Bone Metastasis

Bone is one of the most frequent sites of metastasis, which can be caused by nearly all cancer types. However, some types of cancer have a higher risk of spreading to the bones, such as breast cancer, prostate cancer, thyroid cancer, lung cancer, bladder cancer, kidney cancer and melanoma. Bone metastasis can occur in any bone, but more commonly in the spine, pelvis and thigh. It can cause pain or even fracture of the long bones or collapse of the spine.

• Pain
  • Pain is often the earliest, and the most common symptom detected.
  • Patients may experience localised pain, which is pain at a particular site.
  • The pain is often described as persistent and gradually increasing.
  • If the cancer spreads to the spine, patients may experience worse pain at night or in a lying posture.
  • If the long bones are involved, e.g. arms or legs, the pain may be worsened during movement.
• Bone fracture
  • A fracture is a medical term to describe a broken or cracked bone.
  • Impending fracture implies that the bone is about to break.
  • X-ray or CT scan can be used in case of suspicion.
• Spinal cord compression
  • If the cancer spreads to the spine and extends posteriorly to the spinal cord, it can result in spinal cord compression. This can cause numbness and weakness of the limbs, urinary or bowel problems, and paralysis.
• Other symptoms
  • Anaemia, symptoms of hypercalcemia, loss of appetite, nausea, fatigue

Your doctor may order these tests:

• X-ray
  • To check for lytic or sclerotic lesions in the bones.
  • To check for fractures in the long bones or collapse in the spine.
• CT scan
  • CT scans are generally more sensitive than X-rays. Shapes of tumours and soft tissue extensions in the body can be clearly observed.
• Magnetic Resonance Imaging (MRI)
  • MRI is especially useful for detecting bone metastasis in the spine.
  • It is used to assess if the spinal cord or nerves are involved by bone metastasis.
• Bone scan or PET-CT
  • Bone scan and PET-CT are nuclear medicine scans that can assess any spread of cancer within all bones of the body.
  • They are more sensitive and more specific than X-rays and CT scans.

• Osteolytic (bone destruction)
  • When the cancer cells affect the bones, it will cause holes or lytic lesions to appear, which can be shown on X-rays.
  • Typically arises from cancers in the kidney, thyroid, uterus or intestines.
• Osteoblastic (abnormal bone formation)
  • Characterised by deposition of new bones.
  • Commonly present in prostate cancer, carcinoid and small cell lung cancer.
• Mixed
  • Mixture of both osteolytic and osteoblastic lesions.
  • Generally occurs in carcinomas of the lung, breast, cervix, ovaries and testicles.

Pain Relief

• Painkillers or analgesics are often needed for patients with bone metastasis. The pain medications include opioids and non-opioids. More information about the types of pain medications can be found in the Pain section.

Radiotherapy

• Radiotherapy often provides excellent palliation for localised metastatic bone pain. Over 50% of patients had pain relief 1-2 weeks after completion of radiotherapy. 
• Indication of radiotherapy for bone metastasis include pain, risk of pathologic fracture and spinal cord compression.

Surgical Therapy

• Often indicated in patients with
  • Spinal instability evidenced by pathological fracture, progressive deformity, and/or neurological deficit.
  • Fractures or impending fractures in the long bones.
  • Tumours that are insensitive to radiotherapy, chemotherapy or hormonal therapy.

Bone-modifying agents

1. Bisphosphonate is a class of medications shown to be effective in treating bone metastasis.

• Example: zoledronic acid, pamidronate, ibandronate
• Administration: usually given through IV line (intravenously)
• Can reduce risk of skeletal related events, such as pain, fractures and collapse of the spine
• Its dosage may need to be adjusted or reduced in patients with renal impairment.

2. Denosumab

• Denosumab is a human monoclonal antibody that inhibits the RANKL, preventing the development of osteoclasts.
• It is suitable for patients with impaired renal function.
• Administration: subcutaneous injection

Side effects of bisphosphates and denosumab include:

• Nausea
• Diarrhoea
• Sustaining bone pain over a few days after injection
• Osteonecrosis of the jaw
  • An uncommon side effect of bisphosphates and denosumab
  • Found in 0.6-1% of patients
  • To prevent, it is recommended to have dental procedures before initiation of the drug and avoid dental procedures while using it. Moreover, a 2-3 week-gap between initiation and dental procedure is recommended.

Radiopharmaceutical Therapy

• This is a systemic use of radioisotopes for bone metastasis. It involves the injection of radioactive isotopes that releases radiation particles in the patient. The radiation omits cancer cells in bones and is absorbed.
• Example: radium-223
• Radium-223 is used for castration-resistant prostate cancer patients with bone metastases. It can improve the overall survival and relieve bone pain.
• Side effects: 
  • Decrease in white cell and platelet count, anaemia, as well as pain flares
  • Side effects often subside soon after completion of treatment.

▶️ Take a closer look: Know more about Bone Metastasis 

American Society of Clinical Oncology (ASCO): Bone metastasis

Canadian Cancer Society: Bone metastasis

Special thanks to Mr. Joshua Tang, Ms. Candice Leung, and Dr. Wendy Wing-Lok Chan, Department of Clinical Oncology, the University of Hong Kong for authoring and editing this article.

Last updated on 1 Nov 2021.