A radiation therapy system that improves doctors' ability to treat the tumor, the whole tumor, and nothing but the tumor is revolutionizing the treatment of certain cancers at Dana-Farber Cancer Institute and Brigham and Women's Hospital (BWH).
These partnering institutions use Novalis TxTM stereotactic body radiosurgery systems, which combine advanced radiation delivery equipment with imaging technology for mapping the precise dimensions and location of a tumor within the body.
The systems, housed in suites at both Dana-Farber and BWH, are currently being used to treat patients with some types of small, early-stage lung tumors that cannot safely be removed by surgery. In the past, these people had few effective options available.
"It's very rare for a technological innovation to radically improve cancer survival rates," says David Sher, MD, MPH, of Radiation Oncology, a joint department of Dana-Farber, BWH, and Boston Children's Hospital.
"We can give 10 times the dose of radiation used in earlier systems and improve tumor control rates by 50 to 60 percent, usually with few complications."
Stereotactic radiosurgery is a technique pioneered at BWH that uses angled beams of radiation to produce a radiated field closely conforming to the tumors' size and shape.
It has been refined over the past 10 years in patients with inoperable brain tumors, for whom it can provide an enormous benefit, says Department of Radiation Oncology Chair Jay Harris, MD.
"It has given us the ability to treat tumors in the brain with large amounts of radiation, but, because the radiation is so closely focused on the tumor, normal tissue is spared and patients experience few cognitive or functional problems," he says.
Such problems were common with earlier forms of radiotherapy, which produced more damage to healthy tissue.
Doctors expect to achieve similarly impressive results in lung tumors. "The technology allows us to sculpt the beams of radiation around precise contours," Sher says.
Lung cancers have long posed a challenge to radiation therapy because the rise and fall of the abdomen and lungs during breathing makes the tumors difficult to target — a problem not associated with brain tumors, where the head can be immobilized during treatment.
With the new system, doctors can implant tiny metal "seeds" in the tumor, enabling the machinery to follow its movement and deliver radiation when the tumor is in the precise position necessary.
"By tracking the motion of the tumor during the patient's breathing cycle, smaller radiation fields and potentially larger doses can be used, improving rates of tumor control and reducing side effects and complications," says Aileen Chen, MD, MPP, of Radiation Oncology.
The machine also includes a flat panel detector, similar to a digital camera, which captures radiation that passes through the tumor but doesn't interact with it.
Images created from this "leftover" radiation show the location of the target as it is being treated and confirm the accuracy of the treatment.
"This technology continuously displays what is being treated, offering additional safety for patients and peace of mind for our physicians," say physicist Ross Berbeco, PhD, who developed the new approach with colleagues in Radiation Oncology.
"The enhanced radiation delivery capabilities of these state-of-the-art machines go hand-in-hand with recent advances in functional imaging that better delineate where the tumor is and how aggressive its biology has become in individual patients," says Mike Makrigiorgos, PhD, director of the Division of Medical Physics and Biophysics.
"Clearly, a highly personalized radiation treatment is gradually becoming a reality using advanced new technology."
As the technology proves itself in lung cancer patients, physician researchers at Dana-Farber and BWH are planning clinical trials of its effectiveness in treating other small solid tumors, including those in the pancreas, prostate, and liver.