Target volume delineation for radiotherapy of meningiomas: an ANOCEF consensus guideline

Lack of Impact of Expansion Size From Gross Tumor Volume to Planning Target Volume on Control Rates and Patterns of Recurrence in Fractionated Radiotherapy for WHO Grade 1 Meningiomas

OBJECTIVES

For single-fraction stereotactic radiosurgery (SRS) for WHO grade I meningiomas, no-GTV or minimal-GTV to PTV margin is an accepted practice. We evaluated whether there is a control difference based on GTV to PTV expansion size for fractionated RT.

METHODS

Eighty-seven patients with WHO grade 1 meningioma were identified from an institutional database, treated with either conventional immobilization and radiation treatment delivery techniques (cRT) with 5 to 20 mm PTV expansions or fractionated stereotactic radiotherapy (fSRT) with ≤3 mm GTV to PTV expansions. Kaplan-Meier estimators were used for local failure-free survival (LFFS), marginal-failure-free survival (MFFS), and distant failure-free survival (DFFS) analysis.

RESULTS

The median follow-up duration was 9.0 years. Twenty-five patients (29%) received cRT and 62 patients (71%) received fSRT. The median dose was 54 Gray. There were 4 local (5%), 1 marginal (1%), and 1 distant failure (1%). The fSRT and cRT groups each had 2 local failures; 3/4 local failures occurred in areas near critical organs at risk. For cRT versus fSRT, 5-year and 10-year LFFS were 100% versus 98% (P=0.46) and 94% versus 96% (P=0.34), 5-year and 10-year MFFS were 100% versus 100% and 100% versus 92% (P=0.004), and 5-year and 10-year DFFS were 100% versus 98% at both time points (P=0.65 and P=0.67, respectively).

CONCLUSIONS

In this patient cohort, there was no local control benefit for larger GTV-to-PTV expansions. For patients with tumors not eligible for SRS, fractionated stereotactic treatment workflow with ≤3 mm PTV expansions is an effective approach for WHO grade 1 meningiomas.

Early-Delayed Radiotoxicity Associated With Stereotactic Radiation Therapy Following a Daily 6 Gy × 5 (30 Gy) Protocol for Presumed Canine Intracranial Meningiomas

Early-delayed side effects (EDSEs) following treatment of canine intracranial meningiomas with 1-3-fraction stereotactic radiation therapy (SRT) can cause worsening neurologic signs, and one potential method of mitigating this toxicity is reducing the dose per fraction. Twenty dogs with imaging-diagnosed intracranial meningiomas and telephone follow-up of at least 6 months received a protocol of 6 Gy × 5, daily (30 Gy). A 'possible EDSE' was defined as mental dullness, neurologic exacerbation of existing neurologic signs or new neurologic signs occurring within 1-4 months of completing SRT, regardless of the response to steroids and even if an MRI was not performed. A 'probable EDSE' was defined as mental dullness, neurologic exacerbation of existing neurologic signs or new neurologic signs occurring within 1-4 months of completing SRT. These signs were either reversible with the initiation or increased doses of prednisolone, or follow-up MRI revealed no evidence of an alternate explanation. No dogs experienced acute radiotoxicity or clinical signs compatible with EDSEs. The protocol appears to result in limited acute radiotoxicity, and further evaluation of the frequency of long-term toxicities and relative efficacy should be undertaken.

Radioligand therapies in meningioma: Evidence and future directions

Meningiomas are the most common intracranial neoplasms in adults. While most meningiomas are cured by resection, further treatment by radiotherapy may be needed, particularly in WHO grades 2 and 3 tumors which have an increased risk of recurrence, even after conventional therapies. Still, there is an urgent need for novel therapeutic strategies after the exhaustion of local treatment approaches. Radionuclide therapies combine the specificity of tumor-specific antibodies or ligands with the cytotoxic activity of radioactive emitters. Alongside this, integrated molecular imaging allows for a noninvasive assessment of predictive biomarkers as treatment targets. Whereas the concept of "theranostics" has initially evolved in extracranial tumors such as thyroid diseases, neuroendocrine tumors, and prostate cancer, data from retrospective case series and early phase trials underscore the potential of this strategy in meningioma. This review aims to explore the available evidence of radionuclide treatments and ongoing clinical trial initiatives in meningioma. Moreover, we discuss optimal clinical trial design and future perspectives in the field, including compound- and host-specific determinants of the efficacy of "theranostic" treatment approaches.

Prognostic role of extent of resection and adjuvant radiotherapy in de novo anaplastic meningiomas

PURPOSE

Grade 3 meningiomas, although rare, are associated with high morbidity and mortality. The respective impacts of extent of surgical resection and adjuvant radiotherapy are still debated. Moreover, anaplastic meningiomas are studied in heterogenous cohort of de novo and progressive anaplastic tumors.

METHODS

We conducted a retrospective multicentric study on patients operated from a de novo anaplastic meningioma between 1999 and 2021. A centralized pathological review using 2016 WHO criteria was performed for all cases. Patients with history of radiotherapy or NF2-related Schwannomatosis were excluded.

RESULTS

Sixty-five patients were included in the study. Median progression free survival was 23 months and median overall survival was 2 years. Neither quality of resection nor adjuvant radiotherapy alone were predictive of better overall survival. Progression free survival were impacted by combination of gross-total resection and adjuvant radiotherapy (HR = 0.47 CI95% = [0.24-0.92], p = 0.027) and age at diagnosis (HR = 2.92 CI95% = [1.38-6.21], p = 0.005) in univariate analyses. Within anaplastic tumors, those graded on mitosis number had a poorer prognosis than those graded on overt anaplasia. Among anaplastic tumors with high mitotic score (> 20/10HPF), progression free survival were impacted by postoperative radiotherapy (HR = 0.44 CI95% = [0.22-0.88], p = 0.020) and gross total resection and adjuvant radiotherapy association (HR = 0.44 CI95% = [0.21-0.90], p = 0.024) in univariate analyses.

CONCLUSION

Simpson grade didn't show any impact on overall survival. Gross total resection + adjuvant radiotherapy favorably impacted progression free survival in our cohort of de novo anaplastic meningiomas.

Evidence-based clinical recommendations for hypofractionated radiotherapy: exploring efficacy and safety - Part 1. Brain and head and neck

Advances in radiotherapy (RT) techniques, including intensity-modulated RT and image-guided RT, have allowed hypofractionation, increasing the fraction size over the conventional dose of 1.8-2.0 Gy. Hypofractionation offers advantages such as shorter treatment times, improved compliance, and under specific conditions, particularly in tumors with a low α/β ratio, higher efficacy. It was initially explored for use in RT for prostate cancer and adjuvant RT for breast cancer, and its application has been extended to various other malignancies. Hypofractionated RT (HFRT) may also be effective in patients who are unable to undergo conventional treatment owing to poor performance status, comorbidities, or old age. The treatment of brain tumors with HFRT is relatively common because brain stereotactic radiosurgery has been performed for over two decades. However, re-irradiation of recurrent lesions and treatment of elderly or frail patients are areas under investigation. HFRT for head and neck cancer has not been widely used because of concerns regarding late toxicity. Thus, we aimed to provide a comprehensive summary of the current evidence for HFRT for brain tumors and head and neck cancer and to offer practical recommendations to clinicians faced with the challenge of choosing new treatment options.