Ten years after treatment, only 7% of men who received a boost of proton therapy suffered a recurrence of their prostate cancer, compared with 31% of men who received conventional doses of radiation.
"Importantly, there were no differences between the groups in terms of the urinary or bowel function side effects" most commonly associated with radiation therapy, says researcher Carl Rossi Jr., MD, associate professor of radiation medicine at Loma Linda University in California.
"This first-of-its-kind study provides evidence of the benefits of [proton beam therapy]. It is safe, effective, and has minimal side effects," he tells WebMD.
The findings were presented at the annual meeting of the American Society for Radiation Oncology.
Proton Beam Therapy for Prostate Cancer Spares Healthy Tissue
Proton beam therapy is a form of radiation treatment that uses protons rather than conventional photon X-rays to treat certain types of cancer and other diseases.
The beauty of the treatment, Rossi says, is that it spares normal, healthy tissue from radiation.
"We have exquisite control over where the radiation goes [in the body]. And because we can target the radiation right to the site of the tumor, we can use much higher doses of radiation than we can with conventional therapy," he says.
"The Holy Grail of radiation oncology is to deliver more radiation to the target and spare healthy tissues and organs," says Farzan Siddiqui, MD, PhD, a radiation oncologist at Henry Ford Hospital in Detroit.
"This is the promise we are seeing with proton therapy," says Siddiqui, who was not involved with the research.
Proton Therapy for Prostate Cancer Safe
A second study presented at the meeting confirmed the safety of the technique.
Researchers followed more than 200 men for at least one year after they received proton therapy for prostate cancer.
Only two men suffered serious side effects, and they both had conditions that predisposed them to those problems, says Nancy Mendenhall, MD, a professor of radiation oncology at the University of Florida in Jacksonville.
Only about six medical centers in the United States have proton therapy capabilities, but several other facilities are opening in the near future, she tells WebMD.
Although the treatment can be expensive -- up to 50% more than conventional radiation therapy -- Mendenhall says she expects costs to come down as availability rises.