New stereotactic treatment technologies represent significant progress toward turning cancer into a manageable condition.

Cutting-edge radiation oncology departments are pioneering ultraprecise stereotactic radiation treatment and bringing new hope of eradicating previously unreachable tumors. How? With a new breed of medical linear accelerator, specialized accessories, and techniques adapted from brain radiosurgery. This new dimension in radiation oncology makes it possible to think seriously about transforming cancer from a fatal disease into a manageable condition.

In October 2004, a 56-year-old woman became the first person treated with image-guided radiosurgery using Varian’s new Trilogy™ machine, an ultraprecise, high-powered linear accelerator with an On-Board Imager™ accessory. A 10-year survivor of lung cancer, the woman underwent radiosurgery for two small metastases in the brain. The single procedure delivered a cancer-killing radiation beam so powerful and tightly focused that it was called radiosurgery instead of radiation therapy. The patient was back at work within two days.

Had she been treated a month earlier, this patient would have received low-dose radiation to her entire brain, with less probability of eradicating the cancer. “Given her favorable long-term outlook, we were committed to delivering a focal high-dose radiation treatment to eliminate the risk of brain injury from radiation treatment to the whole brain,” explains Ian Crocker, MD, professor of radiation oncology at the Emory University School of Medicine in Atlanta, Georgia.

The case at Emory is just one of many examples of stereotactic treatments that take advantage of recent advances in imaging, precision beam delivery, treatment planning, and automated patient-positioning technologies.

In standard forms of external beam radiation therapy, the patient receives the radiation dose in small daily increments over a period of weeks. By contrast, stereotactic radiation treatment delivers very high radiation doses in a short course of only a few days—or even a single session. Recent studies have suggested this strategy can be more effective at killing or controlling certain types of cancer.

Delivering higher radiation doses safely, however, requires a higher standard of precision in targeting the beam to the tumor shape and exact location. Varian’s Trilogy machine is the first medical linear accelerator optimized for stereotactic treatments. It has a more tightly focused beam and can deliver doses more than 60 percent faster than conventional accelerators to reduce the effects of tumor motion, shorten treatment times, and enhance patient comfort. It can be equipped with a highly maneuverable On-Board Imager accessory with radiographic, fluoroscopic, and cone-beam CT scanning capability for image-guided patient positioning.

The precision of stereotactic radiotherapy promises exciting new options for patients, enabling radiation treatment at earlier stages when cancer is most curable, making many inoperable tumors treatable, and providing a noninvasive alternative to surgery.

ADVANCED TREATMENT FOR MORE PATIENTS
A young mother is one of 90,000 people worldwide who develop spinal tumors each year. In her case, the location of the tumor near the spinal cord makes surgery and standard external beam radiation treatment too dangerous.

The University of Texas M.D. Anderson Cancer Center in Houston is one of the few treatment centers where doctors offer stereotactic spine radiotherapy using a modified linear accelerator. A CT scanner in the treatment room is used to scan the patients and ensure they are positioned precisely for treatment. “Almost every type of cancer can spread to the spine, so there is a great clinical need for the procedure,” explains Eric Chang, MD, director of the Stereotactic Spine Radiotherapy Program. “However, it isn’t widely available because it is so complicated to perform.”

Varian’s Trilogy accelerator, which combines treatment delivery and imaging in a single system, represents a significant step toward making this kind of treatment easier to deliver. “With the CT imaging that is available on Trilogy, we hope to cut treatment time from the two hours it takes today to 30 minutes,” says Chang. “This advance may make stereotactic spinal radiotherapy available in more centers.”

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