The American Society for Radiation Oncology (ASTRO) has issued evidence-based guidelines for the use of palliative radiotherapy to treat bone metastases.
Developed by an ASTRO-appointed task force of 17 radiation oncology experts from the U.S., Canada, and the U.K,. the guidelines are based on the findings of 25 randomized clinical trials, 20 prospective single-arm studies, and four meta-analyses published in peer-review journals from 1998 through 2009. The task forced deems electron-beam radiotherapy the mainstay for treating bone metastases, with the most common fractionation schemes encompassing a single 8-Gy fraction, 20 Gy in five fractions, 24 Gy in six fractions, and 30 Gy in 10 fractions. All are said to provide comparable initial relief, and treatment in a single-fraction session is said to offer the advantages of more efficient treatment for both patient and caregiver, at a lower overall cost. The need for repeat treatment was pegged at 12% higher than when multiple treatments are performed, at a repeat rate of 20% and 8%, respectively. No long-term side effects from single-fraction treatment are specified.
The guidelines also stipulate that repeat irradiation with electron-beam radiotherapy might be feasible in some circumstances, although the details of its effectiveness and safety are still to be determined. Caution is recommended when repeat treatment would include the spinal cord, as is first treating these within the available clinical trial before subjecting them to an electron-beam radiotherapy regimen. Stereotactic body radiotherapy can, according to the guidelines, be considered for patients with a tumor in the spinal column or paraspinal areas, but they should be entered into an appropriate clinical trial, and stereotactic body radiotherapy should not be the primary treatment of vertebral bone lesions causing spinal cord compression.
Additional recommendations contained within the guidelines state that while bisphosphonates act effectively when combined with electron-beam radiotherapy, no patient should receive bisphosphonate treatment alone and that large prospective randomized trials should be conducted to determine the most effective protocol for this combined treatment. Use of radionuclides is deemed most appropriate for patients who have several sites of painful osteoblastic metastases that cannot be conveniently or safely tre,ated with electron-beam radiotherapy. The guidelines also call for surgical decompression, and stabilization plus postoperative radiation therapy, to be considered for some patients with single-level spinal cord compression or spinal instability.
Complimentary copies of the complete set of guidelines are available by sending an email to communications@astro.org.
