Brain tumors: Clinical

Brain tumors are broadly classified into primary tumors originating from cells within the central nervous system, and metastatic tumors originating from cells outside the central nervous system.

Primary brain tumors are the most common solid tumors in children, while metastatic tumors are more common in adults.

The most common primary brain tumors in both adults and children are gliomas, a subset of these are called astrocytomas.

In adults, gliomas are followed by meningiomas, and in children, medulloblastomas and ependymomas are next on the list. These are followed by the less common schwannomas, oligodendrogliomas, craniopharyngioma, choroid plexus tumors, germinomas, hemangioblastomas, and primary central nervous system lymphoma.

Also, in children, most brain tumors are located below the cerebellar tentorium, or are infratentorial. Whereas in adults, most brain tumors are above it, or are supratentorial. Just remember that adults are taller than children.

Now, in order of decreasing frequency, metastatic brain tumors most commonly come from cancers of the lung, breast, and melanoma.

The main environmental risk factor for brain tumors is exposure to ionizing radiation, which can come from therapeutic radiotherapy for cancer, or diagnostic imaging like CT scans.

Electromagnetic radiation from cell phones and microwaves is currently being researched as potential risk factors in humans.

Immunocompromised people, like organ transplant recipients or individuals with AIDS are at high risk of primary central nervous system lymphoma caused by the Epstein-Barr virus, or EBV.

Meningiomas are particularly more common in women, possibly because the tumor cells possess estrogen and progesterone receptors.