ASTRO Guideline Update on Palliative Radiation for Bone Mets

Kristin Jenkins

February 21, 2017

An updated guideline on the use of palliative radiation therapy for bone metastases from the American Society for Radiation Oncology (ASTRO) continues to support pain relief equivalency between single- and multiple-fraction regimens based on new high-quality evidence.

The implications for practice remain unchanged from the original 2011 guideline, senior author of the new guideline, Carol Hahn, MD, confirmed in an interview. Dr Hahn is vice-chair of radiation oncology at Duke Cancer Center Wake County and professor of radiation oncology at Duke University Medical Center, Durham, North Carolina.

"Updated data analysis confirms that radiation therapy provides excellent palliation for painful bone metastases and that retreatment is safe and effective," Dr Hahn and other members of the guideline task force write in "Palliative Radiation Therapy for Bone Metastases: Update of an ASTRO Evidence-Based Guideline."

The online report was published in the January-February issue of ASTRO's Practical Radiation Oncology journal.

The updated guidelines continue to recommend four dosing schedules for external radiation therapy to treat previously unirradiated tumors: a single 8-Gy fraction of radiation therapy, 20 Gy administered in 5 fractions, 24 Gy in 6 fractions, or 30 Gy in 10 fractions.

Decisions about which evidence-based treatment options are best for individual patients should be left to clinicians, say the guideline authors.

However, in the same issue, authors of a commentary say the updated guideline isn't specific enough when it comes to single-fraction radiation therapy.

Conversely, the authors of an accompanying editorial insist the optimal fractionation regimen for an uncomplicated bone metastasis has yet to be determined and that the data don't support a "one-size-fits-all" approach, such as 8-Gy single-fraction radiation.

Both the editorial and commentary "reflect strong opinions," Dr Hahn told Medscape Medical News. She pointed out that hypofractionation is a huge change in the delivery of radiation and that ASTRO is also updating fractionation regimens for breast cancer as well as for prostate cancer.

"Radiation therapy has always been very evidence-based, and we have a lot of quality assurance processes. It's just been a matter of codifying it," she commented.

However, she indicated, reducing the number of fractionation options for bone metastases to 10 treatments from the previous 200 to 300 was no small feat. "As a society, getting down to 10 treatments is huge." Beyond that, "it's a clinical judgment," she added.

"Although adherence to evidence-based medicine is critical," the task force says in its report, "thorough expert radiation oncology physician judgment and discretion regarding number of fractions and advanced techniques are also essential to optimize outcomes."

Clinicians must consider a range of factors, they point out, including the patient's overall health, life expectancy, comorbidities, tumor biology, anatomy, and previous treatment.

The task force examined data from 20 randomized controlled trials, 32 prospective nonrandomized studies, and 4 meta-analyses/pooled analyses published between December 22, 2009, and January 7, 2015.

The data confirm that single-fraction radiation therapy "may be delivered to spine lesions with acceptable late toxicity," Dr Hahn and colleagues say. They conclude that a single 8-Gy fraction provides "noninferior" pain relief compared with more prolonged radiation therapy, making it "particularly convenient and sensible for patients with limited life expectancy."

Importantly, single-fraction radiation therapy can reduce "the additional burdens of time, travel and cost for the patient," noted Stephen Lutz, MD, chair of the task force and a radiation oncologist at Blanchard Valley Regional Health Center in Findlay, Ohio, in a statement from ASTRO.

There is a higher risk for retreatment "to the same painful site" with single-fraction radiation therapy compared with fractionated treatment, the guideline authors point out, adding that patients need to be told this in advance, when treatment options are discussed. A meta-analysis confirmed re-treatment rates of 20% for single fractionation and 8% for multiple fractionation.

There is no evidence that single-fraction therapy provides unacceptable long-term side effects or that it is associated with a higher risk for pathologic fracture than fractionated therapy, the guidelines authors note.

In fact, results from a secondary analysis of a Canadian study published online February 9 in JAMA Oncology show that a single dose of radiation significantly reduces pain and improves quality of life in a significant proportion of patients with painful bone metastases from a variety of cancers.

Despite this, many US centers are using more multiple-fraction than single-fraction treatments, Rachel McDonald, MD(C), lead author of that study, told Medscape Medical News in an earlier interview. McDonald is a medical student at the Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.

