brain cancer Introduction
The brain is the body's command center and is roughly divided into three parts: the cerebrum, cerebellum, and brainstem.
Brain tumor
Benign brain tumor
Malignant brain tumor
It grows much faster and can damage and compress nearby normal brain tissue, affecting brain and body functions and even endangering life. This is what we often hear as "brain cancer".
Among benign brain tumors, pituitary tumors and meningiomas are the most common; while gliomas are the most common primary brain cancers.
iI. Introduction to brain tumors
Benign brain tumor
Slow growth rate
Good degree of differentiation
Slow symptoms
The tumor remained intracranial and rarely spread.
The chance of complete resection is high, and the chance of recurrence is low.
Malignant brain tumor
Fast growth rate
Poor degree of differentiation
Symptoms come quickly and severely
It may spread to other tissues, the spinal cord, or even other extracranial tissues and organs.
Difficult to completely remove, high chance of recurrence
Primary brain cancer and brain metastases
Primary brain cancer
Primary brain cancer refers to malignant tumors originating in the brain, generally named after the primary brain cells. The most common type is glioma, such as astrocytoma, which is formed by the lesion of astrocytic cells.
Vbrain metastasis
Brain metastasis refers to the spread of malignant tumors from other parts of the body to the brain via the bloodstream. Common cancers that cause brain metastasis include lung cancer and breast cancer. Brain metastasis is more common than primary brain cancer.
Risk factors for brain cancer
To date, the medical community does not fully understand the causes of brain cancer, but it may be related to the following risk factors:
Age: While people of any age can develop brain tumors, those over 40 years of age are at higher risk; however, some brain cancers, such as medulloblastoma, occur almost exclusively in children.
Family history：A family member has had glioma.
Long-term exposure to chemicals:long-term exposure to radiation, formaldehyde, vinyl chloride, and propylene, etc.
iII. Symptoms of brain cancer
Different areas of the brain have different functions, so a patient's symptoms are related to the location of the tumor. Some patients may be asymptomatic, with the tumor being discovered incidentally during a routine physical examination; others may experience more than one symptom simultaneously.
The symptoms of brain tumors can be divided into four categories：
Increased intracranial pressure
Clinically common symptoms of increased intracranial pressure are: headache, vomiting, visual impairment and consciousness impairment, etc.:
Headache:The headache is usually a dull ache; coughing, sneezing, and using the toilet can worsen it. Early headaches typically only occur upon waking in the morning; in later stages, the headaches become persistent and increasingly severe, and medication often fails to alleviate them.
Vomiting:Vomiting caused by brain cancer often comes on suddenly and violently, like "projectile vomiting," and is not necessarily accompanied by headache and nausea beforehand.
Visual impairment:Patients may experience blurred vision and double vision.
Impaired consciousness:This is caused by reduced blood flow to the brain and impaired brainstem function. If a brain tumor grows rapidly, it can cause cerebral edema, and the patient may go from being fully conscious to being in a coma in a short period of time.
Seizure
Endocrine disorders
Local neural dysfunction
Patients may experience focal neurological symptoms, such as weakness or clumsiness on one side of the body, abnormal sensation on one side of the body, unsteady gait, difficulty speaking, personality changes, visual field defects, and focal seizures.
iV. Types of brain cancer
Glioma
Astrocytoma (astrocytoma)
Patients may experience focal neurological symptoms, such as weakness or clumsiness on one side of the body, abnormal sensation on one side of the body, unsteady gait, difficulty speaking, personality changes, visual field defects, and focal seizures.
Oligodendrocyte glioma (oligodendorcyte)
Tumors that develop in dendritic glial cells are more common in the cerebral hemisphere and account for about 4% of primary brain tumors.
Ependymoma (ependymoma)
Tumors that occur in ependymal cells account for about 2% to 3% of all primary brain tumors.
Non-glioma
Meningioma (meningioma)
Tumors that develop in the meninges are typically formed by arachnoid cells, which are responsible for absorbing cerebrospinal fluid. Meningiomas account for approximately 13% to 30% of all brain tumors. Most meningiomas are benign; malignant meningiomas are very rare. The risk of developing a meningioma increases with age and is more common in women.
