Data lacking on charged-particle radiation therapy compared with conventional treatment

Currently published studies on charged-particle radiation therapy lack sufficient data comparing the therapy to other modalities, and researchers are calling for comparative, randomized trials to document the advantages of charged-particle radiation therapy in specific situations.

The researchers set out to review the benefits and harms of charged-particle radiation therapy and searched for published studies from Medline, manufacturer websites, treatment centers and professional organizations. They identified 243 eligible articles that described clinical outcomes or adverse events in 10 or more patients with cancer treated with charged-particle radiation therapy.

In these studies, charged-particle radiation therapy was used alone or in combination with other interventions for common types of cancer, such as lung, prostate or breast, and uncommon types, including skull-based tumors or uveal melanomas. One hundred eighty-five of these articles were single-group retrospective studies.

Eight randomized and nine nonrandomized trials compared treatments with or without charged-particle radiation therapy. None of these comparative studies reported statistically significant differences in OS or cancer-specific survival, or in serious adverse events. The researchers also noted that none of the trials had a sufficiently large sample size or sufficient duration of follow-up.

In three of four trials that reported statistically significant differences in outcomes other than survival, data favored the charged-particle radiation therapy group or the group with the most intensive intervention. However, the fourth trial revealed a higher incidence of rectal bleeding with charged-particle radiation therapy than with the conventional approach in patients with prostate cancer (12% vs. 32%; P=.002).

“The few available randomized trials mainly assessed intermediate outcomes. Investigators frequently compared lower and higher doses of the same charged particles, and they rarely compared this type of radiation therapy with other treatment modalities,” the researchers wrote. “Studies comparing charged-particle radiation therapy strategies with contemporary alternatives that do not include charged-particle radiation therapy would be more informative.”

Terasawa T. Ann Intern Med. 2009;151.