When Lung Cancer Spreads to the Brain

Symptoms, Diagnosis, and Treatments for Brain Metastases

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Lung cancer is known to spread to the brain in about 40 percent of people in which a metastasis has occurred. Metastasis is the medical term used to describe a cancer which has spread beyond the initial tumor to a different, distant organ system. With lung cancer, this is considered stage 4 of the disease.

In the past, brain metastases with lung cancer heralded a poor prognosis, with life expectancy usually being under a year. Traditional treatments for brain metastases, such as chemotherapy, are most often ineffective since they do not cross the blood brain barrier. In recent years, there has been more hope for at least some people.

Some drugs in the newer treatment categories classified as targeted therapies or immunotherapy are able to cross this barrier, and when a single or only a few brain metastases are present, local treatment (such as SBRT) of these metastases can, in some cases, lead to long-term control of the disease.

Here's what you need to know about identifying symptoms and obtaining diagnosis, treatment, and more.

symptoms of lung cancer with brain metastases
Illustration by Brianna Gilmartin, Verywell

Overview

When metastases happen in people with lung cancer, the secondary malignancy is not considered a "brain cancer" but rather "lung cancer metastatic to the brain" or "lung cancer with brain metastases." In contrast, the term brain cancer is used for those tumors which originate in the brain as the primary, rather than secondary, malignancy. In other words, if you were to take a sample of the cancer cells in the brain they would be cancerous lung cells, not cancerous brain cells.

Sadly, lung cancers with metastases to the brain have a relatively poor prognosis, but this is changing for some people. Unlike many chemotherapy drugs, some of the newer targeted therapies for lung cancer are able to penetrate the blood-brain barrier and can help fight lung tumors which have spread to the brain. There are also new options available for those who have only a few metastases to the brain (sometimes defined as oligometastases).

The average survival time with brain metastases is usually less than a year, but when only isolated metastases (oligometastases) are found and can be treated, over 60 percent of people may survive for two years or longer. In addition, people who can be treated with some targeted therapies may survive much longer.

If you have lung cancer with brain metastases, your treatment and prognosis may be different than for someone with the same condition just a year or two ago. It's important to learn all you can and be your own advocate.

As an example, a 2018 study found that people who are treated with appropriate therapy for ALK positive lung cancer, the median survival rate for those with stage 4 lung cancer, even with brain metastases, was 6.8 years. Unfortunately, not everyone diagnosed with stage 4 non-small cell lung cancer is tested or offered treatment.

Symptoms

Brain metastases can occur with either small cell lung cancer or non-small cell lung cancer. Small cell lung cancer is often difficult to diagnose in the early stages and, as a result, may spread to the brain before a diagnosis is even made. Non-small cell cancers can also spread to the brain but tend to do so later in the course of the disease after the primary tumor has been discovered.

Symptoms can vary based on the type of lung cancer and where in the brain the metastases occur. As many as a third of all people with secondary brain cancer will have no symptoms whatsoever, and the spread is found on imaging tests (such as a brain MRI). If they do occur, they typically include:

  • Headaches
  • Fatigue
  • Loss of balance
  • Nausea and vomiting
  • Difficulty walking
  • Loss of coordination
  • Speech problems
  • Vision changes, including loss of vision or double vision
  • Peripheral weakness (occurring on one side of the body)
  • Memory loss
  • Personality changes
  • Seizures

Diagnosis

If your doctor suspects that your lung cancer has spread to your brain, he or she will order imaging tests such as computed tomography (CT scan) which use X-rays to create diagnostic images or a magnetic resonance imaging (MRI) which does the same with magnetic waves. While an MRI is considered more accurate, it may not be used in persons with certain metal implants (including non-safe pacemakers).

Another type of imaging tool is positron emission tomography (PET scan) which is able to differentiate between normal cell metabolism and those which appear hyperactive (such as cancer cells). If a suspicious lesion is found but the diagnosis is uncertain, a biopsy may be performed to obtain a tissue sample for evaluation.

Brain Metastases vs. Leptomeningeal Metastases

Leptomeningeal metastases (leptomeningeal carcinomatosis) tend to be a late complication of advanced lung cancer, and are being seen more commonly as survival rates improve. Unlike brain metastases, leptomeningeal metastases occur when lung cancer cells seed the leptomeninges, the innermost layers of the membranes that surround the brain. Since they float freely within the cerebrospinal fluid that bathes the brain and spinal cord, they don't need to form large tumors to ensure a supply of nutrients.

Symptoms of leptomeningeal metastases often include multiple neurological symptoms. Treatment may include intrathecal chemotherapy (injecting chemotherapy drugs directly into the cerebrospinal fluid) though some targeted drugs, such as some used to treat EGFR mutations, BRAF mutations, and ALK rearrangements, may enter the spinal fluid and be effective.

