By Brendon Nafziger
The first hospital-based proton therapy center in the United States, at Loma Linda University in southern California, was recently renamed to honor the man who helped launch the site in 1990: Dr. James M. Slater. Slater, a radiation oncologist, recently spoke to DOTmed News about new directions for proton technology and why it needs to become more competitive with conventional radiation therapy.
Proton therapy is typically used to treat cancer, but Slater envisions a new frontier: central nervous system disorders. To start, his team is looking to treat epilepsy to help both young children who suffer from severe forms of the disease and veterans who developed epilepsy as a result of head injuries during their time in the service.
But epilepsy presents a two-fold problem. First, the team has to develop an advanced imaging technique, likely using PET/CT in conjunction with MRI, to pinpoint the origin of the abnormal signals in the brain that cause muscle contractions. Then, the team has to develop a technique for precisely ablating it using protons.
“We can tell from EEGs and other ways roughly where (the signal source) is, but not near well enough to treat with a very small beam,” Slater says. “That’s why we’re working on imaging in one lab, and another is working on making the beam shape and design.”
Slater envisions one-day treatments for most patients, as the brain structure needing to be destroyed is likely much smaller than most tumors. But Slater says his team will have a better understanding of the project soon. Animal studies will likely start this summer, with preliminary data coming probably before the end of the year. “We ought to be able to get it and know by the end of the year whether it can be done,” he says. “Right now, no one knows.”
Fewer fractions, more competitive
The physical properties of proton therapy — it deposits a dose in a precise volume, and can spare more healthy surrounding tissue from radiation — means using it in the treatment of rare pediatric brain cancers is relatively uncontroversial. But the growth in treatments for prostate cancer, for which Medicare can pay $50,000 a treatment, has drawn criticism, mostly because of the lack of studies showing it leads to better outcomes than other, cheaper forms of radiation therapy.
But Slater says that as proton therapy advances and providers become more experienced, the modality can become more competitive. And it can do this by reducing the number of fractions — or visits — required to treat a patient.
“When protons get up to par, to where they should be, we won’t have these long weeks of treatment,” he says.
When he began in the early days, Slater says fractions were similar to X-rays, around eight weeks long. But now his group is working on reducing that protocol to four or five weeks.
“Some of them have been cut roughly in half, but it’s going to go less than that. The small (tumors) will probably be just like we’re doing on the brain, one day, one treatment,” Slater says. “Most of the people who go into protons know that this will be a thing of the future and admit they need to get that (fractions) down,” he adds.