Cancer spread to the spine: Predictors of survival

This study examined predictors of survival for cancer patients with spinal bone metastases. Authors reported that stable and unstable spinal bone metastases had similar survival rates. However, factors predictive of survival were different between groups.

When cancer spreads outside of the breast (known as metastatic breast cancer), tumors can form in distant parts of the body. One site of metastatic breast cancer is on the bone. Bone tumors can cause significant pain and other complications such as fractures or nerve compression. Bone metastases are frequently located along the spine. Spinal bone metastases can be stable with intact vertebrae (spinal backbones) or unstable with collapsed vertebrae. The treatment and prognosis of stable and unstable spinal bone metastases can differ. Identifying factors that can predict survival plays an important role in the treatment decision for patients with spinal bone metastases.

This study analyzed the records of 915 cancer patients with spinal bone metastases. Most patients included had lung, breast, or kidney cancer as the primary tumor. All patients received radiation therapy to the spinal bone tumors. 62% of patients had bone tumors in the middle part of the spine. 38% had bone tumors in the lower part of the spine. 49.7% of patients had unstable spinal bone metastases (SBM). Patients were followed for an average of 12.2 months.

2-year overall survival rate (proportion who have not died from any cause since treatment) was 42% for stable SBM and 38% for unstable SBM. Bone survival (time between first diagnosis of bone metastases until death) was also similar between groups. Bone survival for stable SBM was 57% after 6 months, 22% after 2 years, and 8% after 5 years. Bone survival for unstable SBM was 59% after 6 months, 19% after 2 years, and 8% after 5 years.

Male gender, high functional impairment, and lung cancer were associated with shortened bone survival for stable SBM. Older age, high functional impairment, multiple bone tumors, lung cancer, and wearing an orthopedic corset were all associated with shortened bone survival for unstable SBM. Previous chemotherapy, localization of bone tumors on the spine, and radiation therapy schedule did not affect bone survival.

Authors concluded that stable and unstable spinal bone metastases had similar survival rates. However, factors predictive of survival were different between groups.