General and more comprehensive text about cancer diseases, their behavior, causes and treatment can be found here.
In this article, I would like to write about brain tumors. Brain tumors can be dangerous and they are not as rare as it may seem. In the beginning, it is useful to differentiate the tumors:
Benign brain tumors vs. malignant tumors
Benign tumors grow and compress the area. They do not grow aggressively (i.e. they do not destroy surrounding brain tissue) and they do not form metastases. Malignant tumors behave oppositely by aggressively destroying the brain and forming brain metastases.
However, it should be noted that even benign brain tumors can easily kill the patient. The cranial cavity is an enclosed space and any growing lesion increases the intracranial pressure and can cause fatal brain damage. Therefore, the line between malignant and benign tumors is not as sharp and clear as in other organs of the body.
Primary brain tumors vs. secondary tumors
Primary brain tumors arise from the brain tissue (glioma, ependymoma, pituitary tumors, medulloblastoma, glioblastoma multiforme, etc.) or from its meninges (meningioma). Secondary brain tumors are actually brain metastases of malignant tumors of other organs. Brain is a relatively frequent target of metastases of breast cancer and melanoma, but many other cancers can metastasize into the brain.
The causes of brain tumors are usually unclear. There is probable some influence of genetic conditions as some brain tumors have reported familial occurrence and some are typical in certain genetic inherited disorders (such as neurofibromatosis). In addition, it is assumed that higher doses of radiation have relevance to a more frequent growth of brain tumors.
Brain tumors are relatively long asymptomatic, especially those benign. The most typical symptoms occur due to intracranial hypertension (headache, dizziness, vomiting, double vision, etc). Brain tumors are often associated with swelling of the brain. Benign tumors can irritate surrounding nerve cells, which can begin to create abnormal electrical impulses leading to epileptic seizures. This is indeed the reason, why every person after his or her first epileptic seizure should be properly examined, including the imaging methods of the brain. Malignant tumors directly destroy the surrounding neurons and thus cause blackouts of brain functions rather than epilepsy. The affected person may suffer from speech disorders, paralysis of muscles, local numbness and sensory disturbances. Brain tumors can also have influence on personality. They may cause changes of behavior and the whole personality, disruption of social habits, etc. Tumors of the pituitary gland (located in close proximity of the optic nerve) may cause visual disturbances with failure of the outer field of vision on both sides. The patient completely loses peripheral vision and further growth of the tumor can theoretically blind him totally. If a tumor is located near the olfactory nerve, the patient may experience impaired sense of smell.
Any patient with neurological disorders should be examined by a neurologist and when there is suspicion of an organic brain disease, the doctor should examine the patient by an imaging method such as computed tomography or magnetic resonance imaging.
The treatment is primarily surgical. Intracranial space and deeper areas of the brain are particularly difficult to access and complex neurosurgical operations are usually needed. However, some tumors may grow to large sizes and become inoperable.
Some hope for patients with primary and secondary brain tumors is the so-called Leksell gamma knife. There are only few hundreds of these special devices all over the world. The gamma knife emits a strong beam of radiation, which can be focused to a desired area. This area is destroyed with only a minimal damage to neighboring tissues. The main advantage is that the radiation acts from the outside and replaces the need of an invasive neurosurgical operation.
Classic radiotherapy and chemotherapy may be used as supportive methods of treatment, their effects are not very convincing in the therapy of brain tumors
In case of tumors increasing the intracranial pressure, it is wise to administer corticosteroids, which reduce the risk of cerebral edema. If the intracranial hypertension causes vomiting, antiemetic drugs can be used. Antiepileptic drugs are administered to prevent the tumor to cause recurrence of epileptic seizures.