Resection Bed Radiosurgery Improves Local Control for Brain Metastases
Current management of brain metastases frequently involves stereotactic radiosurgery (SRS) and/or whole brain radiation therapy (WBRT) after surgery. This study examines factors associated with SRS to the surgical bed after brain metastasis resection. Overall, 86% of 120 patients achieved local tumor control with Gamma Knife SRS after initial gross total resection. Median marginal dose was 16.6 Gy with 55 months median follow-up. Tumor recurrences occur outside the planned treatment volume (PTV) at median 33 weeks. Margin dose less than 16 Gy significantly correlated with failure of local tumor control (p < 0.04), and PTV greater than 8.0 cm3 correlated with worse progression-free survival. No improvement in local control was observed in the 39% of patients who also received WBRT. In summary, SRS to the resection bed provides durable local control depending on PTV and margin dose > 16 Gy. Treating physicians should consider adding a margin up to 2 to 3 mm to the PTV for improved local tumor control.