Medline ® Abstracts for References 1,3

PURPOSE: Population-based estimates of the incidence of brain metastases are not generally available. The purpose of this study was to calculate population-based incidence proportions (IPs) of brain metastases from single primary lung, melanoma, breast, renal, or colorectal cancer.

PATIENTS AND METHODS: Patients diagnosed with single primary lung, melanoma, breast, renal, or colorectal cancer (1973 to 2001) in the Metropolitan Detroit Cancer Surveillance System (MDCSS) were used for analysis. IP of brain metastases by primary site and variable of interest (race, sex, age at diagnosis of primary cancer, and Surveillance, Epidemiology, and End Results [SEER]stage of primary cancer) was calculated with 95% CIs.

RESULTS: Total IP percentage (IP%) of brain metastases was 9.6% for all primary sites combined, and highest for lung (19.9%), followed by melanoma (6.9%), renal (6.5%), breast (5.1%), and colorectal (1.8%) cancers. Racial differences were seen with African Americans demonstrating higher IP% of brain metastases compared with other racial groups for most primary sites. IP% was significantly higher for female patients with lung cancer, and significantly higher for male patients with melanoma. The highest IP% of brain metastases occurred at different ages at diagnoses: age 40 to 49 years for primary lung cancer; age 50 to 59 years for primary melanoma, renal, or colorectal cancers; and age 20 to 39 for primary breast cancer. IP% significantly increased as SEER stage of primary cancer advanced for all primary sites.

CONCLUSION: Total IP% of brain metastases was lower than previously reported, and it varied by primary site, race, sex, age at diagnosis of primary cancer, and SEER stage of primary cancer.

Central nervous system (CNS) metastasis was noted in 309 patients of 1044 autopsy cases of breast carcinoma. The brain was involved in 193 cases, and cranial dura in 167 cases. In 82 cases, the cranial dura was the sole site of CNS involvement. Metastasis to the leptomeninges was found in 59 cases, and to the spinal cord and dura in 32 cases. Metastases to the infratentorial portion of the brain was almost as frequent as to the cerebrum. Forty-two percent of the brain metastasis were single lesions, which is similar to the frequency of solitary metastasis to the brain from malignant tumors as a whole. CNS metastasis occurred more frequently in younger patients than older patients, and the clinical course of these patients was shorter than for those patients without CNS metastasis. CNS metastasis developed in the late stage of the disease, and often was not recognized clinically. Only 31% of the cases were clinically diagnosed or suspected before death. A median survival of these patients after clinical diagnosis of CNS metastasis was 33 days. However, a significant improvement was noted in the clinical diagnosis and median survival in the latter half of the study period. Eleven patients lived for more than 1 year after diagnosis of CNS metastasis. Only 14% of the 309 patients died from CNS failure.