Metastatic Bone Tumor – Metastatic Bone Disease
When cancer spreads (metastasizes) there are places in the body that it metastasizes to – lungs, liver, brain, and bones. This spread can occur before someone has been actually diagnosed with cancer or it can occur years after treatment if the cancer cells are still in the body and the cancer returns. When the spread is to the bone, the tumor in the bone is called a metastatic bone tumor and treating physicians may describe this as metastatic bone disease as well as “bone mets”. There are some types of cancers that are more likely to metastasize to the bone.
There are blood cancers that also cause bone lesions. These blood cancers include – multiple myeloma, and lymphomas.
The most common sites of bone metastases are1:
- Upper arm (humerus)
- Thigh bone (femur)
- Shin bone (tibia)
Symptoms of Metastatic Bone Tumors
Metastatic bone tumors weaken the bone in the area where they are located. They do this by either destroying the bone (osteolytic tumors) or by causing abnormal bone to form (osteoblastic tumors). These weak areas in the bone are quite painful, and are prone to fracture. If a fracture does develop in the area of the “bone met” it is referred to as a pathologic fracture. Bone lesions in the vertebral body of the spine can fracture as well, this type of pathologic fracture is called a compression fracture because the vertebra collapses (or compresses).
The tumors develop in the part of the bone marrow that produces red blood cells. Because the metastatic lesions can decrease the red blood cell production, a patient with metastatic bone disease can become anemic. 2
Diagnosing Metastatic Bone Tumors
When cancer is first diagnosed, a patient will undergo PET/CT scans, MRIs and other tests specific to the type of cancer. Metastatic bone lesions may be found during this staging process.
An X-ray of the area of the patient’s pain will show a destructive area in the bone.
A CT scan may be requested to evaluate the extent of the bone lesion and if there are any fractures that the x-ray doesn’t show.
A bone scan will likely be ordered to determine if there are other bones affected that haven’t started causing pain yet.
An MRI may be requested to see if there is expansion of the lesion into the soft tissue around the tumor.
A biopsy of the lesion will be done to determine if the tumor is a metastatic lesion from the original type of cancer or if it is from a new type of cancer.
Treatment of Metastatic Bone Tumors
Because metastatic bone tumors are both painful, and place someone at risk of a fracture, treatment focuses on minimizing the pain and addressing the chance of a fracture. In some situations managing pain with medications and activity limitation is appropriate. When there is a fracture already in the area, or if there is a high likelihood of a fracture, surgery may be recommended along with pain management.
Surgery for lesions in the extremities usually involves putting a metal plate on the bone where the tumor is located, which stabilizes the bone. If a lesion is in the vertebral body, a procedure where bone cement is injected into the lesion (kyphoplasty or vertebralplasty) is done. This minimizes the possibility that the vertebral body will collapse.
Radiation therapy has been effective in helping to control the pain associated with metastatic bone tumors. A short course of radiation may be prescribed, with the radiation directed at the lesion.3 There are medications called bisphosphonates that can help to prevent the bone damage caused by metastatic tumors. Bisphosphonates appear to work by decreasing activity of the bone destroying cells (osteoclasts) which slows the bone destruction. In addition, patients who take these medications describe some pain relief while taking the medication.4
1. Vigorita, Vincent (2007). Orthopaedic Pathology. Lippincott Williams & Wilkins. p. 52
2. Coleman RE (October 2006). "Clinical features of metastatic bone disease and risk of skeletal morbidity". Clin. Cancer Res. 12 (20 Pt 2): 6243s–9s
3. Palliative Radiotherapy for Bone Metastases: An ASTRO Evidence-Based Guideline (2011)
4. Van Poznak CH, Temin S, Yee GC, et al. American Society of Clinical Oncology executive summary of the clinical practice guideline update on the role of bone-modifying agents in metastatic breast cancer. J Clin Oncol. 2011;29(9):1221-7