Primary Malignant Brain Tumors following Systemic Malignancies: A Population-Based Analysis

BACKGROUND: Several reports have described glioma following different cancers. We assessed the prevalence of primary malignant brain tumors afterward systemic malignancies in patients in the USA based on Surveillance, Epidemiology, and End Results (SEER) program data. METHODS: The detailed data of patients with primary malignant brain tumors following an initial malignant tumor outside the central nervous system were extracted from SEER. Descriptive statistics were used to analyze patient demographic and clinical characteristics. We also extracted standardized incidence ratios (SIRs) stratified by age, race, sex, history of radiation or chemotherapy, histology findings, and primary cancer site. RESULTS: We identified 5,212 patients diagnosed with primary malignant brain tumors following systemic malignancies. Most patients had prostate cancer, breast cancer, and skin melanoma as the primary cancer. The median duration between the first diagnosis of cancer and that of the subsequent malignant brain tumor was 53 months. Glioblastoma was the most common subsequent malignant brain tumor type. The prognosis after subsequent malignant brain tumor diagnosis was poor. The SIRs differed most by race, cancer site, and cancer type. Patients with acute lymphocytic leukemia had the highest risk of developing primary malignant brain tumors. CONCLUSION: Our study provides a comprehensive analysis of clinical data and the SIRs of patients with primary malignant brain tumors afterward other systemic malignancies. Genetic relationships might play a key role in subsequent malignant brain tumor origin. Our data provide directions for future studies exploring the hidden associations between systemic malignancies and primary malignant brain tumors.