What Happens When Lung Cancer Spreads To Bone

Lung cancer with bone metastases refers to the spread of cancer from the primary (original) tumor to the bone. The spread of cancer cells occurs either through the bloodstream or lymphatic system (a system of fluids, vessels, and organs that protect the body against foreign invaders).

Bone metastases from lung cancer affect between 30% and 40% of people with advanced lung cancer. The bones are the third most common site for metastases, after the liver and adrenal glands, among people with lung cancer.

Although lung cancer that has spread to bone is not curable, there are treatments that can lengthen survival times and improve quality of life. Moreover, it’s important to note that bone metastases are not all the same. Some have more favorable outcomes than others.

This article points out which bones lung cancer are likely to affect and which symptoms and complications are likely to appear. It also explains how the condition is diagnosed and treated.

Affected Bones

According to a review in Therapeutic Advances in Medical Oncology, the most common bones to which lung cancer spreads include (in order of frequency) the:

Clear Any Confusion

Lung cancer with bone metastases is not the same thing as bone cancer, in which cancer originates in the bones.

• Spine
• Ribs
• llium (the widest part of the the pelvic bones)
• Sacrum (the triangular bone at the base of the spine)
• Femur (thigh bone)
• Humerus (upper arm bone)
• Scapula (shoulder blade)
• Sternum (breastbone)

Lung cancer can also spread to bones in the hands and feet.

Symptoms of Bone Metastases From Lung Cancer

Pain is typically the first symptom of bone metastases. At least, it is in about 80% of cases. The pain may initially feel like a dull muscle strain but gradually intensifies and becomes severe. The pain is often worse at night or with movement.

If bone metastases involve the spine, compression of the spinal cord by the tumor may initially present with back pain as well as limb weakness. Numbness and paresthesia (a burning, prickly sensation) may also occur in areas below the site of the spinal compression.

The compression of nerves in the lumbar spine, referred to a nerve root compression, can cause radicular pain. The condition, also known as referred pain, is characterized by shooting pain in other distant parts of the body due to the pressure placed on nerves in the lower spine.

Complications

Bone metastases from lung cancer can cause severe complications as the malignancy progresses. These complications undermine the spine and the integrity of the bones and cause metabolic changes that can compromise a person’s ability to function.

Cauda Equina Syndrome

Metastatic spinal cord compression (MSCC) can often present as a medical emergency. There may initially be localized edema (swelling around the site of the compression) and venous congestion (the disruption of normal blood flow). If treated early, these conditions can be reversed.

However, prolonged venous congestion due to MSCC can lead to severe vascular injury, spinal cord necrosis (tissue death), and permanent spinal cord damage.

In rare cases, metastatic spinal cord compression can lead to cauda equina syndrome, resulting in limb weakness, sciatica (radiating pain in the lower back and legs), the loss of reflexes in lower extremities, and the loss of bowel and/or bladder function.

Pathological Fractures

Sometimes, the first sign of lung cancer metastasis to the bone is a fracture. This is referred to as a pathological fracture. The integrity of the bone is compromised as normal bone tissues are supplanted by cancer cells. These fractures can occur without any significant trauma, often spontaneously while performing everyday tasks or even rolling over in bed.

Prompt Reaction Matters

Cauda equine syndrome is considered a medical emergency. If not treated promptly (typically with surgery), the symptoms can become permanent.

Pathological fractures are generally preceded or accompanied by constant pain. Pain from fractures in the spine or ribs will generally worsen while sitting or standing. Sciatica, deformity, and immobility are common outcomes of a pathological fracture due to bone metastases.

Hypercalcemia and Anemia

The breakdown of bone and the release of calcium into the bloodstream can cause a condition known as hypercalcemia (abnormally high blood calcium). Symptoms include extreme thirst, weakness, nausea or vomiting, decreased urination, and muscle and joint aches.

In people with bone metastases, hypercalcemia is considered a medical emergency and can lead to cardiac arrhythmia (abnormal heart rhythm), disorientation, and even death if not appropriately treated.

