Cancer that begins in an organ, such as the lungs, breast, or prostate, and then spreads to bone is called metastatic bone disease (MBD).
Treatment options for MBD are often dependent upon where the bone metastases have developed. This article provides information on treatment options for specific areas of the skeleton. For a complete discussion of metastatic bone disease and its treatment:
Twenty percent of bony metastases occur in the upper extremity (shoulder, upper arm, and forearm), with approximately 50% of these in the humerus (upper arm). Upper extremity metastases can cause severe functional impairment, and can hinder personal hygiene, independent ambulation, the ability to use external aids, meal management, and general activities of daily living.
Treatment options include nonsurgical management (radiation, functional bracing, and medications, such as bisphosphonates), surgical stabilization, and surgical removal and reconstruction. Patients not suitable for surgery are those with limited life expectancy, other severe medical problems, small tumors, or tumors that can be treated with radiation alone. Radiation therapy can be administered alone or in combination with surgery. The goals of surgery are stability, functional improvement, and pain relief.
The location and extent of the metastasis dictates the treatment option. Metastatic lesions of the collarbone (clavicle) and shoulder blade (scapula) are generally treated without surgery. Some cases, however, require surgical intervention.
MBD of the upper humerus near the shoulder may be treated with a variety of techniques, depending upon how extensive the cancer is. Sometimes, a portion of the upper arm and shoulder needs to be replaced with an artificial metal prosthesis (upper humeral prosthetic replacement). Generally, it is only the arm side of the shoulder joint that is replaced when a patient has metastatic disease. The socket side of the joint is usually not involved.
These surgeries are generally more complex than the shoulder replacements used for shoulder arthritis, and MBD patients often have less function due to rotator cuff removal and reattachment to the metal prosthesis.
Humeral shaft tumors occur along the length of the bone, below the shoulder and above the elbow. They are also treated with a variety of techniques, although the joint generally does not need to be replaced. Bone cement (polymethylmethacrylate or PMMA) affords immediate stability, functional restoration, and supplements poor bone quality. Humeral rods inserted down the central canal of the bone span the entire humerus and provide both mechanical and rotational stability.
Sometimes, the tumor will be removed if it is not sensitive to radiation, but often it is left in place because radiation treatment can kill the tumor after the bone has been stabilized.
Segmental spacers (where the middle part of the bone is removed and replaced with metal) offer a reconstructive option for treatment of shaft lesions. They are used in large defects and cases of failed prior surgery due to progressive disease. Segmental spacers can be used after resection of the metastatic lesion, minimizing blood loss in bloody lesions and often alleviating the need for postoperative radiation.
Open stabilization with plates and screws is another treatment option for humeral shaft lesions, although less commonly used than intramedullary fixation. Open fixation requires a more extensive exposure of the humerus and limits the ability to protect the entire bone.
Mid-Arm (Near the Elbow)
Tumors located above the elbow can be treated with a variety of techniques. Flexible nails offer the ability to span the entire humerus, excellent functional recovery, and preservation of the natural elbow joint. Elbow replacement may be necessary if the tumor extends to the joint or involves the end of the humerus near the joint.
Metastatic lesions below the elbow are rare. The most common primary tumors that metastasize to this location are lung, breast, and renal cell carcinoma. Metastatic lesions in the radius and ulna can be treated with flexible rods, plates and screws, or bracing. Lung cancer is the most common primary tumor that metastasizes to the hand.
Patients with lower extremity metastasis have concerns related to pain and ability to walk. Fractures are more common and the surgical techniques to stabilize the bones are becoming more standardized.
Pelvis and Acetabulum (Hip)
The indications for surgical intervention in the pelvis are failed nonoperative management, actual or impending fractures, and significant involvement of the hip joint cup (acetabulum), and other critical mechanical portions of the pelvis. If the acetabulum is involved, hip replacement (total hip arthroplasty) is generally necessary.
Like shoulder replacements, hip replacements for tumors are more complicated than routine hip replacements. Surgically related problems occur in approximately 20% to 30% of cases.
