How do you manage a recurrent brain metastasis in a surgical cavity that contains mixed radiation necrosis and viable tumor in the setting of prior SRS?

This diagnosis is made at our center by combining MRI, MR perfusion, and PET data.

Management depends on the presentation of the patient, if there is mass effect and/or neurological deficit then surgical re-resection is preferred. As a matter of interest, the pathology on the infrequent resections done in this setting (3 of ~500 patients a year in our practice) always shows a mix of necrosis and viable tumor. Re-resection seems to reduce the risk of steroid dependence in these patients as well.

If not symptomatic, we treat with 2 cycles of Bevacizumab and re-SRS. In this setting, we prefer hypofractionated (or multi-session SRS). Doses vary considerably 25 Gy in 5 Fxs is modal, but the prescription is very individualized and I am afraid emp...

In the setting of a region of the brain that has seen SRS, then surgical resection (for either tumor or necrosis), I would not personally recommend repeat SRS to the surgical cavity (which is now all or at least mostly normal brain that has already seen radiation). I do not think the risks of re-irradiation to a larger cavity assuming a GTR on MRI out weigh the benefits.

I would instead allow residual disease to declare itself and re-treat that in a salvage manner. We do post-op SRS in the unirradiated setting for a local control, not an OS benefit, compared to surveillance and treating at salvage.