Types of cancer

Central Nervous System

Central nervous system tumor arises in the tissues of the brain and spinal cord. Unusual headache, epilepsy, and loss of motor functions are some of the symptoms. Malignant or metastatic tumors are usually fatal. Learn more.
7 min read
per: Grupo Oncoclínicas
Central Nervous System
Headache is the most common symptom of tumors located in the CNS. The others include epilepsy and loss of neurological function.

What is a Central Nervous System Tumor

The Central Nervous System (CNS) consists of the brain and spinal cord, and its tumors occur by the growth of abnormal cells in the tissues of these locations. About 88% of primary tumors of the Central Nervous System occur in the brain.

Primary CNS cancer accounts for 1.4% to 1.8% of all malignant tumors worldwide and is responsible for a disproportionate rate of morbidity and mortality.

Primary brain tumors, that is, those that originate in the brain, rarely spread to other parts of the body, but even those considered benign and indolent (slow-growing) can press into and destroy normal brain tissue, causing irreversible or even fatal neurological damage.

Central nervous system tumor subtypes

It is important to understand the difference between tumors that start in the brain (primary brain tumors) and tumors that start in other organs and have spread to the brain (secondary or metastatic). In adults, metastatic brain tumors are more frequent than primary brain tumors.

Primary CNS tumors comprise a wide range of pathological entities, each with a distinct natural history. For simplicity, CNS tumors can be classified as gliomas or non-gliomas. Currently, morphological and genetic features are found in each tumor type and assist in the proper diagnosis and classification of these tumor types.

The prognosis of patients with benign brain tumors is generally very favorable. Patients with malignant or metastatic primary brain tumors often die of the disease.

The main types of primary CNS tumors are:

  • Meningiomas – are usually benign and originate in the dura mater, the layer covering the brain and spinal cord. The incidence rate is approximately 2 cases per 100,000 individuals. They are more common in women in the sixth and seventh decades of life and are the most common primary brain tumors in adults. Many meningiomas are found incidentally on imaging exams and do not require treatment at the time of initial diagnosis. For patients with asymptomatic meningiomas, observation may be a management option. If a mass effect is seen in patients with or without symptoms, the treatment of choice is usually complete surgical resection. Radiation therapy can also be used as an isolated treatment or in addition to surgery for this type of tumor;
  • Pituitary Adenomas – pituitary tumors are typically functional or non-functional adenomas. Endocrine abnormalities can be found at presentation if the tumors are producing peptides such as prolactin, growth hormone, or adrenocorticotropic hormone;
  • Gliomas – are primary brain tumors originating from neuroglial stem cells or progenitor cells. Based on their histological appearance they have traditionally been classified as astrocytic, oligodendroglial, or ependymal tumors and classified between World Health Organization (WHO) grades I and IV, which indicate different degrees of malignancy;
  • Medulloblastomas – fast-growing tumors, considered grade IV by the WHO. They can be treated by surgery, radiotherapy, and chemotherapy. They are more common in children – their peak incidence occurs between 2 and 7 years of age – but young adults can also present them.

Symptoms and signs of central nervous system tumors

The symptoms of brain tumors can occur gradually, worsen over time, or appear suddenly. The presenting symptoms of a brain tumor are related to mass effect, infiltration of the parenchyma, and destruction of tissue. Headache, the most common symptom, is related to mass effects and occurs in approximately 35% of patients

Intracranial hypertension can be caused by tumor growth, edema in the brain, or blockage of cerebrospinal fluid (CSF) flow and lead to symptoms such as headache, nausea, vomiting, blurred vision, balance problems, changes in personality or behavior, seizures, and drowsiness.

There are three major groups of symptoms to look out for:

  • Headache with alarms: it is not just any ordinary headache that raises the suspicion of CNS tumors, only when it presents some alarm signal. These alarms are usually the emergence of a new headache (for those who have never experienced this type of pain), a change in the pattern of headache (for those who had pain before), worsening of the intensity (when it gets stronger over time), increased frequency (when the pain appears more often), or when the pain is fixed (every time it appears in the same place);
  • Epilepsy or other seizures: mainly when the patient presents with a seizure for the first time;
  • Loss of neurological functions: these are called focal deficits – when there is loss of strength or touch in the limbs, loss of vision or hearing, changes in speech or intellectual capacity (understanding, reasoning, writing, calculating, recognizing people), changes in behavior (apathy, agitation, or aggressiveness) from the person’s normal pattern.
  • The appearance of one or more of these changes should always be reported to the doctor and investigated appropriately.

