Brain tumors and brain metastases

Overview: What are brain tumors and brain metastases?

A brain tumor is a tumor in the brain that can be either benign or malignant. There are many different types of brain tumors that arise from different cell types and tissues and can form in different places in the brain.

We distinguish between primary brain tumors that originate directly in the brain. They develop from the tissue of the brain or meninges and differ in their aggressiveness and malignancy. Brain metastases, on the other hand, are secondary brain tumors that are always malignant. They are caused by cancer of another organ. From there, the cancer cells spread to the brain and form cancer metastases. Many types of cancer such as breast cancer, lung cancer ormalignant melanoma can form such metastases in the brain.

Brain tumors can cause various symptoms, e.g. headaches. However, seizures(epilepsy), impaired consciousness, neurological problems or changes in character and personality can also indicate a tumor in the head.

The causes of primary brain tumors often remain unclear. We don’t know why one person gets it and the other doesn’t. Some risk factors can promote brain tumors. These include some rare hereditary diseases or undergoing radiotherapy due to a previous cancer. The cause of brain metastases, on the other hand, is a different cancer. Cancer cells spread from an organ to the brain via the blood and lymph channels and the cerebrospinal fluid. There they multiply.

The treatment of brain tumors always depends on the type of tumor as well as its location, size, spread and aggressiveness. There are various treatment options, which we often combine with each other. This makes the therapies more effective and powerful. For example, surgery, chemotherapy and radiation are used. In some types of brain tumors, targeted therapy or immunotherapy is also effective.

At what age do brain tumors occur?

Malignant brain tumors are rather rare compared to other types of cancer such as breast cancer, prostate cancer, lung cancer or colon cancer. They account for only around two percent of all cancers. In Switzerland, around 620 people are diagnosed with a malignant brain tumor every year.

At around 60 percent, men are affected slightly more often than women (40 percent). In principle, brain tumors can occur at any age, even in children. Around 25 percent of those affected are younger than 50 when they are diagnosed. There is also a peak incidence between the ages of 50 and 70.

Brain tumors and brain metastases: Causes and risk factors

The causes of brain tumors are still largely unknown. We assume that a brain tumor develops spontaneously and without any external cause or influence. A cancer (including a malignant brain tumor) always begins when the genetic material of a cell changes – it mutates. It can then divide and multiply unchecked. Cancer cells also have the ability to invade surrounding tissue and spread throughout the body via the blood and lymph channels and the cerebrospinal fluid. Benign cells, on the other hand, do not. However, benign tumors can still grow very large and displace and damage neighboring tissue.

We suspect that some risk factors are involved in the development of malignant brain tumors. In rare cases, for example, these include hereditary diseases caused by a genetic defect.

Previous radiotherapy of the brain due to cancer can also increase the risk of a brain tumor. In contrast to other cancers, lifestyle factors such as diet, alcohol or smoking do not play a role according to current knowledge. Environmental factors such as pollutants or chemicals are also unlikely to be involved in the development of the disease. Overall, the cause of the development of brain tumors is therefore unknown in most cases.

Brain metastases are caused by cancer of another organ, such as the breast, lungs or prostate. Metastases always mean that the cancer is already more advanced. The cancer cells then set off on a journey. Some types of cancer spread quickly, others do not. In some cases, we only discover the cancer when metastases have already formed, for example in the brain.

Symptoms of brain tumors and brain metastases

Benign and malignant brain tumors and brain metases can cause many different symptoms. Sometimes they cause headaches, but these can also have completely different (harmless) causes. There may also be many other symptoms, which are not specific to brain tumors and brain metases. They can also occur in many other neurological diseases. In particular, the symptoms depend on where in the brain the tumor is located and which centers are affected. Examples are:

• Nausea and vomiting
• Dizziness
• Seizures (epilepsy): Nerve cells “fire” and discharge uncontrollably. Especially in adults, a first seizure is an alarm signal.
• Impaired consciousness – from drowsiness to coma
• cognitive disorders, for example forgetfulness, impaired thinking, concentration and attention
• neurological disorders, for example paralysis, numbness, sensory disorders (e.g. heat, cold, touch, pressure), speech, vision, swallowing, movement and coordination disorders, gait instability, hearing loss
• Changes in character and personality, for example irritability, aggressiveness, listlessness, apathy, disorientation, anxiety, depression

If the tumor grows and spreads quickly, those affected will feel the first symptoms early on. However, some brain tumors grow slowly and only become noticeable after some time. Always seek medical advice if you experience such symptoms.

