Nov. 1, 2012 (Boston) -- A pricey new treatment for prostate cancer called proton beam therapy appears to cause slightly less diarrhea, bloating, and cramping than traditional radiation treatments. But the effect is short-lived, a new study suggests.
The findings come from a review of questionnaires filled out by men who underwent one of three forms of radiation therapy, so the results are far from conclusive.
But even though proton beam therapy's effectiveness and safety has yet to be proven, more and more men are opting for the treatment. The number of treatments has climbed steadily in the last five years and is expected to double in the next three years, says researcher Phillip J. Gray, MD, a resident in the Harvard Radiation Oncology program in Boston.
"Patients say proton beam therapy sounds so much better, they want it no matter what the cost," says Colleen Lawton, MD, a radiation oncologist at the Medical College of Wisconsin Clinical Cancer Center in Milwaukee.
"We don't know if it is less toxic. We don’t know if it is more effective. All we do know is that it is more costly."
Lawton, who was not involved with the research, moderated a news briefing to discuss the findings here at the annual meeting of the American Society for Radiation Oncology (ASTRO).
In proton beam therapy, beams of protons are targeted directly to tumors, thereby sparing healthy tissue, which theoretically should cause fewer side effects. Indeed, its benefit in treating eye and pediatric brain tumors is well documented. But for prostate cancer, the answer is far less clear.
So Gray and colleagues studied three groups of men: 94 who got proton beam therapy, 153 who were treated with what's called intensity-modulated radiation therapy (IMRT), and 123 who were treated with an older form of external beam radiation that IMRT has replaced over the past decade.
Internal radiation therapy (also known as brachytherapy) was not included in this study.
IMRT also delivers its radiation with extremely high precision, thereby reducing the risk that it will hit surrounding healthy tissue -- but in this case the cargo is X-ray radiation, not protons.