Treatment

The treatment of brain metastases depends on a number of factors including how much of the brain is involved and your overall health. If brain metastases are widespread, treatment is focused on controlling the symptoms and complications in order to optimize quality of life. If there are only a few metastases, local treatment to eliminate the metastases entirely is often pursued.

Steroids such as Decadron (dexamethasone) may be used to control any swelling of the brain, while anticonvulsive medications (seizure drugs) can reduce the incidence and severity of seizures. Other treatments can be broken down into general treatments for stage 4 lung cancer, treatments for widespread brain metastases, and localized treatments for oligometastases.

General Treatments

General treatments for cancer wherever it is present may include:

Chemotherapy

Many chemotherapy drugs are ineffective in treating brain metastases due to the presence of the blood-brain barrier, a tight network of capillaries which serves to keep toxins (including chemotherapy drugs) out of the brain. Chemotherapy may, however, reduce the size of tumors in the lungs and therefore limit their ability to spread to the brain.

Targeted Therapy

Targeted drugs for EGFR mutations, ALK rearrangements, ROS rearrangements, and others are sometimes able to penetrate the blood-brain barrier. Some of the newer drugs for EGFR mutations as well as therapies for ALK rearrangements appear to be very effective at treating brain metastases. Like chemotherapy, these drugs also control the primary tumor and thus limit its ability to spread to the brain.

Immunotherapy

It's still too soon to know much (the first immunotherapy drug for lung cancer was approved in 2015) but the four immunotherapy medications (checkpoint inhibitors) approved for lung cancer show promise in their ability to reduce brain metastases. For some people, these drugs have led to both control of metastases and a "durable response" to the cancer as a whole. According to a 2018 study published in the Journal of Clinical Oncology, checkpoint inhibitors do appear to be effective in treating brain metastases.

This is further supported by a 2019 study published in the Journal of Thoracic Oncology that found that people with non-small cell lung cancer who were treated with immunotherapy drugs did not (as would have been expected) have a poorer survival rate if they had brain metastases.

Whole Brain Radiotherapy

If there are several brain metastases present (cancer centers vary in defining this and the number may be greater than three to greater than 20), whole-brain radiotherapy has traditionally been recommended. Whole-brain radiation may be a good choice for those who have symptoms related to their brain metastases or who are at risk for complications (such as a stroke). It can also be used after surgery to reduce further spread of the cancer. While not designed to cure cancer, at least 50 percent of people undergoing whole-brain radiotherapy will notice some improvement in symptoms. Common side effects can include memory loss (especially verbal memory), skin rash, and fatigue. Radiation oncologists often recommend a medication which appears to reduce cognitive dysfunction related to this treatment.

If whole brain radiotherapy has been recommended for your brain metastases, talk with your doctor about the advantages and disadvantages of this treatment, alternatives available, and medications that may reduce the side effects. This is currently an area of controversy in the management of lung cancer, and a second opinion may be warranted before beginning treatment.

Brain-Metastasis Specific Treatments

Treatments which specifically address brain metastases but designed to treat widespread metastases:

Stereotactic Radiotherapy

Also known as stereotactic radiosurgery or SBRT, this is a type of high-dose radiation given to a specific area of the brain. Since the radiation is targeted, side effects are typically less severe and offer better survival rates than whole-brain therapy. This form of radiotherapy is usually reserved for people with three or fewer tumors, although some people have had this treatment for up to 20 tumors.

Proton Therapy

Proton therapy is used in a way similar to SBRT, and is done in an attempt to eradicate the metastases which are present.

Surgery

Surgery is used less commonly but may be an option if there are one or a couple of tumors that are easily accessed, and there are no signs of cancer elsewhere. Surgery may involve the complete removal of a tumor or the partial removal to alleviate symptoms. Whole-brain radiation typically follows. Since small-cell tumors are more responsive to radiotherapy alone, surgery is more often used to remove non-small cell cancers.

Palliative Care

If the various treatment options prove ineffective, palliative care may be used to offer relief and reduce stress associated with a terminal diagnosis. This may include the use of pain medications, physical and occupational therapy, or complementary treatments to enhance comfort and improve the quality of life.

A Word From Verywell

Brain metastases due to lung cancer can be terrifying. But, as scary as it may be, it's important to remember that there is no set course when it comes to cancer. It can vary from person to person, and the "median" or "average" life expectancies you'll read about don't necessarily apply to you as an individual.

If faced with brain metastases from lung cancer, work with your doctors and loved ones to make the most informed choice based a full and honest disclosure of information. It is often helpful to get a second opinion at one of the larger National Cancer Institute-designated cancer centers which specialize in lung cancer. Even if the treatment is the same, you and your family may feel more confident that you're on the right course.

It's important to allow yourself to feel what you feel and to seek support to help navigate this journey. Reach out to your family and friends. There is a very active lung cancer community online, and becoming active in these groups can not only bring support from people who are living a similar journey and "get it," but are also an excellent resource through which to ask questions and learn about the latest advances in lung cancer treatment; including those related to the treatment of brain metastases.

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Article Sources

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