Involved field radiation therapy after surgical resection of solitary brain metastases--mature results.

BACKGROUND: Whole brain radiation therapy (WBRT) reduces local recurrence in patients after surgical resection of brain metastases without improving overall survival. Involved field radiation therapy (IFRT) has been used at our center to avoid delayed neurotoxicity associated with WBRT in well-selected patients with surgically resected single brain metastases. The purpose of this study was to evaluate the long-term outcomes of these patients. METHODS: Thirty-three consecutive patients with single brain metastases from a known primary tumor were treated with gross total resection followed by IFRT between 2006 and 2011. The postoperative surgical bed was treated to 40.05 Gy in 15 fractions of 2.67 Gy with conformal radiation therapy. Patients received serial MRIs and neurological exams in follow-up. Surgery, WBRT, or stereotactic radiosurgery was performed as salvage treatment when necessary. RESULTS: The median follow-up was 16 months (range: 2-65 months). Local control, distant brain recurrence-free survival, and overall survival at 12 and 24 months were 90.3% and 85.8%, 60.7% and 51.4%, and 65.6% and 61.5%, respectively. Overall, 5 (15%) patients developed recurrence at the resection cavity, and 13 (39%) patients experienced recurrence at a new intracranial site. Two patients received WBRT, 8 stereotactic radiosurgery, 2 surgery, and 2 both chemotherapy and IFRT as salvage. Four patients died from CNS disease progression. CONCLUSION: For patients with newly diagnosed single brain metastases treated with surgical resection, postoperative IFRT to the resection cavity achieves reasonable rates of local control and is an excellent alternative to WBRT.