Bone Metastasis

Bone metastasis occurs when cancer cells from a primary tumor, such as breast or lung cancer, spread to the bones. This is a secondary cancer, meaning it did not start in the bone itself. It can cause pain, weaken bones, and lead to complications like fractures or nerve problems, but treatments are available to manage symptoms and improve quality of life.

What is Bone Metastasis?

Bone metastasis is a condition where cancer cells from a tumor elsewhere in the body travel and grow in the bones. This means the cancer in the bone is not a primary bone cancer, but rather a secondary cancer that has spread, or metastasized, from its original location. It is a serious complication of many advanced cancers.

When cancer cells break away from their original tumor, they can travel through the bloodstream or lymphatic system to other parts of the body. If these cells settle and grow in the bones, it is called bone metastasis. Bone metastases can affect any bone, but they are most commonly found in the spine, pelvis, ribs, skull, and the long bones of the arms and legs. These new tumors can weaken the bone, leading to pain and other problems. It is important to understand that bone metastasis is named after the original cancer. For example, if breast cancer spreads to the bone, it is still called metastatic breast cancer, not bone cancer. This distinction helps guide treatment decisions.

Symptoms

The most common symptom of bone metastasis is pain in the affected bone, which can be constant and worsen over time or at night. Other symptoms include weakened bones that break easily, nerve problems from spinal cord pressure, and high calcium levels in the blood, which can cause fatigue and confusion.

Bone pain is often the first and most noticeable symptom. This pain can be a deep ache, constant, and may feel worse during activity or at night. The pain usually occurs in the area where the cancer has spread, such as the back, hips, or ribs. Bone metastases can weaken bones, making them more fragile. This can lead to what are called pathologic fractures, which are breaks that occur from minor injury or even everyday activities that would not normally cause a fracture. For example, a simple fall might cause a bone to break. If cancer spreads to the spine, it can press on the spinal cord, a condition called spinal cord compression. This can cause symptoms like back pain, numbness or weakness in the arms or legs, and problems with bladder or bowel control. High levels of calcium in the blood (hypercalcemia) can also occur when bones break down too quickly. Symptoms of hypercalcemia include nausea, vomiting, constipation, extreme thirst, frequent urination, fatigue, and confusion.

Causes & risk factors

Bone metastasis is caused by cancer cells from a primary tumor breaking away and traveling to the bones. While any cancer can potentially spread to bone, certain types are more likely to do so, including cancers of the breast, prostate, lung, kidney, and thyroid, as well as multiple myeloma.

The process begins when cancer cells detach from the original tumor. These cells then enter the bloodstream or lymphatic system, which are the body's transportation networks. Once in these systems, they can travel throughout the body. If these circulating cancer cells find their way to the bone marrow, they can settle there and begin to grow, forming new tumors. The exact reasons why some cancers spread to bone more often than others are still being studied, but it involves complex interactions between the cancer cells and the bone environment. While the risk of bone metastasis increases with advanced stages of these primary cancers, it's important to note that not everyone with these cancers will develop bone metastases. The likelihood depends on many factors, including the specific type and aggressiveness of the primary cancer.

How it's diagnosed

Diagnosing bone metastasis typically involves a combination of imaging tests and sometimes a biopsy. Doctors use scans like X-rays, CT, MRI, PET, and bone scans to look for changes in the bones. A biopsy, where a small tissue sample is taken, can confirm the presence of cancer cells.

When bone metastasis is suspected, your doctor will likely order several tests. Imaging tests are crucial for seeing the bones and identifying any areas where cancer might have spread. These include X-rays, which can show bone damage; computed tomography (CT) scans, which provide detailed cross-sectional images; and magnetic resonance imaging (MRI), which is very good at showing soft tissues and bone marrow. A bone scan is another common test. For this, a small amount of radioactive material is injected into your bloodstream. This material collects in areas of increased bone activity, which can indicate cancer. Positron emission tomography (PET) scans can also detect cancer cells throughout the body. In some cases, a biopsy may be needed to confirm the diagnosis. During a biopsy, a small sample of bone tissue is removed from the suspicious area, usually with a needle. A pathologist then examines this tissue under a microscope to confirm if cancer cells are present and to identify their origin.

Treatment options

Treatment for bone metastasis focuses on managing pain, preventing complications like fractures, and improving quality of life. Options include medications to strengthen bones and relieve pain, radiation therapy, chemotherapy, hormone therapy, targeted therapy, immunotherapy, and sometimes surgery. Your care team will tailor a plan to your specific needs.

