Prognostic factors for Brain Tumors
Besides the grades of CNS cancers/tumors, many factors have been identified which can predict the outlook of the CNS cancer/tumor. These factors are generally taken into account before starting the treatment of the disease. The prognostic factors for CNS cancers/tumors include-
- the type of cancer/tumor,
- extent of spread,
- patient’s age,
- patient’s performance status, etc
Read here about risk factors of brain tumors.
Brain Cancer Grading
Once the diagnosis of brain cancer is determined through various investigations, World Health Organization (WHO) grading system is the most widely used to describe the severity of CNS tumor based on the appearance of cancer cells under a microscope.
The cancer cells look like normal cells. These are typically slow-growing tumors that do not invade nearby brain tissue.
The cancer cells look like normal cells. These are slow-growing tumors that can involve nearby brain tissue and can transform to aggressive forms over time.
The cancer cells do not look like normal cells. These are fast-growing tumors that can involve nearby brain tissue and require intensive treatment.
The cancer cells do not look like normal cells. These are very aggressive and fast-growing tumors that can involve nearby brain tissue and require most intense treatment.
Brain Tumor Staging and Grading Investigations
Imaging tests are the mainstay of diagnosis for CNS tumors. These tests help in scanning the CNS and can accurately diagnose the location, size, and shape of the tumor. These tests play important role in defining the extent of disease. They are employed after treatment to evaluate the treatment efficacy and to detect any signs of disease progression/recurrence.
Magnetic resonance imaging (MRI) scan
This technique provides detailed images of internal body structures using radio waves, strong magnetic field, and gadolinium-based contrast material (which is used via intravenous injection to improve the clarity of the MRI images).
This is the most widely used technique for the diagnosis of CNS cancers/tumors because it can provide very detailed images of the brain and spinal cord tissue. Some more advanced MRI techniques are frequently used for the diagnosis of CNS cancers/tumors, which provide important information about the disease. Following are such techniques.
Magnetic resonance angiography (MRA) provides detailed images of the CNS vasculature and is very helpful in planning surgery.
Magnetic resonance spectroscopy (MRS) provides information about the composition in a particular area and can differentiate between the healthy and diseased tissue. It can further signal the type of defect in the suspected area.
Functional MRI (fMRI) highlights the slight change in blood flow in a particular part of the brain activated in real time. Thus, this technique is very helpful in mapping tumor-adjacent areas of the brain that are responsible for specific function, such as speech, though, movement, etc. This can be used for preserving important function by an appropriate planning of the indicated treatment (surgery or radiation).
Computed tomography (CT) scan
In this technique, detailed cross-sectional images of body organs are generated using x-rays with contrast agents. This technique can provide images of the CNS tumor. However, it is not primarily employed for the diagnosis of CNS tumors and is reserved for patients who cannot undergo MRI examination, such as those with an implanted pacemaker, metal fragment, paramagnetic surgical clips, extreme obesity, or those who have fear for closed spaces.
This technique can sometimes be used to highlight the CNS vasculature by CT angiography. Also, this technique can be used for determining the extent of disease and for planning the treatment in case radiation therapy is indicated for the treatment.
Biopsy samples contain a small number of cells or a tiny piece of tissue collected from the affected area with the help of a biopsy instrument. These samples are generally collected simultaneously with the main surgical procedure or sometimes before the main surgical procedure planned for the treatment of CNS tumor.
The collected biopsy sample is then tested in a laboratory and can help in establishing the diagnosis of CNS tumor based on the presence of characteristic cells.
In lumbar puncture, a sample of cerebrospinal fluid (CSF, a biological fluid that surrounds the brain and spinal cord) is collected with the help of a needle inserted up to the subarachnoid space around the spinal cord through the lower part (lumbar region) of the spine.
The collected sample is then analyzed in a laboratory for the presence of cancer cells (or tumor markers). This is generally employed for the CNS tumors that may spread via CSF or for primary CNS lymphomas. The detection of certain tumor markers in the CSF can establish the diagnosis of germ cell tumors. This technique can also be used to deliver a treatment into the CSF, if required.
Now let’s read about treatment of brain tumors.