Lung Cancer Metastasis to Brain: Understanding Symptoms, Treatment, and Prognosis
What is lung-brain metastasis?
Lung cancer metastasis to brain, including symptoms, treatment options, and prognosis – discover. Find coping strategies and prevention tips.
Brain metastasis, also known as brain mets, happens when cancer cells from the lung spread to the brain. They can form one or multiple tumors in the brain. As these tumors grow, they put pressure on the brain and affect its functioning, leading to various symptoms. Sometimes, brain mets are detected through brain scans before any symptoms show up.
Why does lung cancer spread to the brain?
Another type of brain mets is called leptomeningeal disease (LMD). Instead of spreading to the brain tissue, cancer cells in LMD spread to the fluid around the brain. It is common for cancer cells to break away from the original tumor and travel through the bloodstream to other organs.
In the case of lung cancer, the brain is one of the organs it commonly spreads to. The risk of lung cancer spreading to the brain is higher in small cell lung cancer and specific forms of lung cancer such as EGFR mutant or ALK-rearranged lung cancer. If you have stage four lung cancer, your risk of brain metastasis is higher, but it can vary depending on the type of lung cancer or specific biomarkers in the cancer.
How common are brain metastases in lung cancer patients?
Generally, brain metastases are quite common among lung cancer patients. About 25% of lung cancer patients will have brain mets at the time of diagnosis, and the lifetime risk is around 50%.
Are all spots or ‘lesions’ found on a brain scan considered metastasis?
Sometimes, when a small lesion is found, it might not be cancer but could be a blood vessel. If you have received brain radiation treatment in the past, it could be scarring or swelling caused by the treatment. In rare cases, it could be a sign of another disease like multiple sclerosis, stroke, or a parasite infection. Usually, doctors don’t perform a biopsy on brain tissue. Instead, they examine how the lesion appears on the scan and consider symptoms and information about original cancer to determine if it is likely cancer or not. Doctors also analyze brain scans taken over time and consider the patient’s health history to determine if a spot on the brain is likely cancer or not.
What are the symptoms of brain metastasis?
Sometimes brain mets don’t cause any problems that you can notice. Symptoms can either affect a specific part of the brain or interfere with how the whole brain works. Symptoms that affect a specific region are more like a stroke and can include problems like slurred speech, blurry vision, or weakness in your limbs. Symptoms that affect the whole brain are less specific and can include headaches (especially in the morning after sleeping all night) and feeling confused.
Other symptoms can include:
- Trouble remembering things
- Feeling unsteady
- Changes in your personality
- Having seizures
Sometimes, if there is bleeding in the brain from a tumor, symptoms can change quickly. If this happens, your doctor may adjust the medications you’re taking to make sure the bleeding doesn’t get worse. You may need to have surgery to remove the blood. Even if your symptoms don’t change, having bleeding in the brain from metastases means you’re at higher risk for complications, so you’ll be closely watched.
Leptomeningeal disease (LMD) can cause problems with your balance, headaches, and sometimes pressure and loss of function in one of the nerves that go to your head. LMD mostly causes general problems instead of specific ones.
It can be hard to know if your symptoms are from brain mets or something else. One thing to think about is whether your symptoms come and go or if they are always there. If your symptoms come and go, they’re less likely to be from cancer. Talk to your doctor about any symptoms you have.
How is brain metastasis diagnosed?
Usually, doctors use an MRI with a special dye to diagnose brain mets. The dye is injected into your arm and helps make the picture of your brain clearer.
After you’re first diagnosed with brain mets, you’ll usually get regular MRIs with the dye. This might be every 6 weeks at first, and then maybe every 3 months, but it depends on each person. At first, you might get scans more often, but as the scans show that the treatment is working, you might have them less often.
If you don’t have brain mets when you’re first diagnosed with lung cancer, there isn’t a clear guideline for how often you should get an MRI to check for them. But if you have stage four cancer, most doctors will do an MRI of your brain once a year.
What is the logic behind the different types of scans for brain metastases?
To diagnose LMD, doctors usually do a test called a lumbar puncture. They take a sample of the fluid between the lower part of your spine to check for cancer cells. PET scans aren’t recommended for diagnosing or watching brain mets because the brain is very active and the scan can look abnormal even if there aren’t any tumors.
Doctors can use either a CT scan or an MRI with a special dye to look for brain mets. An MRI is usually better because it can find smaller tumors. But sometimes, depending on what’s available and what your insurance covers, you might have a CT scan instead of an MRI.
What treatments are available for lung cancer that has spread to the brain?
When lung cancer spreads to the brain, there are different ways to treat it. You can take medications by mouth that travel through your bloodstream and reach the brain. If you have specific biomarkers like EGFR, ALK, or ROS1, a targeted pill that works on your lung cancer may also work on brain tumors. But sometimes it takes a few weeks to find out if you have the right biomarkers for this treatment. If you need to address your symptoms quickly, your doctor might suggest steroids, focused radiation to the brain, or in rare cases, neurosurgery.
The main treatment for lung cancer that has spread to the brain is called stereotactic brain radiation. There are two main types:
- Focused radiation to the brain: This uses precise radiation beams to kill cancer cells in the brain. There are different machines that can do this, like the Gamma Knife and CyberKnife.
