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Lab technician Sarah Bartlett, RTT, left, demonstrates the new technology.
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 and BWH.
In the past few weeks, these partnering institutions have put into service two NovalisTM Tx stereotactic body radiosurgery systems, which combine advanced radiation-delivery equipment with imaging technology for mapping tumors’ precise dimensions and location. The systems, housed in newly constructed suites at both Dana-Farber and BWH, are being used to treat patients with some types of small, early-stage lung tumors that cannot be removed safely 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,” said David Sher, MD, MPH, of Radiation Oncology, a joint department of DFCI, BWH and Children’s Hospital. “This system enables us to deliver very high doses of radiation per day, significantly improving survival in eligible lung cancer patients.”
Stereotactic radiosurgery—a technique pioneered at BWH that uses angled beams of radiation to produce a radiated field closely conforming to the tumors’ size and shape—has been refined over the past 10 years in patients with inoperable brain tumors, for whom it can provide an enormous benefit, said 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,” Harris said. Such problems were common with earlier forms of radiotherapy, which produced more “collateral 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 said. “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.”
Lung cancers long have 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 track 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,” said Aileen Chen, MD, MPP, of Radiation Oncology.
The machine also includes a flat-panel detector, similar to a digital camera, that captures radiation which 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 by radiation, offering additional safety for patients and peace of mind for our physicians,” said 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 delineate better where the tumor is and how aggressive its biology has become in individual patients,” said 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 DFCI and BWH are planning clinical trials to study its effectiveness in treating other small solid tumors, including those in the pancreas, prostate and liver.