From the symptoms to the diagnosis of a brain tumor

The diagnosis of brain tumors and brain metastases always begins with a discussion of your medical history, the anamnesis. We ask you some questions, for example:

• What exactly are your symptoms?
• When did they first appear?
• How intense are the complaints?
• Are there times and situations in the daily routine when the symptoms improve or worsen?
• Have the symptoms changed over time, for example worsened continuously or improved again in between?
• Do you have any known pre-existing conditions? If yes: Which ones?
• Have you ever been diagnosed with cancer, if so, what type of cancer?
• Are hereditary diseases known in your family?
• Have you ever undergone cancer treatment in the past, for example radiotherapy?

This is followed by a physical and neurological examination. For example, we test reflexes and check the gait pattern, movement sequences, coordination and muscle function.

Other diagnostic methods and tumor types

Brain tumors and brain metastases: diagnosis using imaging techniques

Further information about the cause of the symptoms is provided by imaging procedures, for example:

• Magnetic resonance imaging (MRT or MRI = magnetic resonance imaging) – we use strong magnetic waves and obtain high-resolution cross-sectional images
• Magnetic resonance spectroscopy (MRS ): A special method that provides information on the condition of the brain tissue
• Computed tomography – an X-ray examination that produces detailed cross-sectional images of the head
• Positron emission tomography (PET): An examination method that can visualize areas in which the metabolism is particularly active. This is often the case with cancer cells. Sometimes we combine PET with CT or MRI (PET-CT or PET-MRI).

Brain tumors and brain metastases: further examinations

• Lumbar puncture: removal of cerebrospinal fluid (liquor) with a fine needle
• Electroencephalography (EEG ): We measure the brain waves and thus obtain indications of epilepsy.
• Tissue sample (biopsy): We take tissue from the suspected brain area. The type of cells (benign or malignant) can be determined under the microscope. We can also determine the type of tumor as well as its stage, spread and aggressiveness.

Brain tumors – classification according to WHO grades

The World Health Organization (WHO) divides brain tumors into four WHO grades. These allow conclusions to be drawn about the danger and the prognosis. The higher the grade (the number), the more aggressive the tumor and the less favorable the prognosis. The treatment strategy also depends on the WHO grade of a tumor.

• WHO grade I: It is a benign tumor that grows slowly and has a favorable prognosis.
• WHO grade II: The tumor is no longer benign and has a tendency to recur after treatment.
• WHO grade III: The tumor is malignant
• WHO grade IV: The tumor is very malignant, grows rapidly and has an unfavorable prognosis.

The WHO classification is revised regularly and only allows a very rough estimate of the prognosis of a particular tumor. In many cases, tumor tissue is now examined in detail in order to be able to make a more precise statement about growth behavior and prognosis based on certain (molecular) markers. Discuss these details with your doctor if necessary.

What types of brain tumors are there?

There are a number of different brain tumors that can be either benign or malignant. Some are initially benign and then develop into a malignant variant. Around 150 different brain tumors are known. They originate from different cell types and tissues in the brain. They also grow at different rates – some slowly, others aggressively and rapidly.