Medulloblastoma (medulloblastoma)
It is the most common malignant brain tumor in children, and it usually occurs in the posterior fossa—a specific area inside the skull (intracranial cavity) that contains the brainstem and cerebellum.
V. Diagnosis of brain cancer
Clinical physical examination
Imaging examination
Computerized Tomography (CT)： It is an advanced medical imaging technique that uses X-rays to scan the entire human body, producing multiple cross-sectional images. These images are then combined by a computer to create two-dimensional (2D) or even three-dimensional (3D) images, increasing the accuracy and efficiency of diagnosis. When performing a CT scan on a brain tumor patient, a medical contrast agent is used to make the images clearer. This examination involves a small amount of radiation.
Magnetic Resonance Imaging (MRI):Radiation-free, it can accurately display the detailed features of brain tumors and is an important diagnostic tool for brain tumors. It can also be used for preoperative assessment, helping with surgical localization and navigation.
Positron emission tomography-computed tomography (PET-CT)is an advanced isotope imaging technique that can display cellular metabolism and effectively assess the location and spread of tumors.
Pathological analysis
A surgical removal of a tissue sample from a brain tumor for pathological examination to determine its properties is known as a "tissue biopsy," and is the most accurate and reliable method for diagnosing brain cancer.
VI. Treatment of brain cancer
This section will focus on the treatment of glioblastoma multiforme (GBM).
Treatment options for GBM include surgery, radiation therapy, chemotherapy, targeted therapy, and the latest tumor-treating fields (TTFields) therapy. Doctors will develop a treatment plan based on each patient's individual circumstances. In most cases, more than one treatment method will be combined; for example, surgical removal of the tumor followed by radiation therapy or adjuvant drug therapy, to minimize the chance of recurrence.
Breast cancer ranks third among the top ten most common cancers in Hong Kong, and is the most common cancer among women. In 2018, there were over 4,600 new cases of breast cancer in Hong Kong. In addition to the increasing incidence rate year by year, breast cancer in Hong Kong is also showing a trend of affecting younger people. The median age at diagnosis for breast cancer patients in Hong Kong is 56 years old, and approximately 54% of breast cancer cases occur in women aged 40 to 59.
In recent years, significant progress has been made in the treatment of breast cancer. Patients who are diagnosed with breast cancer early and receive appropriate treatment immediately have a very high survival rate.
Surgery
Surgical treatment is the backbone of GBM, aiming to remove the tumor to the maximum extent possible without compromising vital brain functions. However, if the tumor invades, surrounds, or adheres to important brain tissue and nerves, the risks of surgery increase, and tumor removal becomes more difficult. Sometimes, after assessing the patient's condition, doctors may only be able to remove most of the tumor, while the remaining portion requires further removal using radiation and chemotherapy.
Craniotomy has made two major advances in the last decade:
Awake craniotomy: This means the surgery is performed while the patient is awake, allowing doctors to monitor important areas of the patient's brain in real time, avoiding damage to these areas during tumor removal that could affect the patient's future mobility and other bodily functions.
Fluorescent agentsBecause it is sometimes difficult to distinguish tumor cells from normal tissue with the naked eye, doctors use navigation systems and fluorescent agents to make tumor cells visible. This helps doctors clearly locate the boundaries of resectable tumors and remove them to the maximum extent possible without damaging important brain functions.
Radiotherapy
Radiation therapy (also known as electrotherapy) uses high-energy radiation to destroy cancer cells, preventing their proliferation and spread. In recent years, more advanced radiation therapy techniques include:
- Intensity-Modulated Radiation Therapy (IMRT)
- Image-Guided Radiation Therapy (IGRT)
- Digital navigation knife (Cyberknife)
- High-speed spiral radiation therapy (TomoTherapy)
- Proton Therapy (Proton Therapy)
Advanced radiotherapy techniques can increase radiation dose, effectively killing tumors while reducing damage to surrounding normal tissues.
