Object. It has been suggested that synchronous brain metastases (that is, those occurring within 2 months of primary cancer diagnosis) are associated with a shorter survival time compared with metachronous lesions (those occurring more than 2 months after primary cancer diagnosis). In this study the authors used data obtained from the National Cancer Institute's Surveillance, Epidemiology, and End Results program to determine the incidence of synchronous brain metastases and length of survival of patients in a defined population of southeastern Michigan residents.
Methods. Data obtained in 2682 patients with synchronous brain metastases treated between 1973 and 1995 were reviewed. Study criteria included patients in whom at least one brain metastasis was diagnosed within 2 months of the diagnosis of primary cancer and those with an unknown primary source. The incidence per 100,000 population increased fivefold, from 0.69 in 1973 to 3.83 in 1995. The most frequent site for the primary cancer was the lung (75.4%). The second largest group (10.7%) consisted of patients in whom the primary site was unknown. The median length of survival was 3.2 months. There was no significant difference in the median survival of patients with primary lung/bronchus and those with an unknown primary site (3.3 months and 3.2 months, respectively).
Conclusions. Patients who present with synchronous lesions have a poor prognosis, and the predominant cause of death, in more than 90% of cases, is related to systemic disease; however, despite poor median survival times, certain patients will experience prolonged survival.