Bone metastases may also cause myelophthisic anemia, a severe type of anemia caused by the displacement of bone marrow with cancer cells. It typically occurs as the malignancy progresses, causing fatigue, weakness, shortness of breath, and low tolerance to exercise and physical activity.

Diagnosis

Bone metastases from lung cancer are diagnosed with imaging studies. In addition to confirming that cancer has spread to the bones, imaging studies can help identify the type of bone metastases involved. Imaging tests used for the diagnosis of bone metastases include:

• X-rays can sometimes spot lesions caused by the loss of bone mineral, but only when the lesions are large.
• Computed tomography (CT) scans employ multiple X-ray images to create three-dimensional “slices” of internal organs and structures. They are more sensitive than X-rays and better able to differentiate between types of bone lesions.
• Magnetic resonance imaging (MRI) scans use powerful magnetic and radio waves to create highly detailed images. MRIs are more sensitive and specific than X-rays and CT scans in diagnosing bone metastases. They can be used safely in pregnant women due to the lack of ionizing radiation.
• Positron emission tomography (PET) scans are extremely sensitive in diagnosing bone metastases as they are able to detect abnormally active cell growth characteristic of cancer.
• Bone scans are used less commonly today as they often cannot distinguish cancer from other bone conditions.

These imaging tests would be supported by blood tests, including a complete blood count (CBC), to check for anemia and other blood cell abnormalities, and a comprehensive metabolic panel (CMP) to help identify hypercalcemia before it becomes serious.

Classification

The classification of bone metastases can help doctors predict the likely course and outcome of the disease. Unlike lung cancer staging, the classification of bone metastases does not direct how the disease is treated. Rather, it gives the doctor an idea of how the metastases will progress.

Primary Tumor Holds the Key

Tissue biopsy and histology (the microscopic examination of tissues and cells) are not typically used in cases of bone metastasis unless the site of the primary tumor is unknown.

Bone metastases are typically classified based on imaging studies as follows:

• Osteolytic: Characterized by the loss of bone mineral, it leads to softened areas of bone (osteolytic lesions).Sclerotic: As an abnormal increase in the thickness and density of tissues, it leads to the formation of thick spots (sclerotic lesions) on the bone.Mixed: Some people with bone metastases have both osteolytic and sclerotic lesions.

Of the three, sclerotic metastases (also referred to as osteoblastic metastases) tend to progress more slowly than osteolytic metastases. Moreover, sclerotic metastases are less commonly associated with hypercalcemia than osteolytic metastases, which can actively leach calcium into the bloodstream.

Treatment

The treatment for lung cancer with bone metastases is primarily palliative—that is, it’s meant to relieve symptoms rather than cure cancer. The primary goal of treatment is to reduce pain and either prevent or treat fractures and other serious complications.

With this said, for people with only a few metastases (referred to as oligometastatic disease), oncologists may consider treating the metastases aggressively with the hope of long-term survival.

Treatment options for bone metastases can be broadly classified as being either systemic (involving the whole body) or local (involving bone or bone-related symptoms).

Systemic Treatments

For most people with bone metastases, the treatment of the primary tumor may not only help control the spread of the disease but also provide pain relief. Common options include:

• Chemotherapy is typically used as the main treatment for metastatic cancer. It can help shrink tumors, slow the progression of the disease, and alleviate pressure on nerve roots and within bones that causes pain.
• Targeted therapies are a newer form of treatment that target and kill cancer cells with specific genetic mutations. Genetic profiling is conducted to see if someone is a good candidate for treatment. Therapy options include drugs such as Tarceva (erlotinib), Tagrisso (osimertinib), and Xalkori (crizotinib).
• Immunotherapy drugs work by harnessing your immune system to directly fight cancer. Opdivo (nivolumab) and Keytruda (pembrolizumab) are two drugs approved for such use.

Local Treatments

The local treatment of bone metastases is mainly directed at providing pain relief and preventing fractures and spinal compression. Options include:

Consider a Clinical Trial

Clinical trials might be worth considering if you have advanced lung cancer with metastases, particularly if your current therapies aren’t providing adequate control of the disease.

