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About Brain Mets
Brain metastases (sometimes called brain mets) occur when cancer cells spread from their original site, in this case the lung, to the brain. Brain metastases may form one tumor or many tumors in the brain. As the metastatic brain tumors grow, they create pressure on parts of the brain and change the function of surrounding brain tissue. This can cause of a variety of symptoms. Sometimes brain mets are caught on a brain scan before they cause any symptoms.
Another type of brain mets is called leptomeningeal disease (LMD) which is when the cancer cells spread to the fluid around the brain instead of the brain tissue itself.
It is common for cancer cells to break off from the original tumor and travel through the bloodstream to other organs. In the case of lung cancer, one of the organs it most commonly travels to is the brain. The risk of lung cancer spreading to the brain is highest in small cell lung cancer and some specific forms of lung cancer like EGFR mutant or ALK rearranged lung cancer. If you have stage four lung cancer, your risk of brain metastasis is higher.
It varies a little by the type of lung cancer you have or the specific biomarkers in the cancer. Generally, brain metastases in lung cancer patients are very common. About 25% of lung cancer patients will have a brain met at diagnosis and there is a lifetime risk about 50%.
No. If the lesion is small, it could just be a blood vessel. If you have been treated with brain radiation in the past, it could be scarring or swelling from the treatment. Very rarely it could be a sign of another disease like multiple sclerosis, stroke or a parasite infection. Usually brain tissue is not biopsied. Instead, physicians look at how the lesion appears on the scan and use other clues like symptoms and information about the original cancer to determine if the lesion is likely cancer or not. Physicians also use brain scans taken over time as well as the patient’s health history to determine if a spot on the brain is likely cancer or not.
Symptoms & Diagnosis
Sometimes brain mets don’t cause any symptoms. Symptoms can either be focal (related to the specific part of the brain where there is a nodule) or they can be global (interfere with the general function of the brain). Focal symptoms are more likely to be like a stroke and may include slurred speech, blurry vision or limb weakness. Global symptoms are less specific and are likely to include headaches (especially in the morning after lying down all night) and confusion.
Other symptoms may include:
- Memory problems
- Change of personality
Sometimes symptoms can change rapidly if there is a bleed (hemorrhage) into a deposit in the brain. If this happens, your doctor may adjust any medications you are taking that could worsen the bleed. You may need neurosurgery to remove the blood. Even if there are no changes in symptoms, patients with hemorrhagic brain metastases are usually considered at higher risk for complications and should be monitored closely.
Leptomeningeal disease (LMD) can cause loss of balance, headache and occasionally pressure and loss of function in one of the nerves that supplies the head. LMD mostly produces global symptoms instead of focal symptoms.
It can be tricky to determine if your symptoms are related to brain mets or not. One indicator is if your symptoms come and go or if they are chronic. If you are experiencing a symptom that comes and goes, it is less likely to be related to cancer. Talk with your doctor about any symptoms you are experiencing.
Usually, brain mets are first diagnosed using an MRI with contrast. During an MRI with contrast, dye is injected into your arm which makes the image of the brain clearer.
After first diagnosis of brain mets, most patients get MRIs with contrast regularly. This could be every 6 weeks, eventually moving to every 3 months, but timing varies patient to patient. You will likely get more frequent scans at first and then when the scans show the treatment is working, you may go a longer stretch in between scans.
If a lung cancer patient doesn't have brain mets at first diagnosis, there is no clear guidance about how often a patient should receive an MRI to check for brain mets. However, for patients with stage four disease, most physicians will perform a yearly brain MRI.
LMD is usually diagnosed by lumbar puncture where a sample is taken from the fluid between two vertebrae in the lumbar (lower) part of the spine.
PET scans are not recommended for diagnosing or monitoring brain scans because the brain is very active and it makes the PET scan light up, even if there are no tumors.
Physicians have a choice between using a CT scan with contrast or an MRI with contrast. An MRI with contrast is preferred because it is a more sensitive test which can pick up smaller deposits in the brain. However sometimes availability and insurance coverage dictate whether or not a patient will receive a CT scan with contrast versus an MRI with contrast.
There are a variety of treatment options for lung cancer that has spread to the brain. Some medication you can take orally and will go through your blood stream to the brain. If you have certain biomarkers like EGFR, ALK or ROS1, a targeted pill that works on your lung cancer may also work on your brain lesions. However sometimes it can take several weeks to know if you have a biomarker that makes you eligible for a targeted pill. If your symptoms need to be addressed quickly, your doctor might consider steroids, focused radiation to the brain (see below) or even neurosurgery in rare cases.
