Study: More evidence needed on value of particle-beam radiation therapy
Particle-beam radiation therapy is considered by some clinicians to be better than traditional radiation therapy, but there is limited evidence about its safety compared with other types of radiation therapy, according to a literature review published Sept. 14 online ahead of print in the Annals of Internal Medicine.

Teruhiko Terasawa, MD, from Tufts Medical Center in Boston and colleagues reviewed evidence about the benefits and harm of charged-particle radiation therapy.

"As technologies develop and new clinical interventions arise, it is important to balance access to potentially beneficial new technologies with ongoing research and evaluation to determine whether the technologies deliver what they promise," said Carolyn M. Clancy, MD, director of Agency for Healthcare Research and Quality (AHRQ), which provided the primary source of funding for the study.

The investigators searched MEDLINE for relevant publications in English, German, French, Italian, and Japanese. Web sites of manufacturers, treatment centers and professional organizations also were searched for relevant information.

Four reviewers identified studies of any design that described clinical outcomes or adverse events in 10 or more patients with cancer who were treated with charged-particle radiation therapy. The four reviewers extracted study, patient and treatment characteristics; clinical outcomes; and adverse events for non-overlapping sets of articles. A fifth reviewer verified data on comparative studies.

Particle-beam radiation therapy was introduced as an experimental treatment in the 1950s, but was not cleared for widespread use by the FDA until 2001. According to AHRQ, the technology is "very expensive—an estimated $175 million for each device—and is usually only available in large academic medical centers."

Currently, seven centers in the United States have facilities for particle-, or proton-beam radiation, and at least four are under construction, each costing between $100 and $225 million, according to the authors.

In 243 eligible articles, Terasawa and colleagues found that charged-particle radiation therapy was used alone or in combination with other interventions for common (for example, lung, prostate or breast) or uncommon (for example, skull-base tumors or uveal melanomas) types of cancer. Of 243 articles, 185 were single-group retrospective studies.

Eight randomized and nine nonrandomized clinical trials compared treatments with or without charged particles. Also, the researchers reported that no comparative study reported statistically significant or important differences in overall or cancer-specific survival or in total serious adverse events.

The studies found did not indicate that particle-beam radiation therapy is riskier than conventional radiation therapy. However, most studies about the therapy were conducted on small numbers of patients and did not compare the safety of particle-beam radiation therapy against other therapies.

“For many cancers other than head and neck cancers, there are not enough comparative studies in the literature to base an evaluation of the clinical or cost effectiveness of particle-beam radiation therapy compared with other treatments,” according to the AHRQ.

As a result, the authors said that evidence on the comparative effectiveness and safety of charged-particle radiation therapy in cancer is needed to assess the benefits, risks and costs of treatment alternatives because the few published studies “do not document the circumstances in contemporary treatment strategies under which radiation therapy with charged particles is superior to other modalities.”