Reirradiation of brain metastases with radiosurgery

To assess the outcome of reirradiation with stereotactic radiosurgery (SRS) of brain metastases (BM) recurring after whole brain radiotherapy (WBRT).

Between September 2001 and October 2008, 69 patients who recurred after WBRT were re-irradiated with SRS using a linear accelerator. The dose prescription was generally chosen according to maximum diameter of the tumor as suggested by Radiation Therapy Oncology Group (RTOG) 90-05 protocol. Patients were stratified by Karnofsky Performance Status (KPS), Neurologic Functional Score (NFS), RTOG Recursive Partitioning Analysis (RPA), Score Index for Radiosurgery (SIR), primary disease, dimension and number of BM, and time to first brain recurrence after WBRT. Response, survival, and toxicity were analyzed.

At time of this retrospective analysis all patients had died. The 69 patients reirradiated with SRS had 150 metastases. Median interval between prior WBRT and SRS was 11 months and median SRS prescribed dose was 20 Gy. Response was obtained in 91% of lesions with 1-year local control rate of 74±4%. Significantly longer duration of response was associated with higher doses (≥23 Gy) and response achieved after SRS (complete and partial response better than stable disease). Cause of death was brain failure only in 36 (52%) patients. Median overall survival after reirradiation was 10 months. Variables which significantly conditioned survival were KPS and NFS. Four (6%) patients had asymptomatic radionecrosis that developed prevalently when lesion diameters were larger and cumulative doses exceeded the values recommended by RTOG 90-05 protocol. About three-fourth of the patients had a good KPS and NFS after reirradiation.

Reirradiation of BM with SRS resulted feasible and effective. A correct patient selection and an accurate evaluation of the cumulative irradiation dose were suggested.