Researchers are testing a new procedure that may kill lung cancer tumors without debilitating side effects.
Stereotactic body radiotherapy is being tested at the Indiana University School of Medicine on patients with early-stage lung cancer. The technique combines a unique radiation treatment with 3-D imaging and a new body frame.
"The reality is when patients are treated with radiation currently, in the majority of patients tumors will not be controlled by current doses of radiation," said Dr. Robert Timmerman, assistant professor of radiation oncology at Indiana University and a lead investigator in the trial. "A large percent of tumors come back despite the treatment."
Timmerman said the new therapy should enable surgeons to increase the dose of radiation while decreasing toxicity because stereotactic radiation causes less damage to surrounding healthy tissue.
"When you have side effects, they come from the innocent surrounding normal tissue being incidentally treated, not from giving a high dose to tumors," Timmerman said.
The technique uses intensity-modulated radiation technology (IMRT), which delivers radiation to a tumor with varying intensity according to its shape and size. A 3-D, computer-generated grid system maps precisely the spot where the therapy needs to go, then the patient receives multiple "shots" of photon beams from a linear accelerator.
The key to the procedure is the unique body frame that holds the patient still, which researchers say will allow them to target the tumor more accurately than ever. It can deliver higher dosages because it will allow less so-called radiation "fallout" into healthy tissue.
"IMRT is a great technology and a lot of people don't know about it right now," said Jonathan Borden, assistant professor of neurosurgery at Tufts University. "This may be one of the things that will cause people to use more IMRT."
Using the new procedure, scientists hope to achieve the accuracy of gamma knife radiosurgery, an extremely precise, non-invasive technique used successfully on brain tumors.
"[All] of the stereotactic techniques are trying to achieve a very high dose in the target and low dose outside the target," said Borden, who often performs brain operations.
To perform gamma knife radiosurgery, the brain is immobilized by clamping a frame to the skull, allowing little or no motion from the patient.
"But in the body, the heart has to beat, you have to breathe, your bowels are going to turn -- it's difficult to stop these inherent motions," Timmerman said. "While you breathe the tumor is often moving up and down."
So Timmerman's group is testing a unique body frame designed by Swiss researchers to keep the body as motionless as possible.
Patients must sit still for about an hour for the treatment, while the linear accelerator beams radiation for about 20 minutes at a time. Each person will receive three outpatient treatments over a period of a week-and-a-half. The first patients began treatments on February 1.
To qualify for the trial, patients must have early-stage lung cancer and be unable to undergo surgery. Often, lung cancer patients are smokers and also have as emphysema, heart disease, or diabetes, which put them in too delicate a state for many lung cancer treatments.
Early-stage lung cancer usually is treated with surgery, conventional radiation, or the two together. Surgery alone gives a 60 to 70 percent cure rate for early-stage lung cancer, and traditional radiation, which involves five to six weeks of daily radiation treatments, gives a 20 to 30 percent cure rate.
"There's a lot of room for improvement here," Timmerman said.
