CHAPEL HILL - By LESLIE H. LANG -This month, UNC became only the fourth U.S. medical center to use a mobile electron-based radiation therapy system to apply concentrated beams of radiation directly to a cancerous tumor site when it is surgically exposed.
"This means we can destroy malignant tissue while shielding the surrounding healthy tissue," said Dr. Joel E. Tepper, chair of the department of radiation oncology at the UNC School of Medicine and a member of the UNC Lineberger Comprehensive Cancer Center. "It also allows us to deliver a higher dose of radiation for greater effect, thereby increasing the odds of preventing cancer cells from reproducing. It may even reduce the need for weeks of outpatient radiation therapy."
Tepper is a pioneer in intraoperative radiation therapy, or IORT. He was among the first to use it in the United States 22 years ago at the National Cancer Institute. At Harvard, he helped further refine IORT before coming to UNC in 1987.
Since the mid-1980s, more than 11,000 people have been treated with conventional IORT, in which patients are wheeled out of surgery to the radiation oncology department where the procedure is performed. IORT has been applied to advanced and recurrent cancers of the head and neck, colon, uterus, cervix, bladder and intestines, as well as early stage breast cancer, stage III lung cancer, pediatric tumors and soft tissue sarcomas.
Now Tepper has joined an elite group of radiation oncologists to apply IORT via Mobetron, a mobile, self-shielded electron linear accelerator that can be wheeled into the operating room. The radiation system was developed by Intraop Medical Inc. of Santa Clara, Calif.
Tepper's first Mobetron IORT patient at UNC was a Raleigh-area man in his 50s, who received radiation during surgery for advanced colorectal cancer. He was selected for combination surgery-IORT by UNC's multidisciplinary gastrointestinal oncology team of surgical oncologists, medical oncologists, radiation oncologists and pathologists.
"He was felt to be an ideal candidate for this combined procedure," said surgeon Dr. William G. Cance, chief of surgical oncology at UNC. "The patient's cancer called for smaller margins of removal than the operating team would have liked. So we're boosting surgery with a two-minute dose of radiation."
Because it produces an electron beam rather than the photon beam of conventional X-ray methods, the Mobetron allows delivery of a larger dose of radiation safely to the patient. It also eliminates the risk associated with transporting patients from the OR to radiation oncology during surgery. Moreover, its design allows the system to move from one operating room to another.
Recent studies of IORT reveal significant increases in the five-year survival rate for patients with certain cancers. At the Mayo Clinic in Rochester, Minn., 46 percent of patients with advanced colorectal cancer who received IORT survived at least five years, compared to 24 percent of historical control group patients. The study also found that 19 percent of recurrent colorectal cancer patients who received IORT achieved five-year survival compared to only 7 percent of those who did not receive IORT.
"I think IORT with this mobile system has a lot of potential for patients with colorectal cancer, particularly for recurrent disease," Cance said. "And particularly in rectal cancer the amount of resection we can do is limited by vital body structures. Radiation allows us to get at a precisely focused area."
Tepper added: "IORT with the mobile system gives us more hope in difficult clinical situations. Now there's a better way to treat a range of malignancies, which means having greater optimism about their outcome."
