By Melicent Lavers-Sailly
Pain relief is an important clinical challenge for managing skeletal metastases (cancer that has spread to the bone). In 2016, an estimated 202,400 Canadians developed cancer. Metastatic bone disease occurs in 60 to 80 per cent of cancer patients, most frequently among those whose cancer originated in the breast, prostate, liver, and lung. In addition, 70 per cent of metastatic bone cancer patients develop at least one lesion in the spine.
Bone metastases can cause severe pain, bone fractures, spinal cord compression, and hypercalcaemia – all of which can degrade a patient’s quality of life. Studies indicate that the most frequent complaint for 79 per cent of patients with skeletal metastases is pain associated with the disease. That pain is usually progressive and significantly reduces quality of life.
The gold standard for palliative care of painful bone metastases is radiation therapy (RT); however, it does not work for everyone. RT reduces pain by half for only 40 per cent of patients with skeletal metastases; while 30 per cent will still be in pain. In addition, it can take anywhere from seven to 10 days for RT to start reducing bone pain, and may take up to six weeks before the patient feels the full effect.
Exposure to radiation is also a concern — it progressively degrades the strength, ductility, and toughness of the bone tissue leading to an increased risk of fractures. More specifically, conventional RT has been shown to increase the risk of vertebral compression fractures by five per cent, while SBRT (stereotactic body radiation therapy) can increase that risk by up to 39 per cent.
Health Canada recently licenced a procedure that promises to play a significant role in addressing the pain associated with bone metastases for these patients. Known as the OsteoCool™ Bone Radiofrequency Ablation system, it was designed, developed and is manufactured in Canada by Baylis Medical. Medtronic acquired the technology in 2015 and together they have partnered to further innovate the system.
RF ablation delivers targeted radio frequency (RF) energy consistently to a tumour, creating frictional heat that kills the cancer cells. The procedure is commonly used to target soft tissue metastases, but less widely used on bone cancer — and in particular spine metastasis —because of the potential risk of damage to nerve tissue and/or the spinal cord itself.
OsteoCool was specifically developed to maximize the ablation of bone metastasis. It is a minimally interventional technology that can be used in an operating room setting under sedation, or with a local anaesthetic.
Through a small incision, imaging is used to guide thin tubes (cannulas) to the affected site in the patient. Small, water-cooled, bi-polar probes are then inserted, and temperatures are increased up to 70°C at the distal tip for a pre-set time. Where required, cement can then be injected into the ablated area to stabilize the bone and reduce the risk of fractures.
When combined with RT, Radiofrequency Ablation has been shown to deliver greater pain relief in a shorter timeframe. Up to 95 per cent of patients with spinal tumours having both experienced a decrease in pain that was considered clinically significant; furthermore, opioid use decreased significantly at eight to 12 weeks. Complete pain response at 12 weeks was 16.6 per cent with RT alone, and 53.3 per cent with RFA + RT with no increase in analgesic intake.
The pain and discomfort associated with bone metastasis and spinal tumours have long presented a significant challenge for palliative care professionals. Fortunately, newer specialized technologies are proving effective in bringing relief to patients, and hopefully, improving their quality of life during an extremely difficult time in their lives.
Melicent Lavers-Sailly is the PR & Corporate Communications Manager at Medtronic Canada.
