Early vs. delayed radiotherapy in a small cohort of patients with supratentorial low grade glioma

The role of radiotherapy in the management of patients with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

QUESTIONS

(1) What is the optimal role of external beam radiotherapy in the management of adult patients with newly diagnosed low-grade glioma (LGG) in terms of improving outcome (i.e., survival, complications, seizure control or other reported outcomes of interest)? (2) Which radiation strategies (dose, timing, fractionation, stereotactic radiation, brachytherapy, chemotherapy) improve outcomes compared to standard external beam radiation therapy in the initial management of low grade gliomas in adults? (3) Do specific factors (e.g., age, volume, extent of resection, genetic subtype) identify subgroups with better outcomes following radiation therapy than the general population of adults with newly diagnosed low-grade gliomas?

TARGET POPULATION

These recommendations apply to adults with newly diagnosed diffuse LGG.

RECOMMENDATIONS

OUTCOMES IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA TREATED WITH RADIOTHERAPY: Level I Radiotherapy is recommended in the management of newly diagnosed low-grade glioma in adults to prolong progression free survival, irrespective of extent of resection. Level II Radiotherapy is recommended in the management of newly diagnosed low grade glioma in adults as an equivalent alternative to observation in preserving cognitive function, irrespective of extent of resection. Level III Radiotherapy is recommended in the management of newly diagnosed low grade glioma in adults to improve seizure control in patients with epilepsy and subtotal resection. Level III Radiotherapy is recommended in the management of newly diagnosed low-grade glioma in adults to prolong overall survival in patients with subtotal resection. Level III Consideration of the risk of radiation induced morbidity, including cognitive decline, imaging abnormalities, metabolic dysfunction and malignant transformation, is recommended when the delivery of radiotherapy is selected in the management of newly diagnosed low-grade glioma in adults. STRATEGIES OF RADIOTHERAPY IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA: Level I Lower dose radiotherapy is recommended as an equivalent alternative to higher dose immediate postoperative radiotherapy (45-50.4 vs. 59.4-64.8 Gy) in the management of newly diagnosed low-grade glioma in adults with reduced toxicity. Level III Delaying radiotherapy until recurrence or progression is recommended as an equivalent alternative to immediate postoperative radiotherapy in the management of newly diagnosed low-grade glioma in adults but may result in shorter time to progression. Level III The addition of chemotherapy to radiotherapy is not recommended over whole brain radiotherapy alone in the management of low-grade glioma, as it provides no additional survival benefit. Level III Limited-field radiotherapy is recommended over whole brain radiotherapy in the management of low-grade glioma. Level III Either stereotactic radiosurgery or brachytherapy are recommended as acceptable alternatives to external radiotherapy in selected patients. PROGNOSTIC FACTORS IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA TREATED WITH RADIOTHERAPY: Level II It is recommended that age greater than 40 years, astrocytic pathology, diameter greater than 6 cm, tumor crossing the midline and preoperative neurological deficit be considered as negative prognostic indicators when predicting overall survival in adult low grade glioma patients treated with radiotherapy. Level II It is recommended that smaller tumor size, extent of surgical resection and higher mini-mental status exam be considered as positive prognostic indicators when predicting overall survival and progression free survival in patients in adult low grade glioma patients treated with radiotherapy. Level III It is recommended that seizures at presentation, presence of oligodendroglial histological component and 1p19q deletion (along with additional relevant factors-see Table 1) be considered as positive prognostic indicators when predicting response to radiotherapy in adults with low grade gliomas. Level III It is recommended that increasing age, decreasing performance status, decreasing cognition, presence of astrocytic histological component (along with additional relevant factors (see Tables 1, 2) be considered as negative prognostic indicators when predicting response to radiotherapy.

Low-grade gliomas: an update on pathology and therapy

Low-grade gliomas (LGG) are not benign neoplasms. Patients with LGG eventually die as a consequence of this disease. Although the survival of patients with LGG is better than that of patients with higher-grade tumours, many of the treatments can produce or contribute to chronic impairment, particularly radiotherapy. Chemotherapy has emerged as a promising therapy, although definitive findings are awaited. Breakthroughs in molecular biology have improved our understanding of tumours and have led to the development of novel treatments and better prognoses. Ongoing clinical trials will help to elucidate the optimum management of patients with LGG.

Surgical resection for patients with benign primary brain tumors and low grade gliomas

'Benign' brain tumors are a heterogeneous group of primary neoplasms representing 40% of primary brain tumors. Amongst neuroepithelial tumors, astrocytic neoplasms predominate, followed by oligodendroglial and mixed glial and glial-neuronal neoplasms. Less common are tumors of the ependyma, choroid plexus and neuroepithelial tumors of unknown origin such as chordoid glioma of the third ventricle. Neurosurgical intervention is indicated in order to establish a diagnosis, alleviate symptoms of mass effect, hydrocephalus, or hemorrhage, remove a seizure focus and decrease the cell pool at risk of malignant degeneration. As the majority of patients survive their tumor for years after initial diagnosis, the benefits of therapy must be carefully weighed against adverse treatment effects. This article, with a particular focus on surgical management, reflects the authors approach to the treatment of low-grade tumors of the brain parenchyma in the adult and reviews the pertinent literature published on this controversial issue.

