Intraoperative Radiotherapy After the Resection of Brain Metastases - a Phase II Feasibility Study

Brain metastases occur in up to 40% of all patients diagnosed with systemic cancer. Without adjuvant radiotherapy after resection of space occupying lesions local recurrence rates are high. That is why guidelines recommend a cavity boosting with x-rays. External beam radiotherapy can lower the risk of local recurrence but means longer hospitalization, prolongs the time to systemic salvage therapies and bears risks of radionecrosis and leucoencephalopathy with neurological and cognitive decline. A solution for this problem could be onetime intraoperative radiotherapy (IORT) with soft x-rays to sterilize the resection cavity, which may provide both: freedom from local recurrence fast track salvage therapy initiation.

INTRAMET is a single institution, open-label, prospective, phase 2 feasibility study for intraoperative radiotherapy immediately following resection of brain metastases. 50 adult patients with resectable not dural brain metastases should be treated in surgery after tumor resection with IORT with 20-30Gy prescribed to the margin of the resection cavity. The highest dose tolerable to surrounding risk structures (N. opticus, brainstem) should be used.

With this method, the investigators hope to show similar local control rates to postoperative external beam radiotherapy in line with guideline recommendations with less patient hospitalization and faster start of rescue therapies which could lead to a favorable overall outcome and less cognitive side effects.