Description of the condition
The development of brain metastases is a frequent complication in people with cancer. In brain metastases cancer cells migrate from the place where they first formed (primary tumour) and travel, mainly through the blood, to the brain and form one or more tumours. Approximately 9.6% of all primary sites combined may spread to the brain during the course of the disease. Although many different malignant tumours have the ability to infiltrate the central nervous system, the most common primary tumours responsible for brain metastases are lung cancer (19.9%), breast cancer (5.1%), renal cell carcinoma (6.5%) and melanoma (6.9%). In contrast, other carcinomas, for instance prostate, oesophageal, oropharyngeal or non-melanoma skin cancers, rarely infiltrate the brain (Barnholtz-Sloan 2004; Bouffet 1997; Nayak 2012;Sundermeyer 2005). Brain metastases occur in more than 64% of people with lung cancer, and approximately 20% of those with breast cancer (Lassman 2003).
The haematogenous spread (when cancer cells are transported through the blood to distant sites of the body) is the most common mechanism of metastasis to the brain (Gavrilovic 2005) and as a consequence, the junction of the grey matter and white matter is the most frequent location, probably because blood vessels have a narrow diameter, acting as a trap for clumps of tumour cells (Delattre 1988).
Brain metastases, in the majority of cases, are multiple lesions that are diagnosed in later stages of the disease. However, in some cases brain metastases appear as the only deposit detected, either as a solitary brain metastasis, defined as “the only known metastasis of a tumour in the whole body which happens to be localised in the central nervous system” or as a single (also named singular) brain metastasis, defined as “a single cerebral metastasis with additional metastases in other organ systems” (Westphal 2003).
READ MORE: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD012086/full