A Powerful Weapon Against Difficult Cancer: CyberKnife Tracks Moving Target With Robotics and Focused Beams

First, a doctor told Marsha Badagliacca that she was going to die. It was the least likely thing Badagliacca expected to hear. She was 61 and had never smoked. Now, she had cancerous tumors in both lungs. And they were at Stage IV, the most advanced in extent or distribution, that doctor said. Hearing a physician deny her any future “was the most devastating medical experience,” Badagliacca said.

Marsha and Larry Badagliacca Marsha Badagliacca and her husband, Larry, have grandchildren now and health has never been so important.

Amidst this discouraging news, Badagliacca discovered she did have options. She found a different doctor and began a series of treatments with the most advanced chemotherapy drugs available. “I made a decision that fear was not going to be part of my program and that I would do all I could,” she said. “I joked with one of my doctors that if they kept inventing things for me to take,” she said, “I would stay alive to take them.”

For five years, one new chemotherapy drug after another kept Badagliacca going. Yet the tumors always came back. Then, the multidisciplinary tumor board at the Stanford Cancer Center agreed to review Badagliacca’s case. What they found made her a perfect candidate for something new – not a drug, but a new form of delivery for a long-time weapon against cancer. In 1999, after years of work, a Stanford Hospital & Clinics physician, John Adler, MD, won FDA approval to treat patients with brain cancer with his invention, the CyberKnife. By 2001, the FDA approved its use anywhere in the body. With the look of an overblown toy, the CyberKnife is no knife at all, except in effect. Its tool is radiation, one of the basics of cancer treatment since the 1920’s. The CyberKnife’s special power is how it puts the radiation into the body.

Radiation Without Spillover

Treating cancer has long been a carefully negotiated balance between good and bad. Badagliacca’s tumors were re-evaluated at Stanford, not as Stage IV, but as an early stage of an unusual, slow-growing lung cancer that often appears in non-smokers, especially women. Surgery was not possible because it would have left Badagliacca with too little breathing capacity. Radiation was her next best hope.

Marsha Badagliacca The odds against Marsha Badagliacca were difficult when she was diagnosed with lung cancer six years ago. With new treatments, her future has changed dramatically.

While radiation is good to destroy cancer cells, it kills healthy cells, too. Adler’s quest, then, was to build a delivery system that could get a lethal dose of radiation to the cancer without spillover and to get the radiation to wherever the tumor was at any given moment, regardless of body movement.

The CyberKnife, Badagliacca said, “gave me a whole new option for fighting the cancer and surviving it.”

More than 400,000 Americans live with lung cancer, with another 200,000 newly diagnosed each year. More than 160,000 people die each year from the disease. Ninety percent of new lung cancer cases are attributable to smoking. Non-smokers like Badagliacca, who grew up in homes where people smoked, are at 20 to 30 percent increased risk to develop the disease. Unfortunately, the survival rate for lung cancer is lower than most other cancers, driven in large part by its lack of symptoms until the disease reaches its later stages. Only 16 percent of lung cancer tumors are found while still localized. About one in six people with the disease die within one year of diagnosis.

“I joked with one of my doctors that if they kept inventing things, I would stay alive to  take them.”
– Marsha Badagliacca, lung cancer patient

Those numbers drive the work of physicians such as Billy Loo, MD, PhD, Badagliacca’s physician at Stanford and leader of the Hospital’s Thoracic Radiation Oncology Program. Stanford has been at the forefront of developments in radiosurgery―radiation focused with surgical precision, combined with advances in imaging systems to see cancer and track the radiation delivery.

Mapping A Moving Target

The CyberKnife, Loo said, is a leading edge radiosurgery player to treat difficult cancers such as Badagliacca’s. Its methodology, which Adler first prototyped in 1994, delivers radiation in highly focused beams that keep the radiation away from healthy tissue. Keeping the radiation under tight control allows physicians to deliver a higher dose of radiation with each treatment. That translates into fewer treatments, which translates into a patient being able to tolerate almost double the total amount of radiation in conventional treatments. The increased intensity of individual doses in the CyberKnife increases the DNA damage done to the cancer cells, which increases the odds they will not be able to reproduce and grow.