Does delay in starting treatment affect the outcomes of radiotherapy? A systematic review

PURPOSE

The objective of this study was to synthesize what is known about the relationship between delay in radiotherapy (RT) and the outcomes of RT.

METHODS

A systematic review of the world literature was conducted to identify studies that described the association between delay in RT and the probability of local control, metastasis, and/or survival. Studies were classified by clinical and methodologic criteria and their results were combined using a random-effects model.

RESULTS

A total of 46 relevant studies involving 15,782 patients met our minimum methodologic criteria of validity; most (42) were retrospective observational studies. Thirty-nine studies described rates of local recurrence, 21 studies described rates of distant metastasis, and 19 studies described survival. The relationship between delay and the outcomes of RT had been studied in diverse situations, but most frequently in breast cancer (21 studies) and head and neck cancer (12 studies). Combined analysis showed that the 5-year local recurrence rate (LRR) was significantly higher in patients treated with adjuvant RT for breast cancer more than 8 weeks after surgery than in those treated within 8 weeks of surgery (odds ratio [OR] = 1.62, 95% confidence interval [CI], 1.21 to 2.16). Combined analysis also showed that the LRR was significantly higher among patients who received postoperative RT for head and neck cancer more than 6 weeks after surgery than among those treated within 6 weeks of surgery (OR = 2.89; 95% CI, 1.60 to 5.21). There was little evidence about the impact of delay in RT on the risk of metastases or the probability of long-term survival in any situation.

CONCLUSION

Delay in the initiation of RT is associated with an increase [corrected] in LRR in breast cancer and head and neck cancer. Delays in starting RT should be as short as reasonably achievable.

Radiation therapy for incompletely resected supratentorial low-grade glioma in adults

In this review on current concepts in radiation therapy in the treatment of incompletely resected supratentorial low-grade glioma, a number of important issues are discussed. They include indication for radiation therapy, timing (early vs delayed), dose response issue, impact of modern neuroimaging, 'optimal' treatment fields, impact of histology, new and promising approaches as well as quality of life in this disease are also discussed. This disease remains a focus of investigations in neuro-oncology owing to the fact that a number of questions discussed in the text are still far from being optimally addressed and answers are, therefore, lacking. New studies and more patients are needed to get more insight into this disease.

Radiotherapy treatment planning and long-term follow-up with [(11)C]methionine PET in patients with low-grade astrocytoma

PURPOSE

To evaluate the feasibility of [(11)C]-methionine positron emission tomography (MET PET) in radiotherapy (RT) treatment planning and long-term follow-up in patients with low-grade glioma.

PATIENTS

Thirteen patients with low-grade astrocytoma and 1 with anaplastic astrocytoma underwent sequential MET PET and magnetic resonance imaging (MRI) before and 3, 6, 12, and 21-39 months after RT, respectively. Ten patients were studied after initial debulking surgery or biopsy and 4 in the recurrence phase.

METHODS

A total of 58 PET scans were performed. After transmission scanning, a median dose of 425 MBq of MET was injected intravenously and emission data was acquired 20 min after injection for 20 min. The uptake of MET in tumor area was measured as standardized uptake value (SUV) and tumor-to-contralateral brain SUV ratios were generated to assess irradiation effects on tumor metabolism. Functional imaging with PET was compared with concurrent MRI in designing the RT planning volumes and in assessment of response to RT during a median follow-up time of 33 months.

RESULTS

In 12 patients (86%), tumor area was clearly discernible in the baseline PET study. In the remaining 2 patients with a suspected residual tumor in MRI, PET showed only a diffuse uptake of MET interpreted as negative in the original tumor area. In the dose planning of RT, MET PET was helpful in outlining the gross tumor volume in 3 of 11 cases (27%), whereas PET findings either coincided with MRI (46%) or were less distinctive (27%) in other cases. In quantitative evaluation, patients with a low tumor SUV initially had significantly better prognosis than those with a high SUV. Tumor-to-contralateral brain uptake ratios of MET discriminated well patients remaining clinically stable from those who have since relapsed or died of disease.

CONCLUSION

Quantitative MET PET has prognostic value at the time of initial treatment planning of low-grade glioma. Some patients may benefit of RT volume definition with MET PET, which seems to disclose residual tumor better than MRI in selected cases. Stable or decreasing uptake of MET in tumor area after RT during follow-up seems to be a favorable sign.