A prospective phase II trial on reirradiation of brain metastases with radiosurgery

In our previous published trial on radiosurgery (SRS) of recurrent brain metastases (BM) after whole brain radiotherapy (WBRT), Karnofsky performance status (KPS) and administered dose conditioned outcome and late toxicity, respectively. Brain radionecrosis was registered in 6% of patients. With the aim to obtain similar satisfactory outcomes and limit toxicity, we started a phase II trial in which reirradiation of BM with SRS were done using a tighter patient selection.

Patients with BM recurring after WBRT were recruited for reirradiation with SRS. Only patients with good KPS (≥70), good neurologic functional score (NFS 0-1) and lesions with a diameter ≤20 mm were considered eligible for retreatment. Dose exceeding 20 Gy was never administered.

The 59 patients reirradiated had 109 BM with a diameter range of 6-20 mm. Median interval between prior WBRT and SRS was 15 months and median SRS administered dose was 18 Gy (range 10-20 Gy). Complete and partial response (CR, PR) was obtained in 42% of patients with 2 years of control rate of 81%. Median overall survival (OS) after reirradiation was 14 months. No radionecrosis was detected.

Analysis of our current trial compared with results of our previous data suggests that a tighter patient selection (KPS ≥ 70; NFS 0-1, BM with ≤20 mm of diameter) and SRS dose ≤20 Gy allowed a high OS rate, a good percentage of CR and PR which last for >2 years, and no brain radionecrosis.