What Happens When Lung Cancer Spreads to the Brain?
Lung cancer is the most common type of cancer to spread to the brain, with at least 40 percent of people with lung cancer developing brain metastases at some point during their disease. What are the symptoms, what is the treatment, and what is the prognosis for lung cancer that has spread to the brain?
Definition of Lung Cancer Spread to the Brain
First of all, it is important to define lung cancer that has spread to the brain.
When lung cancer spreads to the brain it is termed "lung cancer metastatic to the brain." The term "brain cancer" in contrast, refers to cancer that begins in the tissues of the brain. Most cancers found in the brain are not brain cancers per se –- that is, they don’t start in the brain itself. Lung cancer spreads to the brain when cancer cells break off from the tumor in the lung, and spread through the bloodstream or lymphatic system to the brain and begin to grow.
What Type of Lung Cancers Spread to the Brain?
Both small cell lung cancer and non-small cell lung cancer commonly spread (metastasize) to the brain. Small cell lung cancer can spread to the brain rapidly, often before the diagnosis of lung cancer is made. When small cell lung cancer has spread to the brain it is classified as extensive stage small cell lung cancer.
Non-small cell lung cancer can spread to the brain as well, though often later in the disease.
When non-small cell lung cancer has spread to the brain it is classified as stage 4 (metastatic) non-small cell lung cancer.
Symptoms of Lung Cancer That Has Spread to the Brain
Lung cancer that has spread to the brain can cause symptoms both by destroying brain tissue and by creating inflammation and swelling that place pressure on structures in the brain.
The symptoms of lung cancer spread to the brain can vary, depending upon the part of the brain that is affected, how many tumors are present in the brain, and general health status. About a third of people have no symptoms when they have brain metastases. Some of the symptoms that suggest lung cancer may have spread to the brain include:
- Loss of balance
- Nausea and vomiting
- Difficulty walking
- Loss of coordination
- Speech problems
- Vision changes, such as loss of vision or double vision
- Weakness on one side of the body
- Memory loss
- Personality changes
Diagnosis of Lung Cancer Spread to the Brain
If your doctor suspects that your lung cancer has spread to your brain, she may order a CT scan or an MRI of your head. In many cases, an MRI is more accurate in looking for brain metastases, but may not be possible if devices (such as pacemakers) are present in your body that could interfere with the magnetic field.
PET scans, a type of radiological study that looks for actively growing cancer cells, may be done to decide if a suspicious area in the brain is due to cancer or scar tissue. Sometimes a biopsy is done to look at the cells present in the brain, especially if it is uncertain where the cancer began.
Treatment of Lung Cancer That Has Spread to the Brain
The treatment of lung cancer that has spread to the brain depends upon how extensive the spread is (for example, how many spots of cancer are present in the brain), your overall health, and the progression of your cancer. Since the goal of treatment is not to cure the cancer, therapy should be chosen with consideration of quality of life in mind foremost.
The risks and benefits of the different treatment options should be discussed carefully with your oncologist, taking into account your individual situation and preferences.
The first goal of treatment is to control any complications of brain metastases. Steroids, such as decadron, may be used to control swelling in the brain. If seizures are present, anti-seizure medications may be used. Pain medications may be used to control headaches. Choices for specific treatment may then include:
- Whole-Brain Radiotherapy: This is usually the treatment of choice if there are tumors that can’t be seen or if more than three tumors are present. Whole-brain radiotherapy may also be used to lower the risk of brain metastases after other treatments, such as surgery. While not meant to cure cancer, at least 50% of people notice some improvement in their symptoms with whole-brain radiotherapy. Common side effects can include memory loss (especially verbal memory), skin rash, and fatigue.
- Stereotactic Radiotherapy (Stereotactic Radiosurgery): This is not actually surgery, but rather a form of radiation in which a higher dose of radiation
is given to a specific area of the brain. Since the radiation is delivered to only a specific region, side effects may be less severe than with whole-brain radiotherapy. Names that you may be familiar with for stereotactic radiotherapy includeGamma knifeorCyberknife . Stereotactic radiotherapy is usually reserved for people who have three or fewer tumors present in their brain, and in this setting, may improve survival more than whole-brain radiation alone.