The femur (thighbone) is the most likely long bone to be affected by metastatic bone disease. The upper third is involved in 50% of cases. Because the development of bone metastasis is a dynamic process, it is important to stabilize as much of the femur as possible.
Femoral Head and Neck
Hip or femoral head and neck lesions, whether impending or actual, rarely heal. The procedure of choice is joint replacement. The indication for partial (hemiarthroplasty) versus total hip reconstruction is a function of acetabular or hip cup involvement.
Lower Hip (Peritrochanteric)
Placement of a metal rod down the central canal of the femur in this location has been more successful than screw and side plate implants. Sometimes, the area is so badly destroyed that the surgeon must replace the region with a special hip replacement, especially if the metastatic bone disease is not sensitive to radiation treatment.
Below the Hip (Subtrochanteric)
The subtrochanteric area of the femur is subjected to forces four times to six times body weight. For this reason a substantial percentage of subtrochanteric pathologic fractures will not heal. Screw and side plate constructs, along with PMMA, can be used in this area, but have a relatively high failure rate. Upper femoral replacement may be necessay in extreme cases where the bone is badly destroyed. For lesions where a break has not yet occurred but is likely, use of a metallic nail is the ideal option.
Tumors in the shaft of the femur can be treated with plates and PMMA, or by placement of a metal rod down the central canal of the bone. Fractures are usually best treated with a rod.
Distal Femoral (Supracondylar)
Lower end femur (supracondylar) lesions can be a challenge to treat secondary to multiple bone fragments and poor bone quality. Generally, good function can be obtained with a metallic implant, but when the bone is badly destroyed, the end of the femur and the knee may need to be replaced. This form of knee replacement is usually more involved than the knee replacements for arthritis.
Metastasis to the shinbone (tibia) is far less common than the femur. For lesions in the upper tibia, the approach is generally similar to that of the lower femur. Often, good function can be obtained with cement, plates and screws, but if the bone is badly destroyed the upper end of the tibia and the knee joint may need to be replaced. For tibial shaft lesions, a metal rod is usually placed down the central canal of the bone. When the far end of the tibia is involved, various techniques can be employed, but generally plates and screws augmented with bone cement are advised.
Less than 1% of all bone metastasis involve the foot. The most common types are lung, kidney, and colon. Treatment should be individualized and employ a combination of radiation therapy, orthotics, and limited surgery.
Metastatic bone disease commonly spreads to the spine. Only the lung and liver are more frequently involved.
Most cases of metastatic bone disease to the spine do not need surgery. The presence of pain, the risk of developing a fracture, nerve compression, and response to noninvasive or systemic treatments must be considered in the decision as to whether surgery should be performed.
If the patient has pain but no nerve damage or risk of fracture, radiation treatment is preferred. If the patient has a tumor that is responsive to radiation, radiation can be used emergently, even if there is neurologic compromise. The response is usually sufficiently quick that the risk of permanent nerve damage is no higher than that seen after surgery.
Over the past decade, minimally invasive or percutaneous techniques for metastatic bone disease to the spine have been developed. Treatment of this type is used to control pain in patients who have developed certain types of fractures.
One technique, vertebroplasty, involves percutaneous direct injection of bone cement, or PMMA through the back. A more recent development, kyphoplasty, is a means of restoring normal spine alignment before injecting PMMA. The Food and Drug Administration has not approved PMMA for this indication, and therefore this is considered an "off label" use of PMMA. Nevertheless, surgeons at major cancer centers are using this technique with great success in select patients with metastatic bone disease to the spine.
Surgery is indicated for advanced cases of metastatic bone disease to the spine. Patients with intermediate involvement who have continued pain after radiation may be indicated for surgical intervention.
This article provides information on treatment options for specific areas of the skeleton. For a complete discussion of metastatic bone disease and its treatment:
The American Academy of Orthopaedic Surgeons
9400 West Higgins Road
Rosemont, IL 60018