- Whole brain radiation therapy (WBRT): This type of radiation treats the entire brain with beams. Sometimes, doctors use a technique called “hippocampal sparing” to protect the memory center of the brain (the hippocampus) from radiation and prevent memory issues. In some cases of small cell lung cancer (SCLC), where there is a higher risk of brain metastases, prophylactic cranial irradiation (radiation to the brain to prevent metastases) may be considered. However, due to the side effects of WBRT, many doctors prefer regular brain scans (MRIs) to watch for any new metastases in SCLC patients instead of prophylactic cranial irradiation.
For leptomeningeal disease (LMD), targeted therapy pills or chemotherapy can be used. Chemotherapy can be given through an injection in your arm, directly into the fluid around your spinal cord, or through a device called an Ommaya reservoir that is placed under your scalp.
Sometimes, if a tumor in the brain is large or causes significant symptoms, neurosurgeons may remove it through surgery. After surgery, radiotherapy may be given to the area where the tumor was removed.
Overall, there are different treatment options available depending on the specific situation, and your doctor will discuss the best approach for you.
What is proton therapy?
Proton therapy is a special kind of radiation treatment that was first developed for children with brain tumors. It helps reduce long-term side effects in kids.
In regular radiation therapy, healthy tissues absorb some radiation after it reaches the tumor. This is called the exit dose. But with proton therapy, the protons stop inside the tumor, so there is no exit dose and less harm to healthy tissues. Proton therapy is important for children, but there is no evidence that it’s better than other types of radiation therapy for adults. Before considering proton therapy, talk to your doctor and discuss your treatment options and location.
How do I prepare for radiation?
Before starting treatment, you’ll go through a simulation procedure to prepare for radiation. You’ll lie down on a table, and therapists will create a mesh mask or chin strap to help you stay in the right position. Images of your head will be taken to plan the angles and shapes of the radiation beams. You might also get small tattoos or markings on your skin as guides for the therapists.
Your doctor will give you instructions on how to prepare for the treatment day. During brain radiation, you’ll be placed in the same position as during the simulation, and the therapists will leave the room. They will be able to see and hear you throughout the procedure. You can breathe normally but try to stay still. If you’re worried, talk to your doctor about ways to stay calm.
Is brain radiation safe? What are the side effects?
Brain radiation is generally safe, and your body doesn’t become radioactive after treatment, so it’s fine to be around people.
Focused radiation mostly targets tumor cells and has minimal side effects on normal cells. However, there is a possibility of swelling called radiation necrosis when the radiated normal cells surrounding the tumor die off. Swelling can be managed with steroids and a drug called bevacizumab. In some cases, surgical removal may be needed.
Immunotherapy and certain targeted drugs can increase the risk of radiation necrosis. Symptoms of necrosis depend on the location in the brain and may include confusion, loss of movement, and speech difficulties. Radiation necrosis can occur months or even years after treatment. Whole brain radiation therapy (WBRT) can cause short-term fatigue and long-term aging of the brain, including radiation dementia. Medications like memantine and methylphenidate (Ritalin) can help reduce these risks and manage symptoms of slowed thinking.
It is possible to live well after brain radiation. Keep your brain active with activities like reading, puzzles, and conversations. Stay in close contact with your doctor and let them know about any side effects you experience. Pseudo-progression is when a lesion outside the brain appears to get bigger before getting smaller during immunotherapy.
However, when it comes to brain metastases, radiation necrosis can look like disease progression due to inflammation. It’s more important to find a care team that works together rather than seeking a specialist who only focuses on the specific part of the body where cancer has spread. Look for a team where the medical oncologist treating your lung cancer collaborates with radiation oncologists or neurological oncologists. Communication among team members about patient goals, expectations, and side effect management is crucial.
At the 2023 American Society of Clinical Oncology Annual Meeting, researchers shared a study on using a radionics approach to predict brain metastases (BM) in patients with non-small cell lung cancer (NSCLC).
An Approach for Predicting Brain Metastases in Lung Cancer Patients
Brain metastases are common in NSCLC, with around 40% of patients developing brain tumors. However, there are currently no reliable ways to predict the risk of brain metastases, especially in the early stages when an MRI is not performed.
To address this, lead investigator Xincheng Wu and colleagues studied 162 lung adenocarcinoma (LUAD) patients, out of which 66 had brain metastases and 96 did not. They used a method called Least Absolute Shrinkage and Selection Operator (LASSO) logistic regression to select the most important features for analysis. They created models using a machine learning method called XG Boost classifier. They used training and testing sets for cross-validation and reported the accuracy, sensitivity, specificity, and area under the curve (AUC) for each model.
The results showed that the XGBoost model accurately predicted brain metastases with 79% accuracy, 83% sensitivity, 72% specificity, and 79% AUC (p=0.01) in the overall population. The model also distinguished between patients with metachronous (occurring at different times) and synchronous (occurring at the same time) brain metastases with 84% accuracy, 83% sensitivity, 86% specificity, and 83% AUC (p=0.04). Importantly, the model was effective in predicting brain metastases in early-stage patients with 92% accuracy, 96% sensitivity, 83% specificity, and 95% AUC (p=0.0005). The researchers noted that the model specifically predicted survival outcomes related to brain metastases and not other sites of metastasis.
The researchers concluded that their radiomics approach successfully predicted brain metastases using lung CT features, including in stage I and II disease. The model also distinguished between different molecular subtypes of LUAD. They mentioned that they are currently validating their prediction model in a large independent group of patients and developing models to identify LUAD patients with targetable molecular alterations using brain MRI scans. These studies will help identify patients who require MRI surveillance in the early stages and more intensive surveillance in the later stages for brain metastases.
