When cancer cells spread through the body and invade a patient's
bones, these new lesions are known as bone metastases. Many different
types of cancer can spread to the skeletal system, including breast,
prostate, lung and rectal cancers, and bone metastases may occur months
or even years after an original cancer diagnosis.
Treatment of these
malignancies aims to provide relief for symptoms, such as pain and
spinal cord compression, and to suppress local disease. Radiation therapy, also known as radiotherapy, is a safe and
effective option to relieve symptoms associated with bone metastases.
‘The American Society for Radiation Oncology (ASTRO) recently published an updated clinical guideline that underscores the safety and effectiveness of palliative radiation therapy (RT) for treating painful bone metastases.’
The American Society for Radiation Oncology (ASTRO) recently
published an updated clinical guideline that underscores the safety and
effectiveness of palliative radiation therapy (RT) for treating painful
Based on recent clinical trial data, the guideline
recommends optimal RT dosing schedules for pain relief, including
options for re-treatment. The guideline, "Palliative radiation therapy for bone metastases: Update of an ASTRO Evidence-Based Guideline," is available as a free access article in Practical Radiation Oncology
, ASTRO's clinical practice journal.The updated guideline maintains the four previously recommended dosing
schedules for external RT to treat previously unirradiated tumors: a
single 8 Gray (Gy) fraction of RT; 20 Gy administered in five fractions;
24 Gy in six fractions; or 30 Gy in 10 fractions. Research indicates
that patients experience similar pain relief and toxicity rates with
each of the fractionation options.
Although clinical trials have cited
higher retreatment rates for patients who received single-fraction RT,
the convenience of this option may make it the optimal choice for
patients with limited life expectancy. A recent analysis of clinical trial data published in JAMA Oncology
recommended that "a single 8-Gy radiotherapy dose for bone metastases
should be offered to all patients, even those with poor survival."
Greater adoption of the single-fraction approach - which requires
only one visit - also may reduce the disparity between the number of
patients who would benefit from this therapy and the markedly small
number who actually receive it. Surveys of palliative care
professionals indicate that the vast majority consider RT an important
and effective component of hospice care but do not actually refer many
of their patients for the therapy. In one study,
for example, 88% of hospice professionals said that painful bone
metastases merited referral for palliative RT, but only 3% of
hospice patients nationwide actually received the treatment. Barriers
including cost, transportation and length of treatment were cited as key
reasons for underutilization.
"Decades of research and many clinical trials have established that
radiation therapy provides safe, effective and quick pain relief for
patients suffering from bone metastases," said Stephen Lutz, FASTRO,
chair of the task force that developed the guideline update and a
radiation oncologist at Blanchard Valley Regional Health Center in
Findlay, Ohio. "Moreover, this relief can be achieved in as little as a
single fraction, which alleviates the additional burdens of time, travel
and cost for the patient."
In addition to primary treatment, the guideline also addresses
retreatment of bone metastases. It recommends that reirradiation should
be considered if patients experience recurrent or persistent pain more
than a month following external-beam radiation therapy (EBRT) to treat
peripheral bone metastases or spine lesions. Research demonstrates
moderate effectiveness for reirradiation; a 2014 systematic review and
meta-analysis found an overall pain response rate of 58%.
The guideline also considers the role of advanced RT techniques,
such as stereotactic body radiation therapy (SBRT), in primary treatment
and retreatment of painful bone metastases. SBRT uses sophisticated
imaging techniques to deliver a highly targeted, escalated dose of
radiation to the tumor and to limit damage to the surrounding tissue.
This precise targeting is particularly important for tumor sites near
multiple surrounding organs, such as the lung or prostate, or complex
sites, such as the neural system.
While emerging evidence points to the potential of SBRT to treat
spinal metastases, research in this area is limited compared with the
data supporting EBRT. Accordingly, the guideline recommends that the use
of advanced RT techniques for primary treatment or retreatment of
spinal lesions should be considered only in clinical trial or registry
settings. It also recommends that physicians consult the current ASTRO white paper on SBRT to inform their treatment decisions.
The guideline was based on a systematic literature review of studies
published from December 2009, the last date that was searched for the
original 2011 guideline, through January 2015. A total of 414 abstracts
were retrieved from PubMed, and the 56 articles that met inclusion
criteria (including 20 randomized controlled trials, 32 nonrandomized
prospective studies and four meta-analyses or pooled analyses) were
abstracted into evidence tables and evaluated by an eight-member expert
panel of radiation oncologists and topic experts in metastatic disease.
The clinical practice statement was approved by ASTRO's Board of
Directors following a period of public comment.