When lung cancer spreads out of the lung — called metastatic lung cancer — it often metastasizes (spreads) to the bone. Lung cancer tumors formed in the bone are called bone metastases. This metastasis can cause symptoms like pain, fractures, constipation, and confusion. If you develop bone metastasis, your doctor may make changes to your cancer treatment regimen.

Read on to find out more about metastasis to the bones and what it might mean for your lung cancer journey.

What Is Bone Metastasis?

When lung cancer first forms, tumor cells grow in the location where they started and remain attached together. However, in advanced stages of lung cancer, cancer cells begin to separate from one another. When this happens, they can enter the bloodstream and travel to other parts of the body to form new tumors. At this point, it’s considered stage 4 lung cancer (sometimes written with Roman numerals as “stage IV lung cancer”). When lung cancer cells spread to the bone, they can influence bone cells to help build tumors.

Lung cancer can affect two types of bone cells: osteoblasts, which help to create new bone tissue, and osteoclasts, which break down existing bone tissue.

The way metastatic bone disease behaves depends on which type of bone cell is influenced by cancer cells. In most people with lung cancer that spreads to their bones, their osteoclasts become cancerous. This leads to bone damage called osteolytic lesions. This type of bone metastasis is referred to as osteolytic metastasis.

Osteoblasts may interact with the lung cancer cells, but osteoblastic metastasis is so rare that research hasn’t yet confirmed that it happens.

Prevalence of Lung Cancer With Bone Metastasis

When lung cancer metastasizes, the bones are one of the most common sites it spreads to. More than 30 percent of people with advanced lung cancer have bone metastases. Many of these cases are people with non-small cell lung cancer (NSCLC), the most common type of lung cancer. Bone metastases are present at the time of diagnosis in about 20 percent to 30 percent of people with NSCLC. Among those who don’t have bone metastases at diagnosis, 35 percent to 60 percent will develop them later.

People with small cell lung cancer (SCLC), the other main type of lung cancer, are also commonly affected by bone metastasis. Approximately two-thirds of people with SCLC already have bone metastases at the time they’re diagnosed with cancer.

Symptoms of Lung Cancer With Bone Metastasis

Although some people don’t have any symptoms, bone metastases usually cause a number of problems in the body. Most notably, you might experience pain in your bones. The pain might be worse at certain times of the day or when you move.

Additionally, your bones may become very weak and break easily, even with only minor activities. Broken bones can cause a sharp, sudden pain and most commonly occur in the limbs or the back.

Bone metastasis can also lead to hypercalcemia, which is high levels of calcium in the blood. If you have high blood calcium, you may need to urinate frequently or have problems passing a bowel movement due to constipation.

Hypercalcemia can also cause:

• Weak or achy muscles and joints
• Feelings of confusion
• Feelings of slowness and sleepiness
• Intense thirst
• Coma

Hypercalcemia may also lead to kidney failure. You may need urgent treatment to avoid damage to your kidneys.

Some people with bone metastases may experience more severe pain in the neck or back. This pain is often caused by spinal cord compression, which occurs when tumors form in the spine and press on the nerves.

Spinal cord compression may cause other symptoms, such as:

• Numbness or weakness in the legs
• Difficulty moving your legs properly
• Inability to control urination or bowel movements

Spinal cord compression is an emergency situation that can cause paralysis if it’s not treated quickly enough. If you notice severe pain or any other symptoms of spinal cord compression, seek medical attention right away.

Diagnosis of Bone Metastasis

Doctors check for bone metastasis using an imaging test that helps them see cancer cells in your bones or bone marrow. Positron emission tomography (PET) scans are often used to help look for bone metastases. For a more sensitive test to find cancer cells, a PET scan may be performed together with a computed tomography (CT) scan.

Doctors may use other imaging tests such as:

• X-ray
• Bone scan
• Magnetic resonance imaging (MRI)

If imaging isn’t enough to confirm whether you have bone metastases, a biopsy may be recommended to help with diagnosis. To perform a biopsy, your doctor will collect a sample of cells from your bone. They can then look at the sample more closely using laboratory tests to see if there are cancer cells in the bone.

Treatments for Bone Metastasis

Bone metastasis occurs in advanced-stage lung cancer, which generally cannot be cured. However, there are many treatments that can help manage symptoms and slow the growth of cancer. This type of treatment is known as palliative care.

Managing Bone Pain

Because bone pain is one of the most common symptoms of bone metastasis, many people will take medication to help decrease their pain. Different treatments that may be used for pain control include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Acetaminophen (Tylenol)
• Opioids
• Steroid drugs
• Anti-seizure medication

Slowing Growth or Shrinking Bone Metastasis

Doctors may also treat bone metastases from lung cancer with drugs known as bisphosphonates. These drugs help stop osteoclasts from dividing. Zoledronic acid (Reclast) is one example of a bisphosphonate prescribed to treat bone metastasis.

Radiation therapy is also commonly used to treat people with bone metastases. Also called radiotherapy, it uses high-powered X-rays to destroy cancer cells in specific parts of the body. People often have less bone pain following radiation. Chemotherapy drugs — which specifically kill quickly dividing cells — are also widely used.

Immunotherapy drugs — drugs that target cells of the immune system — may also be used to treat lung cancer with bone metastasis. This class of drugs includes monoclonal antibodies, which can recognize certain proteins on the surface of certain cells. Denosumab (Xgeva) is a monoclonal antibody that can slow the growth and division of osteoclasts.

Targeted therapies are drugs that only target one type of protein. This class includes drugs like receptor tyrosine kinase inhibitors, which may be used to treat people who have specific mutations (changes) in their tumor DNA.

Surgery may be recommended in some cases of metastatic lung cancer, though it’s generally not the first choice of treatment. Doctors may choose surgery to remove bone tumors causing spinal cord compression. Surgery comes with significant risks, so it’s generally performed only when absolutely necessary.

Prognosis of Lung Cancer With Bone Metastasis

Metastatic lung cancer is difficult to treat, so it has an overall poor prognosis (outlook). One study found that the survival rate for people with lung cancer and bone metastasis was 11.3 percent at two years after diagnosis. This means that after two years, 11.3 percent of people remained alive. Although overall survival was low, the study found that people with only one bone tumor were more likely to live longer. People treated with chemotherapy or targeted therapy also had a better prognosis.

More research is needed to find better treatments for metastatic lung cancer and improve the prognosis of people with bone metastases. Talk to your doctor about your treatment options, which may include clinical trials. Some clinical trials test promising new therapies to see if they’re more effective against metastatic lung cancer than existing treatment options. Participating in a clinical trial may give you an opportunity to try out a new therapy that could improve your quality of life.

Talk With Others Who Understand

On MyLungCancerTeam, the social support network for people with lung cancer and their loved ones, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand.

Are you living with lung cancer and bone metastasis? What symptoms have you experienced, and what’s worked to manage them? Share your insights in the comments below, or start a conversation by posting on your Activities page.