What Is Metastatic Lung Cancer?

Metastatic lung cancer is cancer that starts in the lungs and spreads (metastasizes) to other parts of the body, such as the liver, brain, or bones. It is the most advanced lung cancer stage and is sometimes referred to as a stage 4 cancer.

Although metastatic lung cancer is challenging to treat, newer drugs are increasing survival times and quality of life for people who are diagnosed with this advanced disease.

Types of Metastatic Lung Cancer

There are numerous types of lung cancer. While they can all metastasize if not treated, some are more likely to do so than others.

• Non-small cell lung carcinoma (NSCLC): This most common type of lung cancer includes the subtypes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. They generally grow and spread more slowly than small cell lung cancer. According to the American Cancer Society, 80% to 85% of lung cancers are NSCLC.
• Small cell lung carcinoma (SCLC): Also known as oat cell cancer, this fast-growing, highly aggressive type of cancer accounts for 10% to 15% of lung cancers.
• Carcinoid tumors: These are very slow-growing neuroendocrine tumors that affect hormone-producing cells in the lungs. Those classified as typical carcinoids rarely grow beyond the lungs. Atypical carcinoid tumors tend to grow a bit faster and are more likely to spread to other organs.
• Pleural mesothelioma: This rare and locally aggressive type of lung cancer is most often caused by exposure to asbestos.

Metastatic Lung Cancer Symptoms

Even after lung cancer reaches an advanced stage, the most common symptoms can be relatively subtle or easily mistaken for less serious medical issues. This is so much so that 57% of lung cancers have already metastasized by the time they're diagnosed.

The most common lung cancer symptoms include:

• Persistent cough
• Shortness of breath on exertion
• Multiple chest infections, such as bronchitis or pneumonia
• Hemoptysis (coughing up blood)
• Unexplained weight loss
• Pain in the chest, back, arm, or shoulder area

As lung cancer metastasizes, other symptoms can develop:

• Brain metastases: Dizziness, visual changes, balance problems, headaches, seizures 
• Bone metastases: Pain, fractures, spinal cord compression
• Liver metastases: Jaundice (yellowing of the skin), abdominal swelling 
• Adrenal gland metastases: Weight loss, abdominal pain, nausea, vomiting, back pain, weakness, fatigue, fever, confusion 

Cause and Sites of Spread

Distant lung cancer metastasis occurs when tumor cells break away from where they originally developed and travel to other parts of the body.

The most common sites of lung cancer metastasis are:

• Other lung
• Brain
• Bones
• Liver
• Adrenal glands

The process usually begins with local metastasis: when the cancer cells invade tissues close to the primary site. From there they can enter nearby lymph nodes and blood vessels and travel beyond the affected lung via the lymphatic system or bloodstream.

Along the way, the cancer cells might leave the lymphatic vessels or blood vessels and settle into tissues where they continue to grow.

Diagnosis

Metastatic lung cancer may be detected due to monitoring being done because of a localized lung cancer diagnosis or because symptoms of spread prompted someone to seek an evaluation. Less often, it may be caught during screening.

Lung cancer is diagnosed using a variety of methods. Once a diagnosis is confirmed, it is further defined by stage—a classification that describes how advanced it is and that helps direct treatment.

Exam and Testing

The following may be done to detect and stage lung cancer:

• Physical examination: A healthcare provider will take a complete medical history and symptom profile, do a full physical examination, listen to your lungs, examine your fingernails, and feel your lymph nodes.
• Imaging: Various imaging studies used to help visualize a tumor in the lungs can include chest X-ray, computerized tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET).
• Lung biopsy: A biopsy involves removing a sample of tissue so that it can be examined under a microscope. This is done to determine the type of lung cancer. There are several methods for doing this: bronchoscopy, endobronchial ultrasound (performed during a bronchoscopy), fine needle biopsy, thoracentesis, and mediastinoscopy.
• Pulmonary function tests (PFTs): These evaluate lung capacity and can help determine the degree to which a tumor is interfering with breathing. PFTs include spirometry, a diffusion test, and lung plethysmography.
• Other laboratory tests: Other tests that may be used in the process of lung cancer diagnosis include blood tests, sputum cytology, gene testing, PD-L1 testing, and liquid biopsy.

Screening

Regardless of whether or not someone is experiencing symptoms, the U.S. Preventive Services Task Force recommends that certain people be screened for lung cancer using CT once a year.

You fall into this group if you:

• Are 50 to 80 years old
• Have a 20 pack-year or more history of smoking
• Currently smoke or have quit within the past 15 years
• Are generally well enough to undergo treatment if lung cancer is diagnosed

Staging

Cancer is staged to describe the extent to which it has spread and, therefore, the severity of disease. The two most common lung cancers are staged using different systems.

Non-small cell lung cancer has four main stages: 0 to 4.

NSCLC is regarded as stage 4 when it has spread to the second lung, the fluid around the lung or heart, or other distant body areas. 

There are two degrees of stage 4 metastatic NSCLC: stages 4a and 4b.

