What is Metastatic Lung Cancer?

Cancer happens when abnormal cells grow, multiply and form tumours. In such instances, cancerous cells can invade and kill healthy tissue. However, sometimes they can spread to other body parts.

Unfortunately, cancers like lung cancer are challenging doctors to discover in their early stages.

There are two key forms of lung cancer: non-small-cell lung cancer and small-cell lung cancer.

And even when patients exhibit symptoms, like a cough or tiredness, they might not feel ill enough to see a doctor. As a result, most people tend to get diagnosed after cancer becomes advanced and spreads.

What is metastasis?

Fundamentally, the spread of cancer is scientifically called metastasis. Any cancer that has spread is referred to as metastatic. This means that metastatic lung cancer is one that begins in the lungs and starts to spread to other body areas.

Essentially, this means that cancer cells start to separate themselves from a tumour and travel via the blood or lymph system to other body parts and tissues. Lung cancer may have already metastasised before the patient goes in for a diagnosis or the metastasis could happen during the course of the treatment.

Generally, as cancerous cells accumulate in the lungs, they can also slowly invade healthy surrounding tissues. Though in most instances, they initially spread to other parts of the lung (local metastasis).

Unfortunately, once the cancerous cells invade the lymph nodes, they can quickly travel through the lymphatic system to other body parts, and form secondary tumours in other organs (distant metastasis).

At times, a person may even have undergone effective treatment for one type of cancer, then developed second cancer elsewhere in the body. But this isn’t metastatic cancer.

Metastatic lung cancer stages

Metastatic cancer is sometimes referred to as advanced, extensive-stage cancer or Stage IV.

Metastasis is usually a gradual process that causes few if any, side effects until the tumour becomes large enough to affect the neighbouring organs.

Overall, metastatic lung cancers are typically Stage 4, depending on how wide the tumour has grown and spread.

Unfortunately, most people with lung cancer do not even notice symptoms until cancer has extensively spread. Furthermore, in most cases, visible symptoms come from metastasis instead of the original site of the tumour.

For the most part, metastatic lung cancer cells tend to have the same features as the original lung cancer cells, when examined by a pathologist under a microscope.

Which is the most common site for metastasis in lung cancer?

If lung cancer spreads, it usually invades areas like the:

Opposite lung
Lymph nodes
Liver
Bones
Brain
Adrenal glands

What causes metastatic lung cancer?

Most body cells have a limited life cycle. And as they die, new ones form. Lung cancer basically develops when abnormal cells in the lungs continue multiplying, without dying.

Consequently, the excess cells form a tumour. And as it grows, it requires more space and starts spreading to other areas. This is the point cancer becomes metastatic.

In principle, cancerous lung cells affect the body in five main ways:

By entering and invading into the neighbouring tissues and forming a progression of the tumour
By breaking away from the tumour then traveling through the bloodstream or lymphatic system to other body parts
By growing through the walls of nearby blood vessels
Invading into blood vessels forming blood clots
Increasing the growth of blood vessels, which supply additional blood and oxygen to the tumour

What are the symptoms of metastatic lung cancer?

When lung cancer spreads or 'metastasizes', it can trigger various symptoms. However, at the start, the symptoms tend to be concentrated in the upper part of the chest, such as:

Chronic cough
Shortness of breath
Chest pain

However, if cancer continues spreading to other parts of the body, the symptoms can become more sophisticated and wide-ranging. In these scenarios, symptoms vary based on where cancer has spread.

Furthermore, the speed at which lung cancer spreads also varies from patient to patient.

Lung cancer that spreads to bones

Bones are a common destination for lung cancer metastases, most especially the upper arm bones, the pelvic bone, and the spine.

Generally, bone metastases cause chronic pain in the affected bone, while also making it more prone to fracturing. For spinal metastases, the tumour can even compress one of the neighbouring nerves or nerve roots, leading to neurological symptoms like pain that radiates down an arm or leg.

Lung cancer that spreads to the brain

The brain is one of the most common places for lung cancer to spread. Brain metastases tend to create pressure inside the skull, potentially leading to seizures, headaches, blurred vision, and problems with balance and memory.

Lung cancer that spreads to the liver

Lung cancer can also spread to the liver, where it can interfere with proper liver function. Symptoms range from jaundice, swelling in the abdomen to a sensation of constant fullness.

How is metastatic lung cancer diagnosed?