"The study provides an argument that you really only need one treatment to get good results," she said. Palliative treatment should be working toward prolonging survival as well as improving quality of life, "no matter how long a patient has left," she added.

In terms of pain recurrence, the guideline authors found evidence from one prospective randomized trial confirming that both peripheral and spine-based painful metastases can be successfully and safely palliated with retreatment that adheres to published dosing constraints.

However, a lack of high-quality data on advanced radiation therapy techniques, such as stereotactic body radiation therapy, led the task force to recommend that these techniques be used only on a clinical trial basis or in cases where the results can be recorded in a registry. They also conclude that the need for external-beam radiation therapy is not ruled out by surgery, radionuclides, bisphosphonates, or kyphoplasty/vertebroplasty.

In the accompanying commentary, Edward Chow, MBBS, from Odette Cancer Centre at Sunnybrook Health Sciences Centre, and colleagues call the updated ASTRO guideline "vague" because it doesn't recommend a particular treatment schedule for single-fraction radiation despite strong evidence supporting its safety and effectiveness.

"The message needs to be clearer and the bar needs to be set higher; otherwise, the adoption of SF RT [single fraction radiation therapy] will continue to suffer," they say.

Dr Chow and colleagues also say the recommendations don't mesh with the ASTRO Choosing Wisely campaign, which recommends against the routine use of more than 10 radiation fractions for palliation of bone metastases. The campaign also appears to suggest that a total of 30 Gy in 10 fractions "is perfectly acceptable treatment for uncomplicated bone metastases" unassociated with pathologic fracture or spinal cord or cauda equina compression, they point out.

Dr Hahn, who is also the lead on the working group for Choosing Wisely, acknowledged that, "What they're looking for is a stronger statement for single fractionation."

The task force not only provided an evidence-based "appropriate range of care" to give clinicians more flexibility when tailoring treatment to meet the needs of individual patient, she explained, they also made sure the door stayed open to new radiation treatment options.

"It becomes difficult to put together a guideline for quality measures when payers will only pay for one treatment," Dr Hahn told Medscape Medical News. "If we come out and say single-fraction radiation treatment is for this group, then payers may only pay for them. The issue is further complicated as we develop evidence demonstrating that more aggressive local therapy may impact patient's overall disease outcomes in the setting of oligometastatic disease."

The real challenge is determining which clinical situations are appropriate for which fractionation regimens, Dr Hahn emphasized. "Certainly for patients at or near end of life, single fractionation is completely appropriate, but single-fraction radiation treatment is also a reasonable option in any patient. It's an issue of clinical judgment and shared decision making with the patient, knowing that there may be a higher risk of retreatment in the future."

In the related editorial, Victor J. Gonzalez, MD, and Krisha Howell, MD, from the Department of Radiation Oncology at the University of Arizona in Tucson, say that the use of single-fraction radiation therapy in uncomplicated bone metastases may not be for all patients.

It "remains to be seen" whether a single 8-Gy fraction provides equivalent local control and prevention of pathologic fracture, write the editorialists. "In patients with a good prognosis and risk factors for local morbidity from disease progression, fractionated RT [radiation therapy] may be justified," they suggest, adding that until more studies are done, "hypofractionated palliative regimens may provide a safe and effective method of improving local control beyond that provided by [a single] 8 Gy/1 fx [fraction]."

In future, the limitations of existing data on equivalence between palliative regimens need to be acknowledged, Dr Gonzalez and Dr Howell say. Without this, they note, one may "be led…to believe that no clinical justification can be provided for the use of fractionated RT in the treatment of patients with uncomplicated bone metastases."

The ground has been moving under our feet. This will become less of an issue and almost an historical argument. Dr Carol Hahn

With alternate payment models "looming large," patterns of practice are going to change, Dr Hahn noted. "The ground has been moving under our feet. This will become less of an issue and almost an historical argument."

Even with different quality reporting standards, however, evidence-based care can still be held to these benchmarks and measures, she emphasized.

Dr Hahn and most of the guideline coauthors have disclosed no relevant financial relationships, but two coauthors reported financial relationships with companies: guideline coauthor Tracy Balboni, MD, MPH, reported a financial relationship with the Templeton Foundation, and coauthor Simon Lo, MB, ChB, reported financial relationships with Elekta, Accuray, and Varian.

Pract Radiat Oncol. 2017;7:4-12, 14-15, 16-18. Guideline full text, Commentary extract, Editorial extract

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