P14.98 Improving the targeting of Gamma-Knife radiosurgery for recurrent high-grade gliomas (WHO grades III and IV) with 11C-Methionine PET/CT

BACKGROUND

The survival of the patients with high-grade gliomas may be improved through a multidisciplinary approach including stereotactic re-irradiation such as Gamma-Knife at recurrence in a selected population. We report our experience in targeting the hypermetabolic areas of high-grade gliomas using 11C-Methionine PET/CT in selected patients.

MATERIAL AND METHODS

We retrospectively evaluated the local response in patients treated by Gamma-Knife for recurrent high-grade gliomas in our Institution between 2000 and 2018, targeting the hypermetabolic area with Methionine PET/CT.

RESULTS

We included 25 patients bearing high-grade gliomas (14 female, 11 male) with a median age of 45 years (5–64). There were 11 WHO grade III gliomas (6 astrocytomas, 5 oligodendrogliomas) and 14 glioblastomas. A total number of 33 Gamma-Knife procedures were performed. In all patients, the targeting was based on the hypermetabolic area as defined by Methionine PET/CT. Four patients were treated concomitantly on 2 or more targets. One patient was treated twice on different targets. We observed a positive response in 29 Gamma-Knife procedures, after a median interval of 2 months (1–33) and no response after 4 procedures (4 glioblastomas). In most cases, progression after Gamma-Knife was observed 4 months after irradiation.

CONCLUSION

Targeting the hypermetabolic areas with Methionine PET/CT was associated with favorable response in most patients treated by Gamma-Knife radiosurgery for local high-grade gliomas recurrence. Our results must be confirmed by a prospective study with regular and homogeneous morphological and metabolic monitoring.

[Contribution of temozolomide chemotherapy for intramedullary grade II spinal cord astrocytomas in adults: Our experience]

INTRODUCTION

Grade II intramedullary astrocytomas are rare tumors. Despite a well-defined role of adjuvant temozolomide chemotherapy for brain gliomas, the contribution of this therapy for intramedullary gliomas is not yet clearly defined.

METHOD

We retrospectively analyzed the data of 5 adult patients treated with temozolomide between 2008 and 2015 for a grade II intramedullary astrocytoma with progression after surgery.

RESULTS

Five patients from 19 to 70 years of age (median, 37years) underwent a second surgery for the progression of a grade II intramedullary astrocytoma (median progression-free survival 26months [8-90]). All tumors remained grade II. Due to a second clinical or/and radiological tumor progression, the patients were treated with temozolomide after a 37months median progression-free survival (5-66). All patients received at minimum 12 cycles (mean 14 ± 5; range 12-24) of temozolomide (150-200mg/m²/day, 5days/28days). All patients were alive after a 10-year median follow-up after diagnosis (6-13). All patients were able to walk except one, who was previously in McCormick autonomy grade IV before chemotherapy. The McCormick autonomy rating after temozolomide was stable for 4 patients and improved for 1 patient. The treatment was delayed once for hematological toxicity.

CONCLUSION

Temozolomide stabilized all 5 patients without any major toxicity. Based on this experience that needs to be confirmed, we consider that temozolomide should be envisaged within the therapeutic arsenal for progressive intramedullary grade II astrocytomas.