Metastatic disease

The most common malignancy of the central nervous system (CNS) is metastatic disease,^18,31 accounting for approximately 20 per cent of clinically significant brain neoplasms.³⁷ CNS metastases affect more than 100 000 patients in the United States alone each year,³⁵ with an annual incidence of at least 11 individuals per 100 000 in the population.⁵⁸ In comparison to primary CNS tumours, metastases are approximately 3 times more common than glioblastoma (GBM) and more than 30 times more common than oligodendroglioma and ependymoma.⁶⁰ The incidence of CNS metastasis is increasing secondary to several factors, including the increasing incidence of lung cancer, the longer survival of cancer patients attributable to advances in treatment, and the increased sensitivity of metastasis detection by current magnetic resonance imaging (MRI). The resection of metastatic lesions is increasingly being incorporated as part of the treatment of cancer patients, even in patients with multiple CNS lesions, with the goal of increasing survival and controlling symptoms. Consequently, metastases are among the most common neuro-pathology specimens submitted to the anatomic pathology laboratory for the adult patient population.³