- Surgery: Surgery is occasionally performed to remove lung cancer that has spread to the brain if only a single tumor (or possibly more) is present, the tumor can be easily reached, and if there are no signs of cancer spread in other parts of the body. In this setting, surgery may be done to remove the tumor, or to reduce the size (debulk) the tumor to relieve symptoms. When surgery is performed, it is usually followed up with whole-brain radiation to improve the outcome. Surgery is done more often for non-small cell lung cancers since small cell lung cancers are usually more sensitive to radiation.
- Chemotherapy: Due to the "blood-brain barrier," a tight layer of cells that keeps poisons from entering the brain, chemotherapy has not been found to be very effective for brain metastases from lung cancer. That said, several medications, including radiosensitizers (medications that can make cancer cells more susceptible to radiation treatments), are currently being evaluated in clinical trials to assess their effect on brain metastases.
- Comfort Care: Even when specific therapy is not felt to be helpful, there are still many things that can be done to ease the symptoms of lung cancer that has spread to the brain. Pain medications may help with headaches. Physical and/or occupational therapy may be used to maximize functioning and independence. In addition, many cancer centers are now incorporating complementary treatments, such as massage and acupuncture, to help people cope with the anxiety and other symptoms related to brain metastases.
Prognosis of Lung Cancer that Has Spread to the Brain
Sadly, those who have been diagnosed with lung cancer metastatic to the brain have a median survival of only 4 months. This is the time after which 50 percent of people remain alive and 50 percent have died from their disease. That said, among people who have treatment for oligometastses (only a few metastases) to the brain, outcomes are highly variable, and long-term survivors do exist.
Bottom Line on Brain Metastases From Lung Cancer
Brain metastases due to lung cancer may be terrifying. You may have already experienced symptoms, or worry that you will experience symptoms which affect who you are as a person.
At the same time that the symptoms of brain metastases are frightening and can be debilitating, many medical treatments (such as chemotherapy and targeted therapies) are unable to cross the blood-brain barrier to address these metastases.
Yet, there are positives now with brain metastases. SBRT can sometimes resolve these metastases (if there are only one or a few) and some people have had long term control of their disease even with breast metastases.
In addition to radiation and surgery to treat metastases, research is in progress today evaluating treatments, such as targeted therapies, which appear to have a unique ability to address brain metastases.
Ashworth, A. et al. Is there an oligometastatic state in non-small cell lung cancer? A systematic review of the literature.Lung Cancer . 2013. 82(2):197-203.
Gaspar, L. et al. The role of whole brain radiation therapy in the management of newly diagnosed brain metastases: a systematic review and evidence based clinical practice guideline.Journal of Neuro-oncology . 2010. 96(1):17-32.
Kalkanis, S. et al. The role of surgical resection in the management of newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline.Journal of Neuro-oncology . 2010. 96(1):33-43.
Linskey, M. et al. The role of stereotactic radiosurgery in the management of patients with newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline.Jounral of Neuro-oncology . 2010. 96(1):45-68.
Mehta, M. et al. The role of chemotherapy in the management of newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline.Journal of Neuro-oncology . 2010. 96(1):71-83.
Ricciardi, S. and F. de Marinis. Multimodality management of non-small cell lung cancer patients with brain metastases.Current Opinion in Oncology . 2010. 22(2):86-93.
Walbert, T. and M. Gilbert. The role of chemotherapy in the treatment of patients with brain metastases from solid tumors.International Journal of Clinical Oncology . 2009. 14(4):299-306.
Yamanaka, R. Medical management of brain metastases from lung cancer (Review).Oncology Reports . 2009. 22(6):1169-76.
Villarreal-Garza, C. et al. Agressive treatment of primary tumor in patients with non-small-cell lung cancer and exclusively brain metastases.Clinical Lung Cancer . 2013. 14(1):6-13.