J Clin Pathol 2005;58:237–242

“+ Many primary tumours metastasise to the brain, particularly those of the lung, breast, skin (melanoma), and gastrointestinal tract

+ Metastasis of cancer cells occurs via the ‘‘metastatic cascade’’, namely: invasion of surrounding tissue, entry into and survival in the bloodstream (intravasation), arrest and/or extravasation at the secondary site, and survival and proliferation

+ Developments in molecular biology have vastly expanded our knowledge about the mechanisms of invasion, proliferation, metastatic cell signalling, and angiogenesis in brain metastases, and several important
molecules involved in these processes have been identified, such as E-cadherin, catenins, neurotrophins, plasminogen activators and inhibitors and matrix metalloproteases

+ Recently, several metastasis suppressor genes (MSGs), which can spontaneously suppress metastatic growth at any point in the metastatic cascade, have been identified, such as nm23 and CD44

+ These advances in the understanding of the pathobiology of brain metastasis may lead to novel targeted treatment paradigms and a better prognosis for patients with brain metastatic disease”