Pain management is a key part of treatment and may involve over-the-counter pain relievers, prescription pain medications, or nerve blocks. Medications called bisphosphonates (like zoledronic acid) and denosumab are often used to strengthen bones, reduce pain, and help prevent fractures and other bone-related complications. These drugs work by slowing down bone breakdown. Radiation therapy uses high-energy rays to shrink tumors and relieve pain in specific areas of the bone. It is often very effective for localized pain. Systemic treatments, which affect the whole body, include chemotherapy, hormone therapy, targeted therapy (drugs that attack specific vulnerabilities in cancer cells), and immunotherapy (which helps your immune system fight cancer). Surgery may be an option to stabilize a weakened bone, repair a fracture, or remove a tumor that is pressing on the spinal cord. Other procedures, such as ablation (using heat or cold to destroy tumor cells), might also be considered. The choice of treatment depends on the type of primary cancer, the extent of the spread, your overall health, and your symptoms.

Recovery & outlook

The outlook for bone metastasis varies greatly depending on the original cancer and how widely it has spread. While bone metastasis is generally not curable, treatments can effectively manage symptoms, slow cancer growth, and significantly improve a person's quality of life. Recovery focuses on symptom control and maintaining function.

Living with bone metastasis often involves ongoing management rather than a cure. The goal of treatment is to control the cancer's spread, reduce pain, prevent further bone damage, and maintain your ability to perform daily activities. Many people can live for months or years with bone metastasis, with good symptom control. Your recovery journey will likely involve regular follow-up appointments to monitor the cancer and adjust treatments as needed. This may include continued medication, physical therapy to help maintain strength and mobility, and supportive care to address any side effects of treatment or emotional challenges. Palliative care is an important part of managing bone metastasis. This type of care focuses on providing relief from the symptoms and stress of a serious illness, aiming to improve quality of life for both the patient and their family. It can be provided alongside curative treatments from the time of diagnosis.

When to see a doctor

You should see a doctor if you experience new or worsening bone pain, especially if it's severe or constant. Seek immediate medical attention if you notice new weakness or numbness in your arms or legs, difficulty walking, or changes in your bowel or bladder control, as these could signal a serious complication like spinal cord compression.

It's important to report any new or changing symptoms to your healthcare team promptly. Even if you are already being treated for cancer, new pain or changes in existing pain should be evaluated. This includes pain that doesn't go away, gets worse at night, or is not relieved by your usual pain medication. If you experience sudden, severe pain in a bone, or if you suspect a bone fracture, you should contact your doctor right away. This could indicate a pathologic fracture that needs immediate attention. Emergency signs that require immediate medical care include any new or worsening weakness, tingling, or numbness in your limbs, difficulty moving your arms or legs, or any new problems with controlling your bladder or bowels. These symptoms could mean the cancer is pressing on your spinal cord, which needs urgent treatment to prevent permanent damage.

Frequently asked questions

Can bone metastasis be cured?

Bone metastasis is generally not curable, meaning the cancer cannot be completely eliminated from the body. However, treatments are highly effective at controlling the cancer's growth, managing symptoms like pain, and preventing complications. The goal is to improve your quality of life and extend life as much as possible.

Is bone metastasis always painful?

Bone metastasis often causes pain, which is its most common symptom. However, some people may not experience pain, especially in the early stages. The pain can vary from a mild ache to severe, constant discomfort. It's important to report any new or changing pain to your doctor.

What is the difference between bone cancer and bone metastasis?

Bone cancer starts in the bone cells themselves. Bone metastasis, on the other hand, is cancer that started in another part of the body (like the breast or lung) and then spread to the bone. The treatment and outlook for these two conditions are often very different.

How quickly does bone metastasis spread?

The rate at which bone metastasis spreads varies greatly depending on the type of primary cancer and individual factors. Some cancers may spread slowly, while others can progress more rapidly. Regular monitoring with your healthcare team helps track its progression and adjust treatment as needed.

Can diet or lifestyle changes help with bone metastasis?

While diet and lifestyle changes cannot cure bone metastasis, maintaining a healthy diet, staying active (as advised by your doctor), and avoiding smoking can support your overall health and well-being during treatment. These choices may help manage symptoms and improve your quality of life.

What are bone-strengthening medications for bone metastasis?

Bone-strengthening medications, such as bisphosphonates (e.g., zoledronic acid) and denosumab, are commonly used for bone metastasis. These drugs work by slowing down the breakdown of bone, which helps to reduce pain, prevent fractures, and lower the risk of other bone-related complications. They are given as infusions or injections.

Sources

• MedlinePlus — Bone Metastasis
• Mayo Clinic — Bone Metastasis
• Cochrane Library — Bone Metastasis