The CyberKnife’s movements achieve their precision through sophisticated robotic engineering, but knowing where to go is the first step. “The key to radiosurgery is seeing the tumor, focusing the radiation on the target and verifying that we are hitting that target,” Loo said. Stanford physicians can build a four dimensional image of a patient by integrating information from a CT scan’s view of the body’s anatomy with the PET scan’s view of that anatomy’s biochemical behavior. The final image is a map of a tumor in time and space, a crucial guide for treatment.

Constant Adjustments

Billy W. Loo Stanford Hospital & Clinics physician, Billy W. Loo, MD, PhD, became interested early in his education about how to combine several elements of technology and medicine together for more effective cancer treatments. Surrounding him here, the CyberKnife system.

Using that imaging as a guide, the CyberKnife moves around the body, moving its beam in minute increments to literally breathe along with the patient, driven by information from an imaging system that continuously calculates the tumor’s position, following it as it moves with each 12 to 20 breaths a minute. Its robotic arm moves its compact linear accelerator to aim beams from hundreds of directions around the patient.

The treatments can take a couple of hours, with the patient held in position by a soft form molded to the body. The treatment protocol includes music, whatever type a patient prefers. Badagliacca also has a relaxation routine that helps her maintain the steady breathing pattern that aids the treatment. “There’s no pain,” she said. “But I was a bit sore for a couple of weeks afterward, if I took a deep breath. But it was nothing to complain about.”

“My stock and trade phrase is now, ‘If I didn’t know I had cancer, I wouldn’t know I was ill.’ ”
– Marsha Badagliacca, lung cancer patient

While a growing number of hospitals are adding radiosurgery techniques, Stanford remains the only facility to have the combination of two CyberKnife systems, a 4D PET-CT scanner dedicated to radiation planning and a Trilogy, another radiosurgery system. Loo added it to Badagliacca’s treatment because it could treat the two tumors in her right lung as they moved in different directions and capture CT scans to verify accurate positioning.

CyberKnife Quick Facts:

  • The CyberKnife is able to follow a moving tumor with its beam of radiation, effectively breathing along with the patient, because of a computer process that combines visual information about the patient to continuously calculate where the tumors are. The imaging system also sends visual information to verify that the radiation has been accurately delivered.
  • The CyberKnife’s ability to deliver high-speed, finely honed beams of radiation depends on a medical linear accelerator, now the crucial backbone of many other life-saving medical devices.
  • The first such accelerator in the Western Hemisphere, debuted in 1956, was designed and built by Stanford Hospital radiation oncologist Henry Kaplan and Stanford University physicist and engineer Edward Ginzton.
  • That first accelerator is now in the permanent collection of the Smithsonian Institution in Washington, D.C.
  • Stanford neurosurgeon John Adler, the inventor of the CyberKnife, first began to think about making a machine that would be flexible and guided by advanced imaging in 1985.
  • The first prototype was ready to treat patients in clinical studies in 1994.
  • Stanford Hospital has treated over 2,500 patients using the Cyberknife system.

Collaborative power

But, Loo said, “At least as important as our advanced technology are the brains behind it. One of the breakthroughs in this case was the insight gained through the collaboration of physician specialists in lung cancer, including radiation oncologists, medical oncologists, thoracic surgeons, pulmonologists, radiologists, and pathologists.” As a facility with the longest experience with the CyberKnife, Stanford’s radiosurgery treatment team has been built to include specialist physicians, physicists, dosimetrists, therapists, and nurses. “Our active collaboration is what distinguishes us,” Loo said. “We are constantly striving to learn more.”

CyberKnife apertures

Each patient’s treatment is unique, and the CyberKnife’s selection of apertures adjust the size of the beams of radiation sent against cancerous tissue.

The Hospital’s CyberKnife use includes treatments for several types of cancer:―brain, liver, pancreas, prostate and nasopharynx; research and clinical trials are also underway to further advance treatment protocols.

Badagliacca has resumed her life with gusto. “My stock and trade phrase now is, ‘If I didn’t know I had cancer, I wouldn’t know I was ill,’ ” she said. “I feel very blessed to have been eligible to have this procedure done.”

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