Review Of Patients With Brain Metastasis Treated With Fractionated Stereotactic Radiation Therapy To Surgical Resection Cavity

Adjuvant whole brain irradiation following surgical resection is beneficial in controlling brain metastasis, though lacks survival benefit and there is concern for neurocognitive effect. This study evaluates the role of tumor bed fractionated stereotactic radiation therapy (FSRT) after resection of brain metastasis. This is a retrospective review of 30 patients who received FSRT from October 2009 to December 2011. Mean age is 61.4 years (33-83). Pathology of primary included melanoma (12), renal cell carcinoma (6), lung (4), breast and others (8). Eighteen patients (60%) had single brain metastasis. Complete resection was achieved in 28 patients (93.3%); two patients had resection of two metastatic lesions concurrently. Approximately 60% of the patients had controlled systemic disease at the time of irradiation. The majority of patients (90%) had Karnofsky performance status (KPS) ≥70 prior to irradiation (60-100). Planning target volume (PTV) was created by adding 2mm margin from resection cavity defined on post-operative MRI. Mean volume of PTV was 24.1cm3 (4.9-129). The median dose prescribed was 2500 cGy (2000-3000) in 5 daily fractions. Mean PTV coverage was 97.9% (93.9%-99.9%) and conformality index was 1.4 (1.1-2.4). Additional unresected metastases were treated with single fraction radiosurgery (SRS) in 10 patients and in one patient with FSRT concurrently with resection cavity FSRT. Median follow-up was 6 months (1.7-15). Forty percent of patients had progression of disease outside brain. Recurrences in brain were noticed locally in 4 (13%), distantly 12 (40%), combined 2 (7%). Mean progression free survival (PFS) was 5.7 months (1.6-15). While median local brain recurrence free survival (LBR-FS) was not reached, median distant brain recurrence free survival (DBR-FS) was 10.1 months. At 12 months, Local control at cavity is 87% and distant brain control is 57%. Log- rank showed statistically significant difference in DBR-FS by multiple brain metastases, progression of disease outside brain, and KPS<70; 3.93, 4.46 and 4.13 months, respectively. All patient tolerated radiation treatment and neurocognitive changes were not noted. One patient (3%) developed radiation necrosis which required surgical intervention. For those who recurred, 9 patients (30%) were salvaged by another modality. Out of 11 patients who received synchronous SRS/FSRT to metastatic sites, one recurred in SRS site locally (9.1%), one (9.1%) recurred locally in resection site and 8 patients had distant recurrences (72.7%). FSRT to surgical resection cavity of brain metastasis resulted in 12 months local control of 87%. The toxicity and side effects were minimal. Distant brain recurrence remains a major problem that may require further salvage therapy.