Advances in radiation oncology now help doctors target malignancies more precisely.
Radiation therapy to treat cancer has always posed a challenge, because along with the power to kill malignant cells there’s the risk of damage to healthy cells nearby. As the field of radiation oncology has advanced, the delivery of radiation has become more precise, minimizing that risk. Fortunately, the last five years have brought dramatic progress in that regard.
“It’s a very exciting time,” says Alison Grann, M.D., chair of the Department of Radiation Oncology at Saint Barnabas Medical Center. One reason for her excitement is that the Medical Center is preparing to unveil its newest weapon: CyberKnife. That’s the brand name of a robotic radiosurgery system that delivers beams of high-dose radiation with extreme accuracy to hard-to-reach tumors anywhere in the body, including the prostate, lung, brain, spine, liver, pancreas and kidney. The system is expected to be operational at Saint Barnabas by December.
“Most radiation delivery systems can rotate 360 degrees in one plane around the patient,” Dr. Grann explains. “But this is on a robotic arm, so it can rotate in other dimensions too. That allows us to maximize the amount of radiation we can deliver and minimize exposure to other tissues.”
Beyond its movement capabilities, CyberKnife has other impressive features. For example, in most brain surgery cases the patient’s head needs to be immobilized using a frame that is fastened to the skull. Instead, the CyberKnife uses facial recognition software to adjust for any head movements. “It’s much more comfortable for the patient,” Dr. Grann says. For lung cancer treatments, the patient wears a vest that tracks respiration. “The machine turns off and on depending on the breathing cycle to target cancerous cells down to the smallest scale possible,” she says. And many cancer patients need just one to five treatments with CyberKnife, as opposed to six weeks of standard radiation therapy, with minimal risk to the kidneys and liver, which are dangerously close.
Some similar higher-dosage, shorterduration treatments are available right now. TomoTherapy, another radiation delivery device, has been offered at Saint Barnabas Medical Center for several years, Dr. Grann says. It adds precise and accurate targeting with up-to-the-minute computed tomography (CT) imaging. “The machine looks like a CT scanner but it also delivers radiation,” she says. “We can image the treatment area every day and make small adjustments if necessary.” Take, for example, a prostate cancer patient who needs a long course of treatment. “The prostate moves around a little bit every day, so a new image adjusts the target by perhaps two to three millimeters for better accuracy,” she says.
TomoTherapy is also especially helpful for cancers of the head and neck, which are located near critical, sensitive tissues. (See “The Cold That Wasn’t” on page 54.) The machine can be programmed for intensity-modulated radiation therapy (IMRT), which delivers maximum radiation to the target while modulating down when it gets near other tissues. “The margins—the spatial limits within which radiation can be delivered—are extraordinarily small, so we take the critical structures surrounding a tumor into account,” says Dr. Grann. “If a brain tumor is near the optic nerve, for instance, we tell the computer to place constraints around the optic nerve. The computer figures out how to maximize the dose to the tumor and protect the nerve.”
Other new weapons in the Medical Center’s arsenal include targeted, injectable treatments for cancers that have spread to other tissues. For colorectal cancer that has spread to the liver, her colleagues can inject radioactive particles into the hepatic artery that feeds the tumor. For prostate cancer that has spread to bone, a monthly injection in the arm of radium 223, while not a cure, has been shown to improve both quality of life and length of survival.
Saint Barnabas also has a large gynecological oncology program, and Dr. Grann says that a technique called brachytherapy, in which external radiation is combined with placing a radiation source internally, next to the tumor, is very successful at treating some forms of uterine and cervical cancers. “This takes a lot of skill and experience,” she says. “Here we treat cases with brachytherapy weekly, not twice a year like many other centers.”
She adds that radiation oncologists are also “becoming more sophisticated in working with our medical oncologist colleagues to come up with specific radiation sensitizers.” These are medicines that help increase the sensitivity of cancer cells to radiation, to potentially limit the dosages needed and increase cure rates.
Of course, there is more to treating disease than the skillful deployment of technology. “All of our physicians, physicists and dosimetrists have been highly trained at major academic centers, but they also make a point of treating every patient with compassion,” says Dr. Grann. “Our department’s physical environment is beautiful, warm and soothing, and we treat people, not diseases.”
For more information about the Radiation Oncology Department at Saint Barnabas Medical Center, please call 973.322.5630 or visit us online.