• 7/17/2006
  • Houston, TX
  • Juan A. Lozano
  • Chron.com

Knees bent and hands above his head, Francis Maloy lay on his back on a narrow, metallic table inside a white chamber, waiting for a giant wheel-like device to bombard the tumor in his chest with protons.

“I had never heard of proton therapy. The last time I heard about protons I was in college taking physics,” said Maloy, a 68-year-old retired Army colonel from Stuart, Fla., just before the procedure.

Maloy, who has advanced lung cancer, is one of the first patients being treated at the University of Texas M.D. Anderson Cancer Center’s new $125 million Proton Therapy Center.

It is the largest of the nation’s four such facilities that treat cancer by targeting protons narrowly on the tumor itself, sparing the healthy tissue that with traditional X-ray radiation therapy is blasted along with the cancer cells.

From inside one of five treatment rooms in the 94,000 square-foot center, the gantry looks like the airlock of a science-fiction spaceship. But behind it sits the bending magnets, electrical wires and monitors that make up the gantry, encased in a steel barrel, three stories tall and weighing 190 tons.

The protons, which are stripped from the nucleus of hydrogen atoms in a tubular device called an injector, are sent to a compact particle accelerator — actually a ring of magnets about 20 feet in diameter — called a synchrotron. There they circle around until they gather enough energy to irradiate a tumor before being sent toward the patient.

Dr. James Cox, chief of radiation oncology at M.D. Anderson, wasn’t always a believer in the technology.

“Studies have showed proton therapy allows an increased dose to a tumor but you have a decreased dose to healthy tissue and have fewer side effects” such as loss of appetite, diarrhea and headache, he said. “That was the breakthrough, what changed my mind.”

Cox said proton therapy can be used to treat cancers of the prostate, eye, lung, brain, head and neck and possibly tumors in the liver. It also helps treat cancer in children, who are more sensitive than adults to the side effects of radiation therapy.

But Cox said proton therapy, which is covered by Medicare and most insurance companies, is about three times more expensive than traditional radiation, in part because of the cost of the facilities.

Some doctors worry that the benefits to a few cancers don’t outweigh the enormous costs, especially when recent advances in traditional radiation make it safer to use.

Dr. Eric Horwitz, clinical director of the Department of Radiation Oncology at Fox Chase Cancer Center in Philadelphia, said proton therapy has an advantage in treating relatively rare cancers such as those in children or of the spinal cord.

More study needs to be done to see whether proton therapy is more effective for common cancers, such as prostate and lung, than newer forms of traditional radiation therapy that can also be focused on a tumor, he said.

Reducing radiation’s side effects could translate into lower health care costs in the long run, said Dr. Nancy Mendenhall, chair of the Department of Radiation Oncology at the University of Florida’s College of Medicine.

“I think it will be a part of mainstream radiation oncology if we fully embrace its advantages,” said Mendenhall, who is also medical director of the Florida Proton Therapy Institute, a new center set to open this summer in Jacksonville, Fla. “Conventional radiation therapy will always be a part of cancer treatment.”

A study that appeared last September in the Journal of the American Medical Association concluded that men who were treated for prostate cancer with higher doses of radiation, in part through proton therapy, were less likely to have cancer return than men who got traditional X-ray radiation treatment.

An accompanying editorial to the study by Drs. Theodore DeWeese and Danny Song with Johns Hopkins University School of Medicine in Baltimore questioned whether higher doses of radiation are the best way to improve outcomes.

“As such, this study has not answered the important question of whether patients should accept the modest but real incremental risk of higher radiation doses for the uncertain ultimate benefit derived,” DeWeese and Song wrote.

Maloy will get proton therapy five days a week for about two months. He also gets chemotherapy once a week.

Each treatment session takes 30 to 45 minutes, much of that time spent taking X-rays of Maloy’s tumor and positioning the gantry’s protruding snout that the protons shoot out of.

The procedure is just like an old-fashioned X-ray: Just before the protons started flowing, an alarm went off, warning everyone to leave the room. After a few minutes the treatment stopped and nurses and doctors repositioned the snout to hit the tumor from a different angle.

“I feel nothing in there, except it’s uncomfortable laying on their machine,” Maloy said. “You don’t know anything is happening. It’s magical.”

Proton therapy has been around since the mid-1950s but was done mostly at research facilities, according to the National Association for Proton Therapy.

Loma Linda University Medical Center in California opened the world’s first hospital-based treatment facility in 1990, and Indiana University and Massachusetts General Hospital in Boston also have such centers. But M.D. Anderson’s is the largest.