The main way to treat lung cancer that has spread to the brain is through stereotactic brain radiation. There are two main types:
1. Focused radiation to the brain (also called stereotactic radiosurgery). This uses radiation beams in a very precise way to kill cancer cells in the brain. There are various machines that can do this for brain mets. Some examples include Gamma knife and Cyberknife.
2. Whole brain radiation therapy (WBRT). This type of radiation uses beams to treat the whole brain. Sometimes a technique called “hippocampal sparing” is used to block part of the brain from the radiation (the hippocampus) to prevent memory issues. Sometimes it is done to prevent brain mets in small cell lung cancer (SCLC) patients, who have a higher risk of brain mets and is called prophylactic cranial irradiation. Because of the side effects of WBRT, many physicians also consider watching the brain in small cell lung cancer closely with regular MRIs instead of prophylactic cranial irradiation.
LMD may be treated with targeted therapy pills, or chemotherapy, either injected through the arm, directly into the spinal fluid or through a device inserted under your scalp called an Ommaya reservoir.
Sometimes neurosurgeons remove a deposit in the brain, usually if it's large or causing many symptoms. Sometimes radiotherapy is given to the area where the tumor was removed after the surgery.
Proton therapy is a particular type of radiation originally developed for pediatric brain tumors that helps reduce long term side effects in children. In normal radiation therapy, there is a dose of radiation that is absorbed by healthy tissues after the radiation reaches the tumor. This is called the exit dose. With the use of proton therapy, protons enter the tumor and then stop, eliminating this exit dose and reducing damage to healthy tissue. Proton therapy is important in children but there is no data to support it is better than other forms of SRS in adults. With the increase of direct-to-consumer advertising of proton therapy, it is important to talk with your physician about your radiation treatment options before making any change to your treatment plan or treatment location.
Before you begin your treatment, you’ll have a treatment planning procedure called a simulation to prepare you for radiation. You will lie down on the table and your therapists will make you a mesh mask or a chin strap to help you stay in the correct position. Images will be taken of your head which are used to plan the angles and shapes of your radiation beams. You may also receive small tattoos or markings on your skin to guide the radiation therapists.
Your doctor will discuss anything you might need to do to prepare for the day of treatment. During brain radiation, you will be placed in the same position as when you had your simulation, and your radiation therapists will leave the room. Your radiation therapists will be able to hear and see you the whole time. You can breathe normally but try and stay still. If this concerns you, talk with your doctor about ways to help you stay calm.
There are possible side effects of brain radiation, but it is generally considered safe. Your body does not become radioactive after treatment, and it is safe for you to be around people afterwards.
Focused radiation has very little side effects as it is mostly killing tumor cells and not many normal cells. However, it is possible to have some swelling, called radiation necrosis, when the little rim of radiated normal cells around the tumor die off. Steroids and a drug called bevacizumab may be prescribed to help the swelling. In some cases, the inflammation needs to be surgically removed. Immunotherapy and some targeted drugs increase the rate of radiation necrosis. Symptoms of radiation necrosis are dependent on where it is in the brain but may include confusion, loss of movement and loss of speech. Radiation necrosis can occur months or even a few years after treatment.
Whole brain radiation therapy (WBRT) can cause fatigue in the short term and aging of the brain, including radiation dementia in the long term. A drug called memantine is sometimes used to reduce this risk, as well as the drug methylphenidate (known as Ritalin) if symptoms of slowed thinking occur.
It is possible to live well after brain radiation. The best things you can do are to try and keep your brain active with activities like reading, puzzles and conversations and to stay in close contact with your doctor about any side effects that you are experiencing.
Pseudoprogression generally refers to a lesion outside of your brain that gets bigger before it gets smaller while you are on immunotherapy. However, in relation to brain mets, radiation necrosis might also look like disease progression when it is just inflammation.
More important than finding a specialist who specializes in only a part of the body where a cancer spreads to, it is important to find a team that works together. Look for a care team where the medical oncologist who treats the lung cancer will work with the radiation oncology or neurological oncologist. Communication amongst team members about patient goals, expectations and side effect management is vital.
Page last updated: November 17, 2022