title: Brain metastases in patients with no known primary tumor.
abstract: BACKGROUND
  The care of patients with a brain metastasis from unknown primary site is controversial. The authors reviewed the results of stereotactic radiosurgery in this group of patients to better define clinical expectations.
  
  
  METHODS
  During an 11-year interval, radiosurgery was performed in 421 patients with brain metastases at the University of Pittsburgh. Fifteen patients had solitary or multiple (< or = 5) brain metastases without a detectable primary site at the time of initial presentation. In five patients, a histologic diagnosis of cancer was obtained from extracranial metastatic sites. In 10 patients, a diagnosis was obtained from the brain. A total of 31 tumors with a mean volume of 4.3 mL (range, 0. 05-18.6 mL) underwent radiosurgery with a mean marginal dose of 16.2 Gray (Gy) (range, 12-20 Gy). Fourteen patients (93.3%) also received whole brain fractionated radiation therapy.
  
  
  RESULTS
  The median survival was 15 months after radiosurgery (range, 1-48 months) and 27 months after their initial diagnosis of cancer. In 4 patients (26. 7%), the primary tumor was discovered later (lung in 3 patients and liver in 1). Three of these four patients died due to progression of their primary tumor. Of the remaining 11 patients, 4 died of progression of extracranial metastases, 2 died of other systemic diseases, and 3 patients died because of progression of brain metastasis. Three patients (20%) were still living between 21-48 months after radiosurgery. The presence of active systemic disease and brain stem location both were associated with a poor outcome (P = 0.004 and 0.04). The actuarial imaging-defined local tumor control rate was 91.3 +/- 5.9% at 4 years.
  
  
  CONCLUSIONS
  Radiosurgery was an effective strategy for patients with brain metastases from an unknown primary site. Disease progression outside of the brain was the usual cause for patient death.
authors.affiliation: Department of Neurological Surgery, Center for Image-Guided Neurological Surgery, University of Pittsburgh, PA 15213, USA.
authors.forename: S
authors.initials: S
authors.lastname: Maesawa
authors.forename: D
authors.initials: D
authors.lastname: Kondziolka
authors.forename: T P
authors.initials: TP
authors.lastname: Thompson
authors.forename: J C
authors.initials: JC
authors.lastname: Flickinger
authors.forename: L
authors.initials: L
authors.lastname: Dade
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000401:mortality / Q000556:secondary* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009382:Neoplasms, Unknown Primary; D018579:Patient Selection; D016634:Radiosurgery; D016019:Survival Analysis; D016896:Treatment Outcome