Neutrons against cancer

25 years of neutron therapy at Fermilab

The idea to build a medical facility at Fermilab developed in the early 1970s when physicians and physicists shared a vision: to wield accelerator technology to combat cancer. Today, more than 3,100 patients have come to Fermilab in the hope of finding a cure for some of the worst tumors known in the medical field.

Former patient Rahel Kent, who came to NTF in 1996, shared her story with the audience, recalling how it all started.

"First it felt like a sore throat," she said. "Weeks later, half my throat was blocked."

Physicians didn't immediately recognize the growing tumor. Soon, however, Kent learned the shocking truth. At age 34, she had developed salivary gland cancer, a rare disease usually associated with older people who chew tobacco, a habit she had never practiced.

She was offered a devastating solution to the problem: Surgery that would remove large parts of her jawbone, two-thirds of her tongue and hopefully the entire tumor. It was unclear whether Kent would be able to keep her voiceó or even stay alive.

"My articulation is the essence of what I do," said Kent, who works as a criminal defense attorney in Los Angeles.

She decided to look for treatment alternatives and used the Internet to find more information. After a few unsuccessful searches, she finally made the right decision.

"I typed the words salivary gland cancer," she said. "I had eighteen hits, nine from Fermilab."

She called Arlene Lennox, the head of Neutron Therapy Facility at Fermilab. Learning the details of Kent's disease, Lennox asked her to send copies of her medical records to Dr. Jeffrey Shafer of Provena Saint Joseph Hospital, which operates NTF. Soon Kent received a phone call from Shafer, and she talked to him for three hours. Eventually she received an appointment for neutron treatment - and she was cured.

"Dr. Shafer is not only one of the finest physicians, but also one of the finest human beings I know," Kent enthusiastically described her encounters with the physician. "He has a heart of gold."

Shafer is one of several physicians who treat patients at NTF and continue to build upon a quarter century of beams for healing. On September 7, 1976, Frank Hendrickson and Lionel Cohen were the first physicians to treat a patient at NTF.

"Hendrickson took a leadership role," said Lennox. "He had to address three constraints. First, neutron treatment could not interfere with the high-energy physics program. Second, he had to get his own money. And finally, the doctors had to head the [medical] research and make the final decisions."

Hendrickson initially worked with Fermilab physicists Cy Curtis and Don Young, who were very supportive of the idea to use a fraction of the high-energy proton beam for medical purposes. After it became clear that the Linac could accelerate and deliver more protons than needed for the Main Ring accelerator, the Universities Research Association, which operates Fermilab, provided 75,000 dollars of seed money and encouraged Hendrickson to obtain more money from charities and other funding organizations.

With the help of Fermilab physicists, Hendrickson soon devised plans for a new medical facility.

"In our first proposal, we wanted to do everything: protons, neutrons, pions," recalled Hendrickson. "But it was considered much too big by the National Cancer Institute. We then submitted a scaled-down project with just neutrons."

The neutron proposal didn't require the construction of a new building that would have cost more than a million dollars. Instead, it relied on the conversion of a freight elevator, which technicians had used to lower equipment into the accelerator tunnel, into a treatment room in which patients could be lowered into a new neutron beamline to be built. The National Cancer Institute approved the plan and provided funding.

To create the neutron beam, Young and his colleagues designed and constructed two magnets to divert a fraction of the Linac proton beam, bend it around a ninety-degree curve and direct it toward a beryllium target outside of the freight elevator. The 66-MeV protons interact with the beryllium atoms and produce fast neutrons that travel in the same direction as the original protons, eventually entering the treatment room through a collimator, a concrete cylinder with a hole at its center.

Positioning a patient in front of the hole and choosing a collimator with the right hole size, NTF specialists can deliver neutrons to a tumor of any size while minimizing the exposure of healthy cells to the beam. Because the neutrons damage cancerous cells much more than any other form of irradiation, NTF patients only need to receive one third of the number of treatments compared to patients of photon or proton treatment centers.

To explain the differences in the various therapies, Hendrickson compared photon (x-ray) and neutron beams of equal energy.

"The effect of photons is like one thousand ping pong balls entering a room and bouncing around," he said. "Now put the same amount of energy into one bowling ball. That's the neutrons. If they strike a part of the DNA, it cannot be repaired by the cells. The damage done by photons can often be repaired."

Because of cost, photon treatment is still the preferred form if doctors decide to use irradiation. For tumors located near critical nerves like the spinal cord or inside an eye, proton treatment has proven to be very effective. The Loma Linda University Medical Center, for which Fermilab built a proton accelerator in the late 80s, treats about one thousand patients a year, one third of all proton patients in the U.S. But for some types of cancer, referred to as radioresistant tumors, both photon and proton therapies fail. Only the more powerful neutron treatment provides the chance of eliminating these tumors that are often inoperable and too large for chemotherapy.

"The first NTF doctors went after those patients that had no other options," said Lennox, who has worked at NTF since 1985. "Photon treatment applies to about seventy percent of all cancer cases treatable with radiation. In fifteen percent of cases, tumors are small and close to critical structures, and proton beams are the most effective. The final fifteen percent present hard to treat cases of cancer. That's where neutrons are the treatment of choice."

To honor the work of the early pioneers, Lennox, who received an award from Fermilab director Mike Witherell for her "vision, commitment and compassion," presented on behalf of NTF an award to Frank Hendrickson, who retired from NTF in 1995, as well as a posthumous award to Lionel Cohen, who died in 1999.

"Hendrickson and Cohen took the medical program from research to an accepted choice of treatment that Medicare and health management organizations would pay for," Lennox said.

Lennox also presented a posthumous award to medical physicist Miguel Awschalom, who had greatly contributed to the development of NTF during its first ten years, and she announced that the Honorable J. Dennis Hastert, Speaker of the U.S. House of Representatives, would receive an award for "his support of the Neutron Therapy Facility." Hastert, who had to cancel his ceremony participation on short notice, has helped NTF to upgrade its facilities with a computerized tomography scanner and secured funding for additional improvements.

The NTF now has the only vertical CT scanner in the U.S. "We now can do CT scans of people sitting or standing, in exactly the position in which they will receive neutron treatment," Lennox said, explaining the significance of the new instrument.

Accelerators, however, remain one of the most important tools in the battle against cancer. Former patients like Kent are proof for the successful partnership of physics and medicine.

"Fermilab saved my life," she said.

by Kurt Riesselmann

On the Web:

Streaming video: Neutron therapy retrospective http://vmsstreamer1.fnal.gov/VMS_Site_02/VMS/NTF/index.htm