Brain metastases as the only manifestation of an undetected primary tumor

BACKGROUND: The prognosis of patients with brain metastasis as the only manifestation of an undetected primary tumor generally is considered to be poor. Therefore, most treatment is palliative. The authors reviewed the clinical outcomes and treatment results of patients presenting with brain metastasis from an undetected primary tumor at The University of Texas M. D. Anderson Cancer Center. METHODS: Between 1977-1996, 220 patients were referred to the study department for the treatment of brain metastasis from an undetected primary tumor. The patients' records were reviewed to identify those for whom brain metastasis was the only manifestation of the primary tumor. The majority of patients were excluded from the current analysis because extracranial metastasis also were present. Thirty-nine patients qualified for this retrospective review. The level of neurosurgical excision varied, but all patients received radiotherapy. Tumor control in the brain and survival were analyzed by various tumor-related and treatment-related factors. RESULTS: In 31 patients, the brain metastasis were adenocarcinomas, whereas the remaining patients had tumors of various other histologies. In 12 patients, the primary tumor eventually was found, most commonly in the lung. The median survival time for all patients was 13.4 months. Overall survival rates (OS) at 1, 3, and 5 years were 56%, 19%, and 15%, respectively. Intracranial disease control was 72% at 5 years. Patients who received gross total resection (GTR) and radiotherapy had significantly better OS than patients who received radiotherapy alone. The OS of patients whose primary tumor was identified was similar to that of patients in whom the primary tumor remained occult. CONCLUSIONS: Brain metastasis as the only manifestation of an unknown primary tumor is a distinct clinical entity. The prognosis for patients with this presentation is better than that of patients with brain metastasis in general. Although the majority of patients die of extracranial disease, a few will achieve long term survival. Treatment to the brain is effective in controlling local disease; aggressive treatment with GTR and radiotherapy is recommended.