Killing Cancer cells and Saving healthy cells

[RandyW]

New radiation therapies spare healthy cells

BY SUSAN JENKS

FLORIDA TODAY

Photographer Stephen Dalla Costa and his wife, Margaret, each have faced cancer -- requiring radiation therapy to help destroy potentially life-threatening tumors.

His wife underwent eight weeks of radiation last year to treat a lung cancer. But Dalla Costa said his radiation therapy to the prostate entailed just five treatments, allowing him to return home to Trinidad in the West Indies that much sooner -- and at far less personal expense.

Dalla Costa was treated at the Cancer Care Centers of Brevard in Melbourne with the "CyberKnife," a machine used against cancer, with an imposing robotic arm that rotates around the patient's body to deliver focused beams of radiation to a tumor from more than 200 angles at one time.

Like conventional radiation, the newer forms of radiation treatment, such as with the CyberKnife, require linear accelerators to deliver high-energy rays or particles to treat patients' disease.

But the newer devices also require highly trained physicians and other personnel, including trained medical physicists, to operate the sophisticated software needed to guide radiation safely across normal tissues, while hitting cancer cells' ability to rapidly divide.

Several similar machines perform radiosurgery, as this type of radiation therapy is called.

Radiation often is used to treat various cancers, either as an adjunctive or add-on therapy to surgery and chemotherapy -- or, as in the case of radiosurgery, to replace actual surgery, whenever possible.

Among the others radiosurgery devices is the "Trilogy," which is used by MIMA.

Dr. Todd Scarbrough, the medical director of MIMA's Melbourne Cancer Center, said his physician group opted to buy Varian's Trilogy, rather than Accuray's CyberKnife, to treat cancer patients, at a cost of about

$3 million, or $1 million less than its Accuray competitor.

"The CyberKnife is no better than the Trilogy," he said. "There is no diagnosis you can throw at it you can't treat" -- from "superficial skin cancers" to more complex tumors deep within the body.

Although Scarbrough said the Accuray machine "is good and it will do well," he described the Trilogy as far "more versatile," because it can treat larger tumors "from the size of a baby's fist to a football."

"And it's actually newer technology," first entering the market in 2005, he said.

Some experts say there is little data yet supporting claims that one of these powerful machines is superior to another.

$4 million investment

Still, the CyberKnife offers pinpoint accuracy at targeting tumors at the "sub-millimeter level," while sparing nearby healthy cells and allowing patients to go back to their daily activities quickly, said Dr. Silas Charles, a cancer physician and president of the Cancer Care Centers of Brevard.

Charles purchased the $4 million machine earlier this year -- and it is the only one in Brevard County.

"We are making the inoperable plausibly operable," he said, referring to the machine's ability to access and shrink complex and previously inaccessible tumors.

And for palliation -- when a cancer is beyond cure -- "we can relieve pain quickly, within 42 to 72 hours," he said, compared with a minimum of two to three weeks using traditional radiation therapy.

In addition, because the CyberKnife operates in "real time," Charles said, it corrects constantly to ensure the radiation beams stay on target, whether a patient accidentally moves, or an organ shifts slightly because of intestinal gas, for example.

"Other machines are not as real-time as this," he said. "The machine is checking all the time, and if anything is out of range, it shuts down immediately."

Patient experiences

Neal McCane, a 77-year-old Sebastian resident with prostate cancer, can attest to the CyberKnife's quick downtime, which he experienced during a recent radiation session of his own at the center.

"You can't move a whisker," he said, "or the machine will stop."

McCane said he has suffered no side effects from his short five-course radiation treatment, other than stiffness from lying still on a table for an hour or more each time.

And, like Dalla Costa, he will be tested within the month to see if his cancer is gone.

"This was a lot better than having 44 (radiation) treatments or undergoing surgery," he added, grinning. "I'm 77 years old, and I'll probably only live another 30 or 40 years."

"I feel tired occasionally, but that's about it," Dalla Costa said of his recent therapy. "There is no pain involved, although watching the machine coming over you can be a bit scary."

In describing the CyberKnife, Charles said tumor volume "is the limiting factor," so its best use comes with early diagnosis, when tumors tend to be small, and "you can have this (therapy) in the morning, and go play golf in the afternoon."

The machine's robotic arm, he said, enables it to "hit a tumor from multiple angles" almost anywhere in the body, without metal head frames or skull pins, once required to immobilize the head during radiation treatments.

"This is not a good treatment for larger tumors," Charles conceded, "but a small lung carcinoma, it can blow it away."

Initial results also suggest the CyberKnife works well against sarcomas, or bone cancers, which are traditionally radiation-resistant, he said.

Awaiting data

Dr. David Larson, a radiation oncologist at the University of California, San Francisco, takes a broad view of the technology.

The Trilogy and the CyberKnife are both good machines, he said, but no data exists to show one is actually better than the other, nor is there apt to be "a big clinical difference" in outcome, if patients choose their therapy from one over the other.

"In the absence of clinical data, this is subjective stuff," he said.

Although the university he works for owns a CyberKnife, Larson said, "that doesn't necessarily mean I like it. It has its pluses and minuses."

And like all technologies, Larson stressed, there are a number of socio-economic influences at play, including reimbursement rates set by Medicare and other insurers, which guide physicians' choices, as do noneconomic reasons, such as patient convenience.

Medicare and most insurers cover CyberKnife and Trilogy.

Scarbrough said individual doctors "have in mind what they are comfortable with, when they decide to upgrade" their cancer equipment.

"Some people look across the ocean and say 'I want a sailboat,' while others want a yacht," he said. "I want something that's efficient and works well."

Contact Jenks at 242-3657 or sjenks@floridatoday.com.

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