Use of Single Fraction Palliative Radiotherapy for Bone Metastases: Population Based Practice Patterns in British Columbia over a Five-Year Period
Presenter: Robert A. Olson
Presenter Affiliation: BC Cancer Agency, Prince George, BC, Canada; University of British Columbia, Vancouver, BC, Canada.
Bone metastases are a common occurrence in patients with cancer, with some cancers, such as breast, prostate and lung, being more likely to spread to bone. Depending on the number of bone metastases and symptoms (e.g. pain or fracture) different treatment options are available. Radiation therapy is an effective treatment option in the management of bone metastases, with the goals of care to relieve pain and prevent fracture.
There is abundant evidence that a single treatment (fraction) of palliative radiation therapy for bone metastases is just as effective as treatment with multiple fractions for immediate relief of pain. Multiple fractions of radiation are often more expensive and inconvenient, making the patient come daily over the course of one to two weeks. However, it has been shown that patients who receive a single fraction of radiation are more likely to need repeat treatment than patients treated with multiple fractions. As there are advantages and disadvantages to both treatment options, it is often up to the patient and physician to determine the optimal number of treatments. Despite this, treatment with a single fraction is uncommon in North America. There is significant discussion regarding the reason behind this, with physician compensation often brought up as a potential reason.
In this current study, done in British Columbia, Canada, the physicians are salaried, thus taking compensation out of the equation. This allows for exploration of other factors that may play a role in the decision making process. The authors reviewed 8,613 patients, and over 17,000 bone metastases, treated with radiation from 2007 — 2011 in British Columbia.
Overall the authors found a decrease in the use of single fraction radiation therapy over the time period of the study, from 49% to 47%. The authors were able to identify factors that were associated with the use of single fraction radiation. Specifically, they found that men were more likely to be treated with a single fraction, as were older patients. They also found a difference in single fraction use depending on the type of tumor, with bone metastases from breast cancer more commonly treated, and genitourinary cancers (e.g. prostate cancer), lung cancers and gastrointestinal cancers less commonly treated. Lastly, they found that the site of metastatic disease made a difference in the likelihood of single fraction use, with bone metastases to the spine and pelvis less likely to be treated as compared to arms, legs, or ribs.
Additionally, associations were noted with physician experience and location. They found that physicians with more experience were more likely to use a single fraction. They also found that there is significant variability between different cancer centers, suggesting there is a strong "culture" effect within each center, where radiation oncologists practice similar to their colleagues.
This study looked at factors that were associated with use of single fraction radiation therapy for bone metastases. One important finding was that the likelihood of single fraction radiation use depended on how often other physicians at the same center used a single fraction. Further research is needed to assess how to increase the use of single fraction radiation therapy for appropriate patients with bone metastases.