Bone Metastases

What bone metastases are

Cancer cells can break away from a primary tumor, travel in the blood, and settle in the bone marrow, especially in bones with rich blood supply such as the spine, pelvis, ribs, skull and the upper ends of the femur and humerus. Once there, they disrupt the normal balance of bone being broken down and rebuilt.

• Osteolytic (destructive) metastases eat away bone, weakening it. Typical of breast, lung, kidney and thyroid cancer and myeloma.
• Osteoblastic (bone-forming) metastases create abnormal, dense but brittle bone. Typical of prostate cancer.
• Mixed lesions have both.

A cancer that has spread to bone is still named after its origin. Breast cancer in the bone is "metastatic breast cancer", not bone cancer. Primary bone cancers such as osteosarcoma are different and much rarer.

Symptoms

• Bone pain: the most common symptom. It is often dull and constant at first, worsening over weeks, and typically worse at night and with weight-bearing.
• Fractures with little or no trauma (pathological fractures), especially of the ribs, spine, hip and upper arm.
• Back pain with leg weakness, numbness or bladder changes, a sign of spinal cord compression.
• High calcium (hypercalcemia): thirst, passing a lot of urine, constipation, nausea, tiredness and confusion.
• Anemia and infections when the bone marrow is heavily involved.

Some bone metastases cause no symptoms and are found on scans done to stage the cancer.

Complications

Spinal cord compression

A tumor in a vertebra can collapse it or grow into the spinal canal, pressing on the spinal cord. It needs emergency treatment, usually high-dose steroids and urgent radiation or surgery, because once paralysis develops it is often permanent. See spinal cord compression.

Fractures

Weakened bones break easily. A hip or thigh bone at high risk of breaking may be stabilized with a metal rod before it fractures. See pathological fractures.

High calcium

Bone breakdown releases calcium into the blood. Hypercalcemia is treated with IV fluids and bone-strengthening drugs.

Diagnosis

• X-rays of painful areas, although lesions show only after significant bone loss.
• Bone scan: detects areas of increased bone activity throughout the skeleton.
• CT and MRI: MRI of the whole spine is the test of choice for suspected spinal cord compression.
• PET-CT: including PSMA-PET for prostate cancer, shows active cancer throughout the body.
• Blood tests: calcium, alkaline phosphatase, kidney function, and tumor markers such as PSA.
• Biopsy when the original cancer is unknown or to check how the cancer has changed.

Treatment

Treatment is tailored to the original cancer, the number and location of metastases, symptoms and overall health. It is usually planned by a multidisciplinary team.

Treating the cancer

• Hormone therapy for hormone-sensitive breast and prostate cancers
• Chemotherapy, targeted therapy and immunotherapy
• Radiopharmaceuticals: radium-223 for prostate cancer that has spread mainly to bones, and lutetium-177 PSMA therapy for some advanced prostate cancers

Bone-modifying drugs

• Bisphosphonates (such as zoledronic acid) and denosumab slow bone destruction and reduce fractures, spinal cord compression and the need for radiation.
• A rare side effect is osteonecrosis of the jaw, so a dental check before starting and good oral hygiene are important. Calcium and vitamin D are often prescribed with them.

Radiation therapy

External beam radiation relieves pain in most people, often with a single treatment. Stereotactic body radiotherapy delivers high doses precisely to limited metastases.

Surgery and procedures

• inserting rods, plates or joint replacements to fix or prevent fractures
• spinal surgery to relieve compression and stabilize the spine
• vertebroplasty or kyphoplasty, injecting bone cement into collapsed vertebrae for pain
• radiofrequency or cryoablation of painful lesions

Pain and supportive care

Pain is managed with a step-up approach: acetaminophen (paracetamol), anti-inflammatories, and opioids when needed, plus nerve pain medicines. Physical therapy, mobility aids and palliative care teams improve comfort and independence at every stage.

Outlook

Bone metastases mean the cancer is advanced and usually cannot be cured, but they are often very treatable. Survival varies widely by cancer type. Many people with breast or prostate cancer that has spread only to bone live for several years with good quality of life on modern treatments, whereas lung cancer metastases often carry a shorter outlook. Your oncology team can give a personal estimate.

Frequently asked questions

What are the first signs of bone metastases?

The most common first sign is new bone pain that persists and gradually worsens, often at night or with weight-bearing. Other signs include a fracture after minor trauma, back pain with leg weakness or numbness, or symptoms of high calcium such as thirst, constipation and confusion.

Which cancers spread to bone most often?

Breast, prostate, lung, kidney and thyroid cancers are the solid tumors that most often spread to bone. Multiple myeloma, a blood cancer, also commonly affects the bones. Breast and prostate cancer account for the majority of bone metastases.

Can bone metastases be cured?

They are rarely curable, but they can often be controlled for long periods. Treatment aims to slow the cancer, relieve pain, prevent fractures and spinal cord compression, and maintain quality of life. Some people with a few metastases may receive treatment aimed at long-term control.

How long can you live with bone metastases?

It depends on the type of cancer, how much it has spread and how it responds to treatment. People with breast or prostate cancer limited to bone often live several years. Lung cancer with bone spread generally has a shorter outlook. Your oncologist can discuss your situation.

How is pain from bone metastases treated?

Radiation therapy relieves pain in most people, often after one session. Pain medicines, bone-strengthening drugs, cancer treatment, and procedures such as bone cement injections or surgical stabilization also help. Palliative care specialists can tailor pain control.