Top Line: Is pre-op stereotactic radiosurgery (SRS) an effective option for resectable brain metastases?
The Study: Post-operative SRS to brain metastasis resection cavities reduces the risk of local recurrence compared to surgery alone while reducing neurocognitive toxicity compared to whole brain radiation. However, post-op targets require additional margins that sometimes include the surgery tract. There is also concern about an increased risk of leptomeningeal disease (LMD) after brain met resection. Pre-operative, single fraction SRS may offer some appealing advantages. This retrospective cohort study analyzed 244 patients with 255 brain metastases treated with pre-op SRS at 5 institutions. Most patients had non-small cell lung cancer, breast cancer, or melanoma, and most had a single met. LINAC-based SRS was used in 89%, the median dose was 15 Gy x 1, and 66% had no PTV margin while 30% had a 1 mm margin. The median time from SRS to surgery was 1 day. After surgery, two patients (0.8%) were found to have non-metastatic lesions with both being GBMs. The cumulative incidence of local recurrence was 15% at 1 year and 18% at 2 years, which is comparable to that seen with post-op SRS. LMD developed in 6% at 1 year and 8% at 2 years. The rate of post-op complications was 7%. Any radiation related toxicity occurred in 7% with two patients eventually requiring surgery. Extent of resection was the strongest predictor of LR risk, which was 14% after gross total and 44% after subtotal resection.
TBL: Pre-op SRS for resectable brain metastases appears to have comparable control to post-op SRS with low toxicity and low rates of leptomeningeal recurrence. | Prabhu, Int J Radiat Oncol Biol Phys 2021