moreover, low-grade gliomas with isocitrate dehydrogenase mutation and 1p19q codeletion (oligodendrogliomas) have an extremely long survival and a better prognosis. This study suggests that postsurgical treatments prolong the time before tumor progression in patients with good prognosis as well as those with oligodendroglioma. Moreover, temozolomide alone might not be effective in prolonging progression-free survival.

Cognitive Functions in Brain Tumor Patients

As effective treatment interventions have increased survival rates, there has been greater awareness that many brain tumor patients experience cognitive dysfunction despite adequate disease control. Cognitive difficulties often have an impact on quality of life and interfere with the patient's ability to function at premorbid levels; however, the incidence of cognitive dysfunction in brain tumor patients is unknown, because it has not been investigated systematically. Future prospective clinical trials in neuro-oncology should include cognitive outcome measures to increase understanding of the contribution of the tumor and the delayed effects of treatment to cognitive dysfunction.

Cognitive functions in low-grade gliomas: disease and treatment effects

BACKGROUND

The role of radiotherapy and chemotherapy in the treatment of low-grade gliomas (LGG) is controversial regarding their effect on survival and the development of neurotoxicity. The few published studies examining adverse treatment effects on cognition revealed conflicting results.

OBJECTIVE

To assess cognitive functioning in LGG patients who received conformal radiation therapy (RT), chemotherapy, or no treatment.

DESIGN

40 LGG patients participated in the study; 16 patients had RT +/- chemotherapy, and 24 patients had no treatment. All patients underwent a neuropsychological evaluation. APOE genotype was obtained in 36 patients who were classified in two groups based on the presence or absence of at least one apolipoprotein E small je, Ukrainian-4 (APOE small je, Ukrainian-4) allele.

RESULTS

Treated LGG patients had lower scores than untreated patients on several cognitive domains; patients who completed treatment at intervals greater than 3 years and had long disease duration had significantly lower scores on the Non-Verbal Memory domain. Antiepileptic polytherapy, treatment history, and disease duration jointly contributed to low Psychomotor domain scores. 62% of treated patients showed white matter confluence on MRI, whereas only 9% of the untreated patients had such changes. Preliminary comparisons between APOE small je, Ukrainian-4 carriers (n = 9) and non-carriers (n = 27) on cognitive domain scores revealed no statistically significant differences, but APOE small je, Ukrainian-4 carriers had lower mean scores on the Verbal Memory domain than did non-small je, Ukrainian-4 carriers.

CONCLUSIONS

RT +/- chemotherapy, disease duration, and antiepileptic treatment contributed to mild cognitive difficulties in LGG patients.

Low-grade gliomas: The debate continues

Low-grade gliomas (LGG) are a heterogeneous group of tumors that tend to occur primarily in young adults and children. They are indolent, progressive, and often undergo anaplastic transformation. The prognosis of these tumors is primarily affected by age and pathologic type. Many questions remain in the management of LGGs, including the role of surgical resection (ie, maximal tumor resection), the optimal timing of radiation (ie, postoperative vs at the time of tumor progression), and the role of chemotherapy (ie, salvage after radiotherapy, primary treatment after surgery, concurrent with radiotherapy). Further complicating treatment decisions are concerns about toxicity with any intervention because LGG patients can often lead a relatively normal existence for years with no intervention. In this article we review the pertinent LGG literature published over the past few years and its impact on the management of LGGs.

Long-term efficacy of early versus delayed radiotherapy for low-grade astrocytoma and oligodendroglioma in adults: the EORTC 22845 randomised trial

BACKGROUND

Postoperative policies of "wait-and-see" and radiotherapy for low-grade glioma are poorly defined. A trial in the mid 1980s established the radiation dose. In 1986 the EORTC Radiotherapy and Brain Tumor Groups initiated a prospective trial to compare early radiotherapy with delayed radiotherapy. An interim analysis has been reported. We now present the long-term results.

METHODS

After surgery, patients from 24 centres across Europe were randomly assigned to either early radiotherapy of 54 Gy in fractions of 1.8 Gy or deferred radiotherapy until the time of progression (control group). Patients with low-grade astrocytoma, oligodendroglioma, mixed oligoastrocytoma, and incompletely resected pilocytic astrocytoma, with a WHO performance status 0-2 were eligible. Analysis was by intention to treat, and primary endpoints were overall and progression-free survival.

FINDINGS

157 patients were assigned early radiotherapy, and 157 control. Median progression-free survival was 5.3 years in the early radiotherapy group and 3.4 years in the control group (hazard ratio 0.59, 95% CI 0.45-0.77; p<0.0001). However, overall survival was similar between groups: median survival in the radiotherapy group was 7.4 years compared with 7.2 years in the control group (hazard ratio 0.97, 95% CI 0.71-1.34; p=0.872). In the control group, 65% of patients received radiotherapy at progression. At 1 year, seizures were better controlled in the early radiotherapy group.

INTERPRETATION

Early radiotherapy after surgery lengthens the period without progression but does not affect overall survival. Because quality of life was not studied, it is not known whether time to progression reflects clinical deterioration. Radiotherapy could be deferred for patients with low-grade glioma who are in a good condition, provided they are carefully monitored.

Lessons learned from randomised clinical trials in adult low grade glioma

"Lesson" is a Middle English word that has been defined as "a passage from sacred writings read in a service of worship" as well as "something learned by study or experience". The term is quite appropriate in assessment of what has been learned from randomised trials in adult low-grade gliomas, since the treatment of these tumours has traditionally been guided as much by belief as by fact. Therefore, when assessing these trials we can apply the principles of hermeneutics. Thus, the first meaning of "lesson" given here can be described as literal, whereas the second may be seen as figurative. Since hermeneutics may also refer to an in-depth analysis of a particular text, the investigators will present their interpretation of data from randomised trials. The goal is to show that the lessons learned are not necessarily literal or dogmatic but can be much more allegorical in nature.

Cognitive sequelae of brain radiation in adults

Radiotherapy (RT) is a proven curative and palliative therapeutic tool in the treatment of a wide variety of primary and metastatic brain tumors in adults. Recent advances in multimodality therapy have led to improvement in survival for many cancer patients. As survival has improved, more attention has been directed toward long-term treatment-related morbidity. Specifically, the effect of RT on the long-term cognitive performance of these patients is a major concern. This article reviews the neurocognitive effects of cranial RT on adult patients with brain tumors. Analyses of neurocognitive function are confounded by factors such as surgery, chemotherapy, tumor characteristics, tumor progression, concurrent medical illnesses, neurologic comorbidity, and medications that can contribute to neurocognitive deficits. Risk of deficits after cranial RT is associated with high RT dose, large fraction size, larger field size, and extremes of age at time of treatment. Using modern techniques with moderate total doses (50 to 54 Gy), conformal RT, conventional fractionation, and advanced planning imaging and software, the risks of neurocognitive deficits are quite small and greatly overshadowed by deficits caused by the tumor itself. Further studies need to be undertaken to elucidate the degree and cause of cognitive decline in adult patients undergoing multimodality therapy for cranial tumors.