Experts Debate CyberKnife for Prostate Cancer

The CyberKnife enables men to complete treatment in just four or five sessions by much more accurately delivering about quadruple the usual dose of radiation each time. Doctors inject four tiny gold cylinders into the prostate to create a precise target. The patient lies on his back for each one-hour session as a robotic arm swivels around to shoot dozens of beams from multiple angles.

"You are able to give very high doses and sculpt those doses to the tumor," said Omar Dawood of Accuray Inc. in Sunnyvale, Calif., which has installed more than 90 systems in the United States as doctors have started using the machine for other cancers. "It could revolutionize the way prostate cancer is treated."

Dawood said that more than 2,000 prostate cancer patients have been treated, and that the approach seems to work as well as standard treatment with about the same, or perhaps even fewer, short-term side effects. At least one study that followed patients for several years indicates that it continues to be safe and effective, and the company is sponsoring two new studies at multiple sites nationwide.

"We've been getting very good outcomes," said Georgetown's Collins. "Prostate cancer is a real killer, and people are not getting treated because it's inconvenient for them. This offers them a much more convenient option."

At the Virginia Hospital Center, the CyberKnife is quickly becoming the most popular option.

"About half of our patients are CyberKnife now," said Timothy Jamieson, medical director of radiation oncology.

Robert Blythe, 56, of Sterling was treated with the CyberKnife at Virginia Hospital Center this summer after his early prostate cancer was diagnosed.

"It sounded great to me," said Blythe, who did not want to face two months of driving more than an hour each way from the auto body shop he runs in Winchester to be treated. "Being new and on the cutting edge, it seemed like the right thing to do. This would be much more convenient."

While there is a biological reason to think that fewer high doses of radiation may work well for prostate cancer, skeptics said the studies done so far have been too small and followed patients for too short a time.

"We just don't have the data to support treating prostate cancer with five days of radiation," said Kevin A. Camphausen of the National Cancer Institute, noting that prostate cancer can recur many years or even decades later. And high-intensity radiation, even though it is more precisely focused, might still damage the rectum, bladder and urethra, potentially causing complications years later.

"What I'm worried about is that we might not be curing patients who we know are curable," he said.

Although several systems can perform similar procedures, CyberKnife has been promoted most aggressively. In the Washington area, Georgetown has bought radio ads and Metro signs and sent direct mailings to doctors, while Virginia Hospital Center has been running ads in local newspapers and mailing brochures to nearby homes. In other areas, billboards prominently tout the treatment.