Sometimes, doctors do not diagnose cancer before it spreads. However, the first diagnostic tests for metastases involve checking the areas where lung cancer typically spreads via blood tests, ultrasound scans, bone scans, X-rays, CT scans, and MRI scans.

Computed tomography (CT) Scan: Similar to MRI scans, CT scans provide detailed images to help find out whether lung cancer has spread to the lymph nodes, liver, adrenal glands, brain, or other organs.
Magnetic resonance imaging (MRI): MRI is reserved to evaluate central neurological evaluation, for example, nerve root compression or brain metastases (occult). This diagnostic test creates detailed images of inside the body to ascertain whether lung cancer has spread either to the spinal cord or brain.
Positron emission tomography (PET): PET scan is mainly used for detailed staging in preparation for surgical resection. PET scans help show exactly where cancer cells are located in the body. Typically, before a PET scan, the patient receives an injection of a substance (radioactive sugar) meant to travel throughout the body. The substance typically settles in any area(s) with cancer cells, therefore indicating the presence and location of cancer.
Bone scans: These scans focus on detecting whether lung cancer has reached the bones. Similar to PET scans, bone scans also require an injection of a radioactive substance that tends to become concentrated in bones that contain cancerous cells.

What are the treatment options for metastatic lung cancer?

Unfortunately, most times, when lung cancer is metastatic, it is in a late stage and can be quite challenging to treat. However, the treatments and outcomes vary from person to person.

Fundamentally, there are several variables that can possibly influence treatment, such as the patient's age, overall health, or the body part cancer has travelled to.

Overall, most treatment plans focus on slowing or stopping the spread of cancerous cells and alleviating the patient's symptoms to improve their quality of life. These treatment plans are subjected to the type of lung cancer. For example:

Chemotherapy - to help slow the systemic growth of cancer cells (small cell lung cancer and non-small cell lung cancer)
Immunotherapies - to exploit the body's ability to fight disease non-small cell lung cancer)
Targeted drug therapy - to help attack cancer cells with specific gene mutations (non-small cell lung cancer)

What is the life expectancy for metastatic lung cancer?

Researchers typically base cancer survival rates on the exact type of cancer, its subtype, and the stage at diagnosis. According to the American Lung Association data, lung cancer accounts for 25% of all cancer fatalities. Hence making it the leading cause of death among people with cancer, with an overall 5-year survival rate of about 18.6%.

Though still relatively low compared to other cancers, this rate represents an improvement. In 2013, for example, researchers estimated that the survivability rate was about 16%, so this is a little over a 2% improvement.

Generally speaking, lung cancer tends to become more serious and difficult to treat as it progresses. Metastatic lung cancers also generally have very low survival rates. For context:

Patients with metastatic non-small cell lung cancer that has spread to distant organs typically have a five-year relative survival rate of 7%, according to ACS. However, if cancer only spreads to a neighbouring tissue, the survival rate improves to 35%. Though patients with localised lung cancer, which hasn't spread at all, have a 63% survival rate.

For metastatic small cell lung cancer patients that’s widespread in the body, the five-year relative survival rate is 3%

Preventing and controlling metastasis

All things considered, some specialised cancer treatments may help slow or stop metastasis by making conditions less suitable for the growth of cancerous cells.

For example, anti-angiogenic drugs can stop tumours from growing their own blood vessels as cutting off the blood supply to the tumour can dramatically slow or prevent its growth.

Furthermore, tyrosine kinase inhibitors (TKIs) can prevent or reduce tumour growth by blocking growth signals within, or between cancer cells.

Though scientists are continuously investigating other ways to prevent cancer from spreading, it’s not always possible to prevent lung cancer or to fully keep it from spreading.

However, one can take steps like avoiding things that significantly increase the risk of developing lung cancer—for example, smoking. Additionally, remember that treatment is more likely to be effective in the early stages of metastatic cancer, so receiving a diagnosis and treatment early may help prevent cancer from widely spreading.

Book an appointment at Pantai Hospitals

A cancer diagnosis can be overwhelming and deciding on cancer treatments can be a challenge. A dedicated and expert team of oncologists at Pantai Hospitals is available for consultation to provide the best care and assistance to patients through cancer screening, diagnosis, and treatment.

Get in touch with us to book an appointment today if you have any concerns or questions about cancer treatment options.

Pantai Hospitals have been accredited by the Malaysian Society for Quality in Health (MSQH) for its commitment to patient safety and service quality.

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