• Analgesics: These pain killers are typically prescribed in a specific order based on their strength and side effects. Stronger nonsteroidal anti-inflammatory drugs (NSAIDs) like Celebrex (celecoxib) may be used first, followed by opioids like hydrocodone, fentanyl, and morphine if pain control cannot be achieved.
• Corticosteroids: Known simply as steroids, corticosteroids provide pain relief by tempering the immune response and reducing inflammation. They can support other pain treatments but are used cautiously due to the risk of side effects. Dexamethasone is a commonly prescribed oral steroid for people with cancer pain.
• Radiation therapy: Radiation is commonly used to reduce pain, prevent fractures, and relieve spinal cord compression from bone metastases. Most people get substantial pain relief from radiation therapy, and some are able to achieve sustained relief with just one session.
• Stereotactic body radiotherapy (SBRT): This form of radiation therapy delivers extremely precise, intense doses to cancer cells while minimizing damage to healthy cells. SBRT appears to provide better pain control with a single dose compared to multiple doses of standard external beam radiation. It can also be used to remove metastases in people with one or a few metastatic tumors in the hope of achieving disease remission.
• Osteoclast inhibitors: Osteoclasts are cells in bones that break down bone tissues. Osteoclasts inhibitors, including bisphosphonates and denosumab, are drugs that inhibit destruction of the bone. They are prescribed to prevent the deterioration of bone in people with bone metastases. Options for people with lung cancer include the drug zoledronic acid (a bisphosphonate) and denosumab, which are delivered every few weeks by injection or intravenous infusion.
• Surgery: Surgery is used primarily to stabilize bones if they fracture or to prevent a fracture in a bone that is weakened by cancer. Some of the options include orthopedic fixation (using metal screw and plates to stabilize or repair bone) and vertebroplasty (the injection of bone cement into spinal bones to prevent or relieve spinal compression).

Prognosis

The median survival time for people with bone metastases from lung cancer—that is, the amount of time after which 50% of people are alive and 50% have died—has increased in recent years. The increase is due to the ever-growing range of cancer treatment options. However, it still hovers at about 10 months.

It’s important to remember that some people have survived and lived a good life for many years beyond this prognosis. Your general health at the time of the diagnosis and during treatment can play a large part in determining how long you can live successfully with the disease.

Summary

Lung cancer with bone metastases refers to the spread of cancer from the primary (original) tumor to the bone. The most common bones to which lung cancer spreads include the spine, ribs, ilium, sacrum, femur, humerus, scapula, and sternum. The spread of cancer cells occurs either through the bloodstream or lymphatic system. Pain is typically the first symptom of bone metastases. At least it is in about 80% of cases. The pain may initially feel like a dull muscle strain but gradually intensifies and becomes severe. The pain is often worse at night or with movement.

Survival Times Vary

Survival times are somewhat longer for women and people under 60 as well as those with lung adenocarcinoma, a single metastasis, or no history of fractures. People with sclerotic bone lesions also tend to survive longer than those with osteolytic or mixed bone metastases.

Bone metastases from lung cancer can cause severe complications as the malignancy progresses. These complications undermine the spine and the integrity of the bones and cause metabolic changes that can compromise a person’s ability to function. Bone metastases from lung cancer are diagnosed with imaging studies, after which treatment is primarily designed to relieve the symptoms rather than cure the cancer. The options can be broadly classified as being either systemic (involving the whole body) or local (involving bone or bone-related symptoms).

A Word From Verywell

Having bone metastases from lung cancer means that your cancer is stage 4 and no longer curable. As difficult as it is to hear this news, don’t give up hope. With properly staged palliative care, you can maintain a good quality of life with the support of your family and friends.

To help you through the rough times, join a support group of others who understand what you’re going through. Seek counseling from a psychologist or psychiatrist if you’re depressed, anxious, or unable to cope. Try not to focus on survival times. Instead, make every effort to care for yourself emotionally and physically so that you can continue to live the best life you can—probably like you have up to this point.