What data is there for using SRS to treat more than 3 lesions?

The short answer to this is that there are no randomized trials supporting SRS alone for more than 4 lesions, in comparison to SRS and whole brain radiotherapy, or whole brain radiotherapy alone. This does not mean that SRS alone is contraindicated, and I believe that SRS alone can be used as up front therapy for patients with 5 or more brain metastases, but selecting the appropriate patient is key.

I believe the appropriate patient for radiosurgery alone for 5 or more brain metastases are those with

1. A good performance status
2. Reasonable likelihood of prolonged extracranial disease control
3. Are open to frequent MRI surveillance and are motivated to maximize neuropreservation.

Multiple (albeit retrospective) pooled and single institution st...