What we need to know about metastatic bone disease

Metastatic bone disease (MBD) occurs when cancer from another part of the body spreads to the bones. It is a common complication of advanced cancers, particularly those originating in the breast, prostate, lung, thyroid, and kidneys. The bones most frequently affected include the spine, pelvis, ribs, and long bones of the arms and legs. MBD can significantly impact a patient's quality of life, leading to pain, fractures, and mobility issues.

Causes and pathophysiology

Cancer cells spread to the bones through the bloodstream or lymphatic system. Once in the bone, these cells disrupt the normal balance of bone formation and resorption, often leading to areas of weakened bone (osteolytic lesions) or excessive bone formation (osteoblastic lesions). This imbalance results in pain, fractures, and other complications, depending on the extent and location of the metastases.

Symptoms

Patients with MBD commonly experience bone pain that worsens over time and may become severe, particularly at night or with activity. Other symptoms include swelling, limited mobility, and a heightened risk of fractures, even with minimal trauma.

In some cases, spinal metastases can compress the spinal cord, causing neurological symptoms such as weakness, numbness, or loss of bladder and bowel control, which requires urgent medical attention.

Diagnosis

Diagnosis of metastatic bone disease involves imaging studies, such as X-rays, CT scans, MRIs, and bone scans, to identify the extent and location of bone involvement. Blood tests may reveal elevated calcium levels or markers of bone turnover. A biopsy of the bone may be performed to confirm the diagnosis and identify the primary cancer if it is unknown.

Treatment options

The primary goals of MBD treatment are to manage pain, maintain mobility, and prevent fractures. Treatments include medications like bisphosphonates or denosumab to strengthen bones and reduce bone resorption. Radiation therapy can target specific bone lesions to relieve pain and prevent complications.

In some cases, surgical intervention is needed to stabilize fractures or decompress the spinal cord. Systemic cancer treatments, such as chemotherapy, hormone therapy, or immunotherapy, address the underlying cancer and can help reduce further bone damage. Effective management of MBD requires a multidisciplinary approach, focusing on improving patients' quality of life and minimizing complications.