City of Hope radiation oncologists are now using TomoTherapy against pancreatic cancer – a particularly challenging disease to battle successfully – and physicians are seeing fewer side effects among patients as a result.
Radiation oncologists so far have treated seven City of Hope pancreatic cancer patients with the TomoTherapy Hi-Art System, said Yi-Jen Chen, M.D., Ph.D., clinical assistant professor of radiation oncology. All but one of the patients tolerated treatment so well that physicians believe they will be able to incorporate novel chemoradiation treatments in the future.
"We're seeing that with TomoTherapy, we're covering the tumor better, and at the same time, avoiding surrounding vulnerable areas," Chen said. "The end result is that we can better preserve patients' function and quality of life."
Through City of Hope's TomoTherapy system, radiation oncologists not only can administer therapy, but they also can create images through computed tomography (CT) to precisely target the tumor. The system integrates two features: spiral CT scanning and intensity modulated radiation therapy, or IMRT. Rather than using beams that hit the tumor from just one or two directions – as in conventional radiotherapy – TomoTherapy uses hundreds of pencil beams of radiation of varying intensity that rotate 360 degrees around a tumor while the patient moves through the machine.
In conventional radiation therapy, Chen said, not only is the tumor exposed to high doses of radiation, but surrounding healthy tissue unavoidably may be exposed, too. When a patient receives radiation therapy to treat a tumor in the pancreas, the beams also may reach the kidneys, small and large intestine, liver, stomach and spinal cord – causing damage and side effects such as nausea and vomiting.
Conversely, sometimes part of the tumor may not receive the full dose of radiation that it should.
In TomoTherapy, though, the high-dose region of radiation can be sculpted to fit the shape of each patient's tumor, resulting in more effective and targeted doses to the cancer.
"With this targeted approach, we see fewer side effects and an increased ability to combine radiation with chemotherapy," said Jeffrey Wong, M.D., chair of the Division of Radiation Oncology. Treatment simply becomes more tolerable.
And tolerability is a big issue for pancreatic cancer patients, whose cancer has usually grown and spread by the time it is found. As Chen explained, patients with pancreatic cancer fall into two categories: those with tumors whose size, spread and location allow for a surgeon to resect the cancer, and those with tumors considered inoperable. City of Hope physicians use TomoTherapy, together with chemotherapy, to treat both groups aggressively.
One recent patient exemplifies TomoTherapy's potential benefit, Chen noted. The elderly man was diagnosed with pancreatic cancer, and City of Hope surgeon Joshua D. I. Ellenhorn, M.D., associate professor of surgery, removed the malignancy using a Whipple procedure – one of the most grueling operations both for surgeons and the patients who must recover from it.
"At the tumor board, we were discussing his treatment and wondered if using chemotherapy and radiation therapy afterward would just be too much for him, considering his age and other factors," Chen said. "But with helical TomoTherapy, we thought, 'yes, of course, we should do this.'"
"He did so well that he was eating during his treatment, and was even asking me where he could get good Chinese food in this area."
Together with medical oncologist Stephen Shibata, M.D., director of City of Hope's Gastrointestinal Cancer program, Chen is proposing an investigational treatment protocol that would intensify treatment for patients with unresectable cancer. The physicians hope to use chemotherapy to sensitize the tumor to radiation, and, at the same time, provide a greater dose of radiation therapy through TomoTherapy. They would administer radiation to patients twice a day, rather than once a day.
Participating patients would finish their radiotherapy in three weeks rather than five weeks, allowing them to begin a course of systemic chemotherapy sooner.
"The success of our patients so far is what makes us believe we can compress the treatment to three weeks," said Chen, who noted that the multi-pronged attack against pancreatic cancer is only possible through the teamwork of surgery, medical oncology and radiation oncology at City of Hope.
Physicians are fervently pursuing more powerful tools to fight pancreatic cancer, which experts estimate will be diagnosed in 33,730 Americans this year. Another 32,300 Americans will die of the pernicious disease, according to the American Cancer Society, making pancreatic cancer the fourth-leading cause of cancer death.
