Doctors at Providence Hospital Use Image-Guided Stereotactic Intensity-Modulated Radiotherapy to Target Spinal Tumors While Protecting Spinal Cord.
Advanced Technology From Varian Medical Systems Enables Clinicians to Zero in on Tumors and Avoid Surrounding Tissues.
Robert Gilbert, MD, radiation oncologist, recently treated a forty-eight year old man with lung cancer that had metastasized to the spine and brain.
"The patient's cancer was under control everywhere else," Dr. Gilbert said. "His brain lesion had been treated successfully at M. D. Anderson Cancer Center in Houston. Subsequent PET and MR scans showed that the only remaining active lesions were two in the spinal area. One of them was causing him a considerable amount of pain."
According to Dr. Gilbert, metastatic lesions, i.e. cancer that has spread to other organs away from the original tumor site, would have resulted in a rapid death not too long ago. "In many cases now," he said, "if the original tumor is well controlled using radiotherapy, chemotherapy, surgery, or some combination of these, we can use radiosurgery to address the metastatic lesions and offer these patients a much longer lifespan. There are some who will survive for many months, even years. We're seeing lung and brain cancer patients with metastatic disease living three or four years, and longer. That's because very recent advances in technology are enabling us to treat these metastatic lesions much more aggressively than we could have done before."
In the recent case, Dr. Gilbert had to be especially precise with the treatment, because the patient had already received some radiation in the spinal area. "The amount of radiation that the spinal cord can tolerate is pretty well known, and doctors must ensure that this amount is never exceeded," Dr. Gilbert said. "We are able to use image-guided intensity- modulated radiation therapy (IG-IMRT) to keep the dose away from the spinal cord while targeting lesions very close to it. The Trilogy machine is the perfect technology for just this kind of situation."
IMRT is a radiotherapy treatment approach that shapes and modulates the radiation beam so that it conforms to the shape of the tumor, and minimizes the dose to surrounding healthy tissues. Image-guided IMRT enables doctors to zero in on the tumor right at the moment of treatment to center it directly in the path of the shaped beam.
The protocol that Dr. Gilbert and his colleagues followed was pioneered by clinicians at Memorial-Sloan Kettering Cancer Center in New York, and written up in the May 2005 issue of the International Journal of Radiation Oncology Biology Physics. According to Gilbert, it involves five treatments over a five-day period, with one-fifth of the dose being delivered during each session.
"So far, the treatment has been well tolerated," Gilbert said. "A month and a half later, everything is okay. The patient isn't completely pain-free, but his pain has been significantly reduced. With other patients, we've seen complete relief."
"Before we had the Trilogy™ machine, we couldn't have achieved the precision his case necessitated," Gilbert said. "Now, with true image-guidance, we are comfortable treating down to the millimeter."
Although Providence Hospital is located in Mobile, Alabama -- one of the Gulf Coast cities affected by Hurricane Katrina in August -- the facility was not significantly damaged, and was able to continue caring for patients, and even to serve others from surrounding communities where the damage was greater. The hospital recently received a grant from the Lance Armstrong Foundation to assist cancer patients who have been displaced by the hurricane.
About 10,000 Americans develop primary or metastatic spinal cord tumors each year, according to the National Institute of Neurological Disorders and Stroke. Although spinal cord tumors affect people of all ages, they are most common in young and middle-aged adults.
