Article
Intraoperative radiotherapy after the resection of brain metastases (INTRAMET) – protocol of a phase 2 feasibility study
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Published: | June 9, 2017 |
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Objective: 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 leucoencephalopathia 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.
Methods: We here introduce for the first time the study protocol of a single institution, open-label, prospective, phase 2 feasibility study for intraoperative radiotherapy immediately following resection of brain metastases. 50 adult patients with not before locally treated, 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.
Results: Primary endpoint will be local progression-free survival (PFS) of the treated metastasis. Secondary endpoints will be overall survival which will be differentiated between death related to global cancer progress and death from brain metastases. Further we will analyze the time to salvage cancer therapy, cognitive performance and the quality of life. Another secondary endpoint will be global and regional PFS to account for possible abscopal effects on the total cancer status and cancer status in the brain. Additional it should be proved that there are no dose limitation toxicities like wound healing disorders, cerebral hemorrhage or ischemia or radionecrosis with the need of surgical intervention.
Conclusion: With our new method we 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.