Radiation therapy is usually performed after surgery and is sometimes used concurrently with chemotherapy. Its immediate risks are lower than those of surgery, but side effects are still possible, the most common being cerebral edema, hair loss, headache, nausea, vomiting, and skin redness.
Chemotherapy
Chemotherapy (also known as chemotherapy) uses anticancer drugs to destroy cancer cells. Temozolmide (TMZ) is a commonly used chemotherapy drug for brain cancer. TMZ can cross the blood-brain barrier (BBB) to reach the brain and destroy cancer cells. However, it may also damage normal cells in other parts of the body, causing side effects such as nausea, vomiting, hair loss, fatigue, and increased susceptibility to infection. Studies have shown that GBM patients who receive postoperative radiotherapy combined with TMZ have a significantly longer survival rate.
Many patients have heard about the side effects of chemotherapy, such as vomiting, diarrhea, hair loss, and fatigue, and are reluctant to undergo chemotherapy. However, various treatment options can cause different side effects, and the severity of the side effects varies from person to person. Before undergoing chemotherapy, patients can consult their doctors to understand the possible side effects and how to deal with them.
Chemotherapy is commonly used for small cell lung cancer that spreads rapidly. Doctors will develop one or more chemotherapy cycles based on the patient's condition, age, health status, and stage of cancer. Each cycle involves several days of chemotherapy, while the rest of the days are for the body to recover.
Common chemotherapy drugs for lung cancer can be categorized into platinum-based compounds, antimetabolites, vinca alkaloids, and paclitaxel. Platinum-based drugs are more likely to cause side effects in lung cancer patients, such as numbness and tingling in the hands and feet, which can potentially affect their daily lives. Although the side effects of chemotherapy may be more pronounced, most of them will gradually disappear after the chemotherapy course is completed.
In recent years, chemotherapy drugs have been continuously developed, and many new chemotherapy drugs can greatly reduce the side effects of treatment. Furthermore, chemotherapy's effectiveness in treating lung cancer is clearly evident. Lung cancer patients can consult their doctors before undergoing chemotherapy to understand how to reduce treatment side effects.
Targeted therapy
The commonly used targeted drug for treating GBM is bevacizumab, a monoclonal antibody that targets vascular endothelial growth factor (VEGF). It works by inhibiting tumor angiogenesis, thereby cutting off the nutrient supply to the tumor and suppressing its growth. The main side effect of bevacizumab is bleeding.
Tumor electric field therapy
TTFields is a novel cancer treatment technology. A clinical study in 2011 confirmed its efficacy against recurrent GBM, and another clinical study in 2015 confirmed that TTFields can effectively control newly diagnosed GBM. As a result, Hong Kong officially introduced TTFields in 2019.
The principle of TTFields is to deliver low-density, medium-frequency alternating tumor electric fields to the brain, which interferes with the normal division of cancer cells in the patient's brain, thereby slowing down the growth rate of cancer cells and causing them to die.
TTFields targets tumor division only and does not affect other normal brain tissues or their functions. Except for about 2% of patients who experience scalp itching or sensitivity due to prolonged use of the TTFields, there are no side effects during treatment.
How to use TTFields：
TTFields is a portable and wearable device. Patients need to attach four electrode patches to their scalp, connect them to a battery pack, and maintain them for at least 18 hours a day. The electrode patches need to be replaced every 2 to 3 days to achieve the therapeutic effect. Patients can continue their daily activities while using TTFields, such as eating, walking, and even exercising.
Timing of use of TTFields：
The U.S. Food and Drug Administration (FDA) and the European Union have approved TTFields for use in newly diagnosed GBM patients, in conjunction with the chemotherapy drug TMZ, after surgery and concurrent chemoradiotherapy. This indication has also been included in the National Comprehensive Cancer Network (NCCN) guidelines for GBM treatment.
Other drugs
The most commonly used treatments include antiepileptic drugs to control generalized or localized cramps, or steroids to reduce edema in tissues near the tumor.
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