Radiosurgery for brain metastases from unknown primary cancers.

We evaluated the role of Gamma Knife stereotactic radiosurgery in the multidisciplinary management of brain metastases from an undiagnosed primary cancer.Twenty-nine patients who had solitary or multiple brain metastases without a detectable primary site underwent stereotactic radiosurgery between January 1990 and March 2007 at the University of Pittsburgh. The median patient age was 61.7 years (range, 37.9-78.7 years). The median target volume was 1.0 cc (range, 0.02-23.6 cc), and the median margin radiosurgical dose was 16 Gy (range, 20-70 Gy).After radiosurgery, the local tumor control rate was 88.5%. Twenty four patients died and 5 patients were living at the time of this analysis. The overall median survival was 12 months. Actuarial survival rates from stereotactic radiosurgery at 1 and 2 years were 57.2% and 36.8%, respectively. Factors associated with poor progression-free survival included large tumor volume (3 cc or more) and brainstem tumor location.Radiosurgery is an effective and safe minimally invasive option for patients with brain metastases from an unknown primary site.