INOPERABLE LUNG CANCER IN THE CROSSHAIRS
Surgery can be an effective treatment for early-stage non–small cell lung cancer, which strikes more than a million people worldwide each year. But surgery is out of the question for a dearly loved grandfather because he also has advanced emphysema.

Stereotactic radiotherapy can be an alternative for cancer patients like this man, who have other ailments that preclude surgery. The standard radiation treatment for inoperable lung tumors takes 30 daily sessions. Researchers at the Indiana University School of Medicine theorized that a higher dose delivered over just three sessions might be more effective and less dangerous for frail patients.

According to Robert D. Timmerman, MD, formerly of Indiana University and now at University of Texas Southwestern in Dallas, the Indiana clinical team was able to safely escalate the dose to levels they thought would improve on tumor control rates. Without the benefit of a Trilogy machine or an On-Board Imager device, they managed by immobilizing patients in a stereotactic body frame and using a conventional linear accelerator. A machine like Trilogy, with its On-Board Imager device, would have been extremely helpful, Timmerman says.

“An On-Board Imager accessory allows you to see, on the fly, what you’re aiming at,” he says. “We try hard to be accurate, but there is always uncertainty that the target is where you think it is. On-board imaging adds to your confidence that you are aiming correctly, so you can limit the safety margins. It might allow treatment of a smaller volume.”

Early evidence from Indiana points toward good local tumor control with few side effects. Now a group study based on this work is taking place in the United States at dozens of hospitals and clinics. Timmerman, principal investigator for the study, expects stereotactic radiotherapy techniques to advance quickly with the number of multi-institutional studies under way, including one in Germany on liver metastases and another in Japan on lung tumors.

The Kyoto University Graduate School of Medicine is one of 16 leading institutes in Japan participating in a three-year study involving 165 lung cancer patients. “If this study demonstrates that stereotactic radiation treatment can be a standard of care for inoperable non–small cell lung cancer, it will be good news,” says Yasushi Nagata, MD, PhD, Department of Therapeutic Radiology and Oncology. Because it is noninvasive, stereotactic radiation treatment could eventually become a preferred option for patients with operable tumors as well.

ZEROING IN ON MULTIPLE METASTASES
A woman with non–small cell lung cancer has several metastases in her liver. Three cycles of chemotherapy, the standard treatment, have had little effect.

Patients like this woman are not normally treated with radiation once their cancer spreads, but investigators at the University of Chicago in Illinois are trying something new. They are backing up chemotherapy with pinpoint stereotactic radiotherapy to small metastatic tumors in up to five sites anywhere in the body.

“By treating each small metastatic tumor with a very high dose over a few sessions, we hope to shrink or completely eradicate the tumors,” says Mary Martel, PhD, associate professor of radiation oncology.

With Trilogy, doctors may for the first time have a practical means of routinely treating tiny metastatic lesions where cancer has spread. Using new imaging processes such as PET/CT scans in post-treatment checkups, clinics may be able to detect these lesions and then eradicate them with image-guided stereotactic treatments. Thus, cancer could be turned into a chronic disease managed through a series of checkups and treatments when metastatic lesions reappear.

Varian introduced Trilogy at the beginning of 2004 and, by the end of September, had 27 orders for the new machine and several installations—a relatively fast adoption rate for a new technology in radiation oncology. The first Trilogy unit was installed at Emory University. “Using the Trilogy system, we have the potential to substantially improve cancer treatment outcomes,” says Lawrence Davis, MD, chairman of the Department of Radiation Oncology at Emory.

Visionaries see tremendous potential in the combination of new imaging capabilities and more precise tools for radiosurgery. “Imaging technologies are being developed that will eventually give us the same information for diagnosis and treatment that we get from surgical biopsy today,” predicts Emory’s Ian Crocker. “If we could make a diagnosis of lung cancer, for example, based on imaging information alone, we are certainly developing the tools to remove the tumors radiosurgically.”

In the meantime, the promise of stereotactic therapy is beginning to pick up speed.

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