Many brain tumors (around 40 percent) originate in the supporting cells (glial cells). Such tumors are also called gliomas. This group includes, for example

• Glioblastomas – a very malignant tumor that originates from the astrocytes and behaves particularly aggressively. We therefore classify it as WHO grade IV. Glioblastoma accounts for around half of all gliomas.
• Astrocytomas: There are different types, which can be differentiated with a detailed tissue analysis. The origin lies in the astrocytes. Astrocytomas account for around 30 percent of all gliomas.
• Oligodendrogliomas (around eight percent of gliomas): They arise from the oligodendrocytes. There are different levels of danger.
• Ependymomas (about six percent) form from the covering tissue of the cerebral ventricle. They occur in different WHO grades.

There are many other types of brain tumors – the most important are

• MeningiomasThe origin lies in the membranes of the brain and spinal cord, the so-called meninges. Hence the name. In many cases, meningiomas are benign and grow slowly. However, there are also more dangerous variants.
• Medulloblastoma: Children and adolescents in particular suffer from this type of brain tumor, which is malignant. Medulloblastoma is an embryonal tumor and affects the cerebellum.
• Schwannomas (neurinomas) are benign tumors that originate from Schwann cells – they envelop the nerve fibers
• Neurofibromas also originate from Schwann cells and are benign. Compared to schwannomas, they have a different cell composition and a higher proportion of connective tissue.
• Pituitary adenomaThe origin lies in the glandular cells in the brain. The tumor is usually benign.
• CNS lymphoma – a malignant lymph gland tumor that affects the central nervous system (CNS).

Brain metastases are caused by cancer of another organ, such as the breast, lungs, skin or intestines. From there, the cancer cells spread throughout the body via the lymph and blood vessels – they can also reach the brain.

Prevention and early detection of brain tumors and brain metastases

The causes of brain tumors are not yet precisely known. Therefore, you cannot prevent the disease – whether benign or malignant. Even the few known risk factors such as previous radiotherapy or hereditary diseases cannot be addressed. Prevention is therefore not possible. You can also hardly protect yourself against brain metastases.

There are also no special measures in the doctor’s office for the early detection of brain tumors. If you suffer from a hereditary disease, you should have regular check-ups. Otherwise, the general advice is: always seek medical advice promptly if you experience symptoms such as severe headaches, dizziness, nausea and vomiting.

Targeted early detection of brain metastases is also not known. If you have already been diagnosed with cancer: Go for regular check-ups. Among other things, we look for signs of metastases. However, for certain types of cancer such as breast cancer or skin cancer, screening for early detection of cancer exists in many countries. Take advantage of these examinations, because in many cases we find cancer before brain metastases have formed.

Progression and prognosis of brain metastases and brain tumors

The course and prognosis of a brain tumor cannot be generally predicted. They vary from person to person and depend on several factors, for example:

• whether the tumor is benign or malignant,
• how aggressive it is and how fast it grows,
• how early we discover it and
• how big it is and what stage it is at.

The WHO grade determines the course and prognosis. The higher the grade, the faster the brain tumor grows and the more aggressive and dangerous it is. A tumor with WHO grade IV, for example, has an unfavorable prognosis if left untreated. Some tumors also tend to recur after treatment. We speak of a relapse or recurrence.

Even if the tumor is benign, it can still grow large and damage neighboring tissue. Depending on the location of the brain tumor, various brain functions may be impaired.

Brain metastases mean that the original cancer is already more advanced. In most cases, metastases are not only found in the brain, but often in other organs as well. Cancer at this stage is often no longer curable, but we can keep the metastases in check for a long time and slow down the progression of the disease.

Self-help groups

The exchange with people who are affected by the same disease can be a great support in coping with the disease. Advice on finding a suitable self-help group is available from Selbsthilfe Zürich. Self-Help Zurich and the University Hospital Zurich are cooperation partners in the national project “Health literacy thanks to self-help-friendly hospitals”.

Brain tumor: Therapy and treatments

At the University Hospital Zurich, we offer specialized treatment methods and therapies for patients with brain tumors and brain metastases. With targeted radiotherapy, we can treat both benign and malignant tumors in the brain and achieve a cure or prolong the life of those affected. Find out more about our detailed treatment procedures.