Diagnosis

The patient’s anamnesis, history, and physical and neurological examination with alterations are the starting point for the suspicion of CNS tumors. In the face of clinical suspicion, complementary tests are performed in search of CNS neoplasms. The first are the imaging exams:

  • MRI – a diagnostic method that uses electromagnetic waves to form images. MRI produces images that make it possible to determine the size and location of a tumor, as well as the presence of metastases; and
  • Computed tomography – a diagnostic imaging technique that uses X-radiation to visualize small slices of body regions. It can be used in some cases where MRI is not a good option, such as for overweight patients or those who are claustrophobic. CT scans also provide better detail of the bone structures close to the tumor.

The lumbar puncture is used to diagnose cancerous cells in the cerebrospinal fluid (CSF), which bathes the spinal cord and brain. The procedure consists of aspirating CSF through a needle for later examination. This exam can help in the evaluation of licorice dissemination of some types of CNS tumors, such as medulloblastoma.

Blood and urine tests can also be performed. Although laboratory tests are rarely part of the diagnosis of brain and spinal cord tumors, they can be performed to check the function of other organs such as the liver and kidneys, especially if surgery and chemotherapy are scheduled.

Treatment

CNS tumors have a complex treatment that involves several different healthcare professionals.

It usually starts with the neurosurgeon, removing the tumor or a tissue fragment for biopsy. The next steps and the evolution will depend on the specific type of tumor, which is stated in the pathology report, involving the clinical oncologist, in the chemotherapy planning, and the radio-oncologist, in the radiotherapy planning.

Surgery on the brain and spinal cord tumors can be done to obtain a biopsy sample, to remove the tumor (or as much of it as possible), or to help prevent or treat symptoms or possible complications of the tumor.

Understand the treatment possibilities for CNS tumors below.

Surgery to remove the tumor

It is most often the first step in treating a brain or spinal cord tumor and is indicated as long as it is safe and does not affect normal brain function.

The goals of surgery are:

  • Diagnosis, providing tissue for histological and molecular analysis for proper tumor classification;
  • Reduce the mass effect, preserving the patient’s neurological function;
  • Promote cytoreduction, that is, reduction of the tumor size; and
  • Treat hydrocephalus, if present.

Advances in neuroanesthesia, micro neurosurgical techniques, and instrumentation have decreased the risk of surgery. When therapeutic intervention is deemed appropriate, surgery remains the initial therapy for almost all patients with brain tumors and can be curative for most benign tumors, including meningiomas.

Due to the infiltrative nature of most primary brain tumors, relief of mass effect and volume reduction results in symptomatic improvement and allows safe administration of complementary treatment with radiotherapy, whether or not associated with chemotherapy.

Radiotherapy

Radiotherapy is an essential component in the treatment of many patients with brain tumors. It can be curative for some patients and prolong survival the vast majority of the time it is applied.

It can be used in different situations:

  • After surgery, to kill any remaining tumor cells;
  • As the main treatment, if surgery is not a good option; and
  • In combination with chemotherapy; and
  • In some cases when the disease returns.

Chemotherapy

These are cancer drugs that can be administered intravenously or orally, and that enter the bloodstream and reach almost every area of the body. They help in the complementary treatment of CNS tumors associated with surgery, radiotherapy, or, in some cases, when used alone.

Targeted drugs

As researchers have learned more about the functioning of the cells that cause tumors or help tumor cells grow, new drugs have been developed that specifically target these changes. These are the target drugs, which, because they primarily attack the molecular features that exist in tumor cells, are generally less aggressive to normal cells and more effective against the tumor.

The drugs do not yet play a large role in the treatment of brain or spinal cord tumors, but some of them may be useful for certain types of tumors. 

It is now known that multimodal therapy with surgery, radiation therapy, and chemotherapy clearly reduces morbidity, prolongs survival, and may be curative in some patients. Given the limitations of current therapies, efforts to improve outcomes based on finding molecular targets present in the tumor are increasing.

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