The proton therapy world came together for the 54th annual Particle Therapy Co-Operative Group (PTCOG) Conference in San Diego, California, last week. Some of the presentations highlighted mounting evidence of the treatment's clinical value for cancer care, while others aimed to chip away at defining the costly treatment's appropriate use.

Until the supply and demand of proton therapy levels out, consideration has to be made for the patients who stand to benefit the most from treatment. In many cases, that means children. The comparatively low dose of radiation exposure diminishes the likelihood of future complications. So a study at PTCOG showing the number of pediatric cancer patients receiving the treatment is rising steadily is good news.

This year's PTCOG conference was held largely in partnership with the Scripps Proton Therapy Center, a state-of-the-art pencil-beam facility in San Diego. The lead researcher on the pediatric findings was Dr. Andrew Chang, medical director of pediatrics at Scripps.

The number of pediatric patients treated with proton therapy rose by 36 percent between 2010 (465) and 2013 (722). Of the children who received the treatment in 2013, over half of them were under 10 years old and roughly a quarter of them were enrolled in multi-institutional registry studies.

"Children are particularly vulnerable to the late side effects of radiation exposure to normal tissue, including treatment-related chronic disease and secondary cancers," said Chang, in a statement. "So we view this as a positive sign that more children are gaining access to this more precise form of radiation delivery."

Proton therapy is gaining ground on a national — and global — scale. As more facilities begin treating patients and more outcomes are analyzed, the benefits continue to reveal themselves and the indications for treatment become clearer.

The case for patients with esophageal cancer is no different. Another presentation — led by Dr. Michael Chuong, an assistant professor of radiation oncology at the University of Maryland School of Medicine — showed that esophageal cancer patients have significantly fewer toxic side effects when treated with protons than other radiation therapies.

By looking at 600 clinical cases, Chuong and his team — including colleagues from the MD Anderson Cancer Center in Houston, Texas, and the Mayo Clinic in Rochester, Minnesota — found proton therapy caused fewer side effects when compared to two other forms of X-ray treatment.

The reductions were found in nausea, blood abnormalities, and loss of appetite. Those effects, as well as fatigue, and lung and heart problems, are common for patients undergoing esophageal cancer treatment.

Chuong told DOTmed News that his team's research is the first to illustrate the dosimetric value of proton therapy on the side-effect profiles for esophageal cancer. "It's exciting that we're now connecting the benefits of protons on treatment planning computers with the real world experience," he said.

Proton therapy is a costly procedure but as outcomes continue to justify its use, the treatment is becoming more and more common. Currently there are an estimated 14 facilities in the U.S., and several more under construction. Including one in Maryland, which is expected to treat 2,000 patients per year when it opens.

As more and more data is generated to illustrate the meaningful benefits of proton therapy, less traditional disease sites are beginning to accumulate their own bodies of evidence. For Chuong, seeing that trend emerge was one of the more exciting aspects of this year's PTCOG.