Early Stereotactic Gamma Knife Radiosurgery to Residual Tumor After Surgery of Newly Diagnosed Glioblastoma (Gamma-GBM)

Early Stereotactic Gamma Knife Radiosurgery to Residual Tumor After Surgery of Newly Diagnosed Glioblastoma

Early Stereotactic Gamma Knife Radiosurgery to Residual Tumor After Surgery of Newly Diagnosed Glioblastoma

Gamma GBM is a single-arm phase II trial that prospectively measures the progression-free survival time after addition of an early gamma knife boost to areas of residual tumor to standard-of-care (surgery, chemo-radiotherapy, chemotherapy).

Glioblastomas are highly malignant brain tumors that recur about 6 months after treatment. Most recurrences develop at the edge of the surgical margin and a common reason for an early recurrence of a glioblastoma is when tumors are not completely resected. This may be the case when intraoperative neuro-monitoring indicates that further resection would impair certain motor functions. Physicians can identify residual tumor in early (24-72h after surgery) postoperative MRI scans and could treat these regions. However, this treatment would not be a part of the recommended standard of care and thus, any further treatment of this areas will need a clinical trial. The aim of this trial is to evaluate if the use of another modality to deplete these areas of residual tumor identified in early postoperative MRI scans will provide a relevant benefit in terms of progression-free survival (which means a prolongation of the time that patients do not experience a re-growth of the tumor). The modality is termed "radiosurgery", which is a non-invasive technique to delete cells without using a blade but a highly focused beam of gamma rays. The machine that focusses these rays (like a magnifying glass that can focus light), is called 'gamma knife'. Gamma knife radiosurgery is a safe and effective treatment for a plethora of malignant and benign brain tumors and the technique is used since the 1950s and there has been a continuous improvement of precision and patient comfort up to now.

Following intraoperative confirmation of glioblastoma (frozen section): Early (24-72h post surgery) stereotactic ablation (gamma knife radiosurgery) of residual tumor (defined in early postoperative T1-weighted MRI scanning with and without contrast), followed by standard-of-care therapy (chemo-radiotherapy with 60 Gy external beam radiation therapy (EBRT) and 75 mg/m2/d temozolomide, followed by adjuvant chemotherapy with 150-200 mg/m2/d/cycle temozolomide in a 5/28 days schedule).

Radiosurgery with a gamma knife resembles the application of a precisely focused, high single dose of ionizing irradiation.

PFS is defined as the time span of initial diagnosis (i.e., the day of surgery) until tumor progression is confirmed in follow-up MRI scans. All scans will be assessed using modified Response Assessment in Neuro-Oncology (RANO) criteria or until death by any cause.

OS is defined as the time span of initial diagnosis (i.e., the day of surgery) until death by any cause.

Inclusion Criteria: Age ≥ 18 Karnofsky performance status score ≥ 60 histology must be glioblastoma (frozen sections during surgery) radiographic proof of residual tumor Informed consent adequate birth control (e.g., oral contraceptives) Exclusion Criteria: any previous cranial radiotherapy histology inconclusive or low(er)-grade astrocytoma contraindications for chemo- or radiotherapy bleeding or clotting disorders contraindications for MRI or CT scans