STUDY PROMOTES SAFE PRACTICE OF NEWER RADIATION TREATMENT

Toronto, ON (August 20, 2013) - In the first and largest multi-institutional experience of spine SBRT (stereotactic body radiotherapy), a newer and more targeted radiation treatment for cancer that has spread to the spine, Sunnybrook researchers recommend ways to safeguard patients from the adverse event of vertebral compression fracture (VCF) and clinically validate predictive factors most crucial to identifying those at high risk, as published in the Journal of Clinical Oncology.

Spine SBRT, also known as spine stereotactic radiosurgery, is a high precision and image-guided type of radiation treatment for spine metastasis. Unlike regular radiation therapy, very high doses are delivered over 1 to 5 treatments with the aim to ablate tumours while keeping the dose safe to the nearby spinal cord. However, the collateral damage within the healthy bone of the diseased vertebral body is an issue that has been previously unknown. VCF or fracture of the spine is a serious adverse event with the potential for patients to require surgery and increase dependence on pain medications.

"SBRT is an effective treatment that has emerged as a result of the fast pace of technological advances in radiation therapy, and is rapidly being adopted into mainstream clinical practice. Clinicians need to gain a greater understanding of the risks and protective strategies for related adverse events so we can continue to ensure safety and quality of life for patients after treatment," says lead investigator and Sunnybrook Odette Cancer Centre radiation oncologist, Dr. Arjun Sahgal, who is one of the pioneers of spine SBRT in Canada and internationally, and a leading proponent of quality and safety in this technique.

For overall risk stratification, the researchers report the risk of VCF significantly increased beyond 19 Gy per fraction and highest in those patients treated with 24 Gy per fraction or more. They recommend caution when treating patients with high dose per fraction SBRT and recommend a dose per fraction under 20 Gy (risk of VCF approximately 10 percent), especially in those patients with lytic tumour in the vertebral bone, spinal misalignment and early or baseline VCF. A recommendation for frequent follow-up also resulted from the study as the researchers found 64 percent of VCFs occurred within the first 4 months after treatment. 

"We hope this study will help practitioners determine patients most suitable for spine SBRT and patients who should potentially first undergo a surgical procedure to render the spine stable before high dose radiation is delivered," says Dr. Sahgal, associate professor, Department of Radiation Oncology, University of Toronto.

The researchers also used the Spinal Instability Neoplastic Score (SINS), a Canadian-developed tool that helps identify patients at greater risk of spinal instability and imminent collapse. They report three of the original six SINS criteria - baseline VCF, lytic tumour and misalignment - were critically predictive.

The researchers analyzed a major sample size of 410 tumours with 57 VCFs. This study was the result of a North American collaboration between Sunnybrook's Odette Cancer Centre, University of Toronto, Cleveland Clinic and MD Anderson Cancer Center.

About 30 percent of all cancer patients will develop metastasis or spread to the spine from, breast, colon, prostate or other cancers.

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