A brain tumor or brain tumour, is an intracranial solid neoplasm, a tumor within the brain.

Brain tumors include all tumors inside the human skull (cranium) or in the central spinal canal. They are created by an abnormal and uncontrolled cell division, usually in the brain itself, but also in lymphatic tissue, in blood vessels, in the cranial nerves, in the brain envelopes (meninges), skull, pituitary gland, or pineal gland.

Brain tumors show considerable phenotypic and genetic heterogeneity.

Primary and metastatic brain tumors comprise a heterogeneous group of CNS malignancies, varying in histological features ¹⁾ phenotypic presentation ²⁾ ,cell origin, and tumor grade as designated by the World Health Organization Classification of Tumors of the Central Nervous System.

Within the brain itself, the involved cells may be neurons or glial cells (which include astrocytes, oligodendrocytes, and ependymal cells). Brain tumors may also spread from cancers primarily located in other organs (metastatic tumors).

Adult Brain Tumors

Pediatric Brain Tumors

Each year, over 15 000 patients undergo resection of brain tumors in the United States ³⁾.

The facts and statistics include brain and central nervous system tumors (including spinal cord, pituitary and pineal gland tumors).

see The Central Brain Tumor Registry of the United States

The complex pathophysiology of brain tumor is dependent on various factors, including histology, molecular and chromosomal aberration, tumor-related protein expression, primary versus secondary origin, and host factors ^{4) 5) 6) 7)}.

20-40 % will have had a seizure.

Very few studies have utilized specific criteria to assess mental disorders in brain tumor patients, and from them, they are mainly descriptive.

Depression as well as anxious and OCD psychopathology were shown to be prevalent signs among patients with brain tumor. Diagnosis of symptoms were totally based on DSM-IV criteria and these disorders and the percentiles don't seem to be related to each other. Due to high variability of tumor stages, statistical analysis of whether the mentioned psychiatric symptoms get worsen at the later stages of the tumor genesis was not feasible. Although not measured directly, psychiatric symptoms seem to get worsen at the later stages of the brain tumor. The associated factors are tumor location, patient's premorbid psychiatric status, cognitive symptoms and adaptive or maladaptive response to stress ⁸⁾.

see Intracranial tumor diagnosis.

Robust methodology that allows objective, automated, and observer-independent measurements of brain tumor volume, especially after resection, is lacking.

The volumetric method had the strongest agreement with regard to radiological response (κ = 0.96) when compared with 2D (κ = 0.54) or 1D (κ = 0.46) methods ⁹⁾.

see Brain tumor treatment.