Purpose: To better evaluate tumor control and toxicity from radiosurgery for brain metastases, we analyzed these outcomes in patients who had survived at least 1 year after radiosurgery.
Methods and materials: We evaluated the results of gamma knife stereotactic radiosurgery (SRS) for 208 brain metastases in 137 patients who were followed for a median of 18 months (range 12-122) after radiosurgery. The median patient age was 53 years (range 3-83). Ninety-nine patients had solitary metastases. Thirty-eight had multiple tumors. Sixty-nine patients underwent initial SRS with whole brain radiotherapy (WBRT), 39 had initial SRS alone, and 27 patients had failed prior WBRT. The median treatment volume was 1.9 cm(3) (range 0.05-21.2). The median marginal tumor dose was 16 Gy (range 12-25). The most common histologic types included non-small-cell lung cancer, breast cancer, melanoma, and renal cell carcinoma, which comprised 37.0%, 22.6%, 13.0%, and 9.13% of the lesions, respectively. Forty-five tumors were associated with extensive edema.
Results: At 1 and 5 years, the local tumor control rate was 89.6% +/- 2.1% and 62.8% +/- 6.9%, distal intracranial relapse occurred in 23% +/- 3.6% and 67.1% +/- 8.7%, and postradiosurgical sequelae developed in 2.8% +/- 1.2% and 11.4% +/- 3.5% of patients, respectively. Multivariate analysis found that local control decreased with tumor volume (p = 0.0002), SRS without WBRT (p = 0.008), and extensive edema (p = 0.024); distal intracranial recurrence correlated with younger patient age (p = 0.0018); and postradiosurgical sequelae increased with increasing tumor volume (p = 0.0085).
Conclusion: Long-term control of brain metastases and complication rates in this selective series of patients surviving >or=1 year after radiosurgery were similar to previously reported actuarial estimates. Large metastases and metastases associated with extensive edema can be difficult to control by radiosurgery, particularly without WBRT.