Particle beam radiation therapy (PBRT), also known as proton beam radiation, is considered by some as an advanced form of radiation treatment. It uses a particle accelerator to generate a beam of protons that can be targeted in three dimensions and more precisely deliver a high dose of radiation to a tumor while sparing, or reducing, the damage to surrounding healthy tissue and organs.
At least 29 institutes around the world are currently operating facilities for PBRT, including seven in the U.S. But is this form of radiation really the best and safest treatment choice?
The Agency for Healthcare Research and Quality (AHRQ; Rockville, Maryland) has just issued a comparative effectiveness report that, instead of answering the question, presents a list of new questions dictating the need for broader study.
It's the first in a series of oncoming reports from AHRQ with a new budget for comparative effectiveness studies that jumped from $15 million per year since the program started in 2005 to $50 million per year in 2009 when the new administration shined the spotlight on the need for more information to guide effective and cost-saving healthcare.
This new-style report, called a technical brief, is the agency's first in a series of rapid-turnaround reports that summarize key issues and highlight when more research is warranted.
"This was one of our technical brief studies that we've just recently started," Elise Berliner, PhD, director of AHRQ's technology assessment program, told Medical Device Daily. "For some topics not enough evidence exists to do a thorough review. This is a high-level review that looks at how many centers are involved, how many patients have been treated. We're trying to get that kind of overview information. The second part of report is a systematic literature scan."
The tech brief comes from a topic triage process now in place at AHRQ that occurs when any stakeholders nominate topics to be studied for comparative effectiveness.
"The most important finding is that the majority of studies that were done are single arm and there aren't that many comparative," she said. "They [study investigators] didn't use alternative care as a comparator. A lot of studies looked at different doses, but no studies compared with alternatives such as stereotactic therapy."
The conclusion: There are not enough well-balanced studies to draw a conclusion.
"We now hope that different stakeholders will consider the findings and hopefully more studies will be done," she said.
PBRT was first introduced as an experimental treatment in the 1950s, but it wasn't FDA cleared until 2001. And it's expensive. Each machine costs an estimated $175 million.
While the technical brief didn't conclude that particle beam radiation therapy is riskier than conventional radiation therapy, it highlighted the fact that there just isn't enough evidence to properly make an assessment.
"A large number of scientific papers on charged particle radiotherapy for the treatment of cancer currently exist," the report said. "However, these studies do not document the circumstances in contemporary treatment strategies in which radiotherapy with charged particles is superior to other modalities. Comparative studies in general, and randomized trials in particular [when feasible], are needed to document the theoretical advantages of charged particle radiotherapy to specific clinical situations."
Other conclusions from the report include:
• Most studies of PBRT have looked at its use in treating tumors that are inoperable or adjacent to critical body parts, such as tumors of the eye, head, neck, and spine.
• More than 60,000 people worldwide have been treated with PBRT since the 1970s.
• The current cost of building a PBRT facility in the U.S. ranges from $20 million to $175 million, depending on the size and scope of the facility.
• Evidence about the effectiveness and harms of PBRT compared with other cancer treatments is lacking.
Still River Systems (Littleton, Massachusetts) is currently developing the Monarch250 Proton Therapy System, while Varian Medical Systems (Palo Alto, California) acquired Accel Instruments (Bergisch-Gladbach, Germany) in 2007, a privately-held supplier of proton therapy systems for cancer treatment and scientific research instruments. Accel's technology for proton therapy incorporates a scanning beam technology that offers distinct performance advantages for more precise dose distribution than is possible with other proton delivery systems.
Earlier this year, the Centers for Medicare & Medicaid Services addressed a proposal to examine the possibility of covering PBRT for prostate cancer. One opponent of such an expansion of coverage is Mark Thompson, MD, of the Florida Radiation Oncology Group (Orange Park, Florida), who wrote in a letter to CMS that "the results in treating prostate cancer are no better than using intensity-modulated radiation therapy from an X-ray source or prostate brachytherapy, which cost a fraction of proton therapy." Thompson made the case that until the data for proton beam therapy "support superior results ... protons for prostate cancer should not be funded."
Leonard Artz, executive director of the National Association for Proton Therapy (NAPT; Silver Spring, Maryland) wrote a letter to CMS saying that "authoritative evidence does exist demonstrating that the benefits ... far outweigh any anticipated risks" thanks to the therapy's "greater precision" in terms of dosing area.
Another position was offered by the American Society for Radiation Oncology (Fairfax, Virginia) which recommended "that the coverage with study participation policy be applied" to a "comparative registry study [possibly with a parallel randomized clinical trial arm]," which "is likely to provide meaningful answers" on the safety and efficacy of PBT in this use (MDD, Feb. 2, 2009)
Future technical briefs will describe the evidence on fetal surgery, stereotactic surgery for non-brain cancers and percutaneous heart valves.
Lynn Yoffee; 770-361-4789