SCLC is more commonly classified according to two stages:

• Limited-stage SCLC: Cancer is present on only one side of the chest. Treatment can be with a single radiation field. In most circumstances, the cancer is only in one lung, but it might have reached the lymph nodes on the same side as that lung.
• Extensive-stage SCLC (metastatic lung cancer): Cancer has spread widely throughout a single lung or it may have spread to the second lung, lymph nodes far from the tumor, or other parts of the body (including the fluid around the lung).

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Treatment

Unfortunately, metastatic lung cancer is not easily treated. At stage 4, the tumor is no longer confined to a separate discreet area and it may be affecting organs and systems in the body other than the lungs.

For these reasons, treatment often is focused on palliative care—relieving symptoms, improving quality of life, and extending life—rather than attempting to cure cancer.

Palliative care takes into account not only someone's physical needs, but their psychological, spiritual, and social needs as well.

Options for NSCLC

The approach to treating stage 4 NSCLC may differ somewhat from that for stage 4 SCLC.

• Gene mutation testing will often be performed before treatment. If specific gene mutations are identified, then targeted drug therapy will often be the first treatment line.
• Also, tumor cells may be tested for the PD-L1 protein. If higher levels of this protein are found, then the cancer is more likely to respond to specific immunotherapy drugs.

Additional treatment options may include surgery, chemotherapy, radiation, or a combination of all three. Treatment will be further refined based on specific locations of metastases and effects of the tumor.

For example, if there is fluid in the tissues that line the heart or lungs (pericardial or plerual effusion), it may need to be removed. If there is a single brain metastasis, it might be treated with surgery and radiation.

In May 2020, the Food and Drug Administration approved Tabrecta (capmatinib) for adults diagnosed with aggressive stage 4 NSCLC that has spread to other parts of the body and whose gene testing shows MET Exon 14 skipping mutations. It can be prescribed as a first-line treatment for them as well as previously-treated patients.

Options for SCLC

SCLC has spread too far for surgery or radiation therapy to be successful as an initial treatment.

As such, chemotherapy and immunotherapy are used in the first-line treatment of extensive-stage SCLC. The combination of these two treatments is designed to shrink cancer, alleviate symptoms, and help you live longer.

If cancer responds to this, then radiation therapy might also be introduced. The goal of radiation is to help prolong life; radiation might also be considered to prevent cancer progression in the brain.

Immunotherapy, when combined with an anti-angiogenic agent, chemotherapy, or radiation, is thought to be the most promising SCLC treatment that has emerged in recent years.

Prognosis

The prognosis for metastatic lung cancer typically is measured in terms of survival rates. The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute collects and publishes detailed information about cancer incidence and survival in the United States.

The SEER database tracks five-year relative survival rates for NSCLC and SCLC. The five-year survival rate is the percentage of people who are expected to be alive five years after diagnosis. 

The SEER program categorizes data and survival estimates into three stages of lung and bronchus cancer:

• Localized: Confined to the primary site
• Regional: Spread to regional lymph nodes
• Distant: Spread to other parts of the body

Please note that these are broad estimates and may not apply to your particular situation.

^{United States data; unstaged cases not included}

Survival estimates have limitations, though. They reflect the entire population of people with lung cancer, regardless of age, health, cancer grade, or cancer type.

Cancer survival estimates can give a general idea about the survival rate of most people in your situation. However, they can't tell you your chances of curing your cancer or achieving remission as an individual.

Coping

During treatment, your healthcare provider, medical team, family, and friends can help you cope with metastatic lung cancer lifestyle changes, symptoms, and treatment side effects.

Reach out to them for help and emotional support and also consider these measures:

• Learn: Get information about the disease, metastasis, staging, and treatments. Some people find that increasing their knowledge in these areas helps them face what's ahead. Ask your medical team as many questions as you need to.
• Talk: Get a referral to a healthcare professional who you can talk to about your worries, emotions, and situation. They will be able to help you with coping strategies, psychological support, and lifestyle changes.
• Take time out: Living with and managing cancer can be overwhelming and stressful. For your physical and mental health, be sure to schedule some downtime to do something that helps you relax.
• Find a support network: Sometimes it helps to speak to other people who have been through or are in the same cancer stage as you. Ask your healthcare provider about local support groups that you could attend, or seek out online support or social media groups.
• Focus on things you enjoy: Give yourself time to do something that makes you happy. Plan your activities for times of the day where you have the most energy and not much else to do.

If you are worried about how your family is coping with your diagnosis, encourage them to seek help too. There are in-person and online support groups for family members and caregivers just like there are for patients.

A Word From Verywell

The reality of metastatic lung cancer is a lot to process. But remember that advances in treatment have increased life expectancy. Survival rates are improving year by year, and death rates from lung and bronchus cancers have been improving 3.6% on average each year since 2009.

There are also many ongoing clinical trials. These studies give participants a chance to try the newest treatments. If you have been diagnosed with metastatic lung cancer and want to know how to be considered for a clinical trial, speak with your medical team about your options.