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Spacecoast Living

CyberKnife

treats tumors with precision,
and now it’s at cancer care centers

By Anne Straub

After a prostate screening showed elevated levels of a cancer indicator in his blood, Scott Silver remained confident that further tests would show he was healthy. When his doctor recommended a biopsy, Silver was sure it would be negative.

And so the Naples resident was devastated when results showed he had prostate cancer.

Silver, a retired orthopedic surgeon, was well aware of potential complications from surgery and the serious side effects of other treatments. When a friend passed along a brochure describing a new treatment available in his area, Silver thought he might have his answer. After further research, he decided to undergo treatment with CyberKnife, a radiation system that uses robotics to achieve an unprecedented level of accuracy in treating tumors.

The elevated prostate screening was in January last year, and he had the CyberKnife treatment the following May. The amount of prostate-specific antigen in his blood plummeted, and he experienced no side effects.

“I’m just thrilled with the results,” said Silver, 62. “I feel I’m cured,” he said, although he concedes it’s too early to know for sure.

Doctors and staff at the Cancer Care Centers of Brevard hope to generate more stories like Silver’s. The Melbourne facility has installed the CyberKnife system and expected to begin treating patients in April.

“We are very excited,” said Dr. Silas Charles, a radiation oncologist and director of the center. “We always try to do innovative things for the community,” he said, calling the CyberKnife the latest weapon in the fight against tumors.

Despite the name, the CyberKnife performs no cutting. Instead, CyberKnife delivers hundreds of beams of focused radiation through a robotic arm that continuously adjusts for tumor and patient movement throughout the treatment.

The tool is a product of Accuray Inc., a California company that trades over the counter under the symbol ARAY. The company estimates more than 20,000 patients have been treated with the tool worldwide.

The Melbourne system is the sixth CyberKnife site to open in Florida. The new treatment option represents a more than $4 million investment by the Cancer Care Centers. The equipment offers a precision that Charles hasn’t seen in any other system. Technicians calibrating the machine before it goes into service can’t believe its accuracy, he said.

That precision allows CyberKnife to treat tumors that previously might have been untreatable by radiation because of the danger of harming nearby organs. CyberKnife represents significant improvement over traditional radiology systems in a couple major areas, Charles said.

Previous systems used beams from a device that pivoted on a single point, which offered limited angles for attacking a tumor. CyberKnife’s robotic arm introduces a new flexibility, allowing doctors to map a session using hundreds of beams of radiation from all angles. Accuracy is measured at the sub-millimeter level.

The tool also is able to compensate for patient movement by using an image-guidance system that tracks the tumor. The technology keeps the radiation trained on the target, even while the patient is breathing, without the use of frames to immobilize the patient. Other radiation systems register a target only at the beginning of a treatment session and cannot compensate for patient movement; patients  might have to hold their breath at times to avoid moving and having the radiation miss its target.

CyberKnife’s increased accuracy means that doctors are able to deliver a higher dose of radiation to the tumor, because of the lessened risk of damaging nearby organs. That means shorter treatment for the patient: A conventional radiation therapy treatment of 20 to 30 sessions over six to eight weeks, at a low dose of radiation, could be done in five sessions or less – a week or under -- with the CyberKnife.

A potential downside could be the longer length of each of those treatments. Where previous sessions lasted half an hour, patients may lie on the table for CyberKnife treatment for one or two hours. Sedation might be an option to increase comfort for the patient, Charles said.

CyberKnife can treat benign and malignant tumors in the head, neck, lung, pancreas,  prostate or pelvic organs, spine, kidneys and liver, as well as melanoma, recurrent diseases and previously treated areas. In some cases, it can be used to reduce an inoperable tumor to a size that can be surgically removed.

The tool isn’t recommended for all tumors. For example, breast cancer patients likely would undergo more generalized radiation to treat the entire breast, Charles said.

If a patient is recommended to undergo the CyberKnife, treatment starts with about a week of diagnostic tests. The data is used to pinpoint the tumor and map a radiation delivery plan. Gold markers, about the size of grains of rice, are implanted in the tumor to help guide the radiation toward the target. The patient lies on a table during the session, while the robotic arm moves around to deliver radiation.

Investing in the equipment and additional staff is a gamble, Charles said, but he calls it a “faith gamble,” a sort of karmic sure thing. “If it’s good for the patient, things happen,” Charles said.