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Advances in the Treatment of Cancer Metastatic to Bone

Marc Isler, M.D., FRCSC
Montreal, QC

With increasing age, the prevalence of cancer continues to rise in the Canadian population. According to the National Cancer Institute of Canada, about 40% of Canadians will develop cancer and, roughly, 25% of them will die of their disease. With newer medical treatment, more patients will present with extensive bone metastases without advanced visceral disease.

It is crucial that long-term planning reflects this reality and that the medical community recognizes the importance of early detection of such pathology to allow for timely referral. In an optimal multidisciplinary setting, orthopaedic surgeons can make a significant difference in the quality-of-life for selected cancer patients.

 

Alternative Newer Treatments

Vertebroplasty & Kyphoplasty
These techniques are usually considered for pain in a neurologically stable patient with known cancer, especially in a setting where prior radiation and or chemotherapy has been administered.

These two techniques are different in that vertebroplasty involves direct injection of cement under pressure into a vertebral body (tumour), whereas in kyphoplasty, balloon inflation tends to correct the kyphosis and creates a space for subsequent low pressure cement injection. Both are done with a transpedicular approach either guided by CT imagery or as a mini-open procedure under fluoroscopy, and both involve the risk of displacing tumour into the adjacent spinal canal or into enlarged venous structures. The risk of cement being injected accidentally into the spinal canal is considered to be lesser in kyphoplasty as low pressure cement injection is used.

Currently practiced for osteoporosis and multiple myeloma, some centres have used these techniques for other forms of cancer. It is too soon to assert clear guidelines for these techniques but an expert in this technique should ideally be part of a complete oncological group so that a consensus can be developed.

Acetabuloplasty
In combination with multimodality medical and radiation treatment, including embolisation, percutaneous curettage and cementation under image intensification (similar to vertebroplasty) can provide suprisingly good results and presents a low rate of complication.

Radio Frequency Ablation
A new trend in minimally invasive control of pain associated with bone metastases is percutaneous radiofrequency ablation, using a hybrid of the techniques used for osteoid osteoma and those used for hepatic metastases. So far the rate of complication is low, the success rate is sufficiently good to pursue use of this technique and the challenge will be to define which patient will benefit. This technique, though not expensive, is unavailable in many centres.

Percutaneous Cryotherapy
Even more recently, percutaneous use of cryotherapy has been used for various bone lesions in patients too sick to support classic surgical treatment, with encouraging results. As with radio-ablation, it is too soon to conclude on clear indications for the technique.

VAC
Orthopaedic oncologists and trauma surgeons have found that vacuum-assisted closure is a valuable tool to prevent or treat soft tissue complications of surgical treatment. It can be used in treatment of metastatic disease, particularly when wound dehiscence or hematoma complicates surgery. Not only can it decrease the incidence of infection and hasten healing so that the patient can rehabilitate more quickly, but it decreases the frequency of dressing changes and can be applied in the home care setting so important to the patient with advanced cancer.

Biphosphonates and Other Medical Adjuvants
Major benefits in survival and quality-of-life have been shown with the use of biphosphonate therapy in multiple myeloma, and to a lesser extent with other cancers. This has resulted in a decrease in surgical intervention. Chemotherapy, hormonal therapy and newer drugs to target cellular signaling mechanisms (such as Gleevec) have also had an impact.

Early Detection
Better organization of the infrastructural aspects of cancer care are a goal of many provinces and it is thought that, as with prevention and early detection, the outcome of patients with cancer metastatic to bone will improve. First, better education and communication are predictable results of multidisciplinary management, and furthermore optimal therapy is defined and improved through well organized clinical trials.

Careful monitoring of patient evolution including screening for metastases is facilitated when multimodality medical protocols are offered. These, in turn, offer windows of opportunity to intervene with less invasive and morbid techniques of skeletal reconstruction, before significant deterioration of function occurs.

Conclusion
Cancer is increasingly being recognized and managed as a chronic disease and in this light, the cost-effectiveness of early and evidence based management may allow us to preserve rather than reconstruct bone stability in the presence of metastastic disease.

Related Reading

  1. National cancer institute of Canada; statistics URL: http://www.ncic.cancer.ca

  2. Sim F.H. Diagnosis and management of metastatic bone disease. A multidisciplinary approach. New York: Raven Press; 1988.

  3. Talbot M., Turcotte R.E., Isler M., Normandin D., Iannuzzi D., Downer P. Function and health status in surgically treated bone metastases. Clin Orthop 2005.

  4. Mirels H. Metastatic disease in long bones: a proposed scoring system for diagnosing impending pathologic fractures. Clin Orthop; 1989:249:256-64.

  5. Damron T., Morgan H., Prakash D., Grant W., Aronowitz J., Heiner J. Critical Evaluation of Mirels' Rating System for Impending Pathologic Fractures