City of Hope radiation oncologists will develop technology that will bring targeted total body irradiation to patients at medical centers worldwide.
Varian Medical Systems, a leading manufacturer of radiotherapy systems, will support City of Hope researchers for several years, said Jeffrey Wong, M.D., chair of the Division of Radiation Oncology. Researchers will create and test ways to administer total body radiation using linear accelerator based intensitymodulated radiation therapy for the very first time.
“We’ll be doing the preclinical work required before clinical trials,” said Timothy E. Schultheiss, Ph.D., director of radiation physics, professor of radiation oncology and the project’s principal investigator. “We expect this technology to result in more precise treatment and fewer side effects.”
Intensity-modulated radiation therapy, called IMRT for short, is a precise way of administering therapeutic X-rays to patients. IMRT links imaging systems with high-energy X-ray machines to target radiation doses to cancerous tumors. Oncologists sculpt radiation to the tumor’s shape — and avoid healthy tissue — by modulating radiation beams’ intensity and pointing the beams from many different directions.
The technique already is complicated enough for single solid tumors, such as pancreatic cancer. Radiation oncologists and physicists must carefully create treatment plans using information from computed-tomography, or CT, imaging. But total body radiation raises the complexity bar even further: instead of fighting a single tumor, the treatment must span the entire body.
As Wong explained, the technology will benefit patients with cancers such as leukemia, lymphoma and myeloma who must rely on a hematopoietic cell transplant (HCT) to battle their disease.
Physicians use total body irradiation — beams of energy that cover patients from head to legs — to ablate patients’ immune systems and any remaining cancer cells during HCT. Patients then receive transplanted immune cells that grow into a new, healthy immune system.
However, Wong said, radiation only needs to cover the bone marrow and lymphatic system to do its job. Unfortunately, in standard treatment, radiation reaches other organs and can damage the kidneys, gastrointestinal system, lungs and other vulnerable areas. That may cause side effects such as nausea and vomiting. So radiation oncologists are trying to find ways to direct X-rays only where they are most needed.
Also, the physicians noted, patients receive traditional total-body irradiation standing up; but the new IMRT treatment would allow patients to lie more comfortably on a table.
In June 2005, City of Hope physicians performed the world’s first targeted total body treatment — called total marrow and lymphoid irradiation — using their TomoTherapy systems. TomoTherapy marries IMRT with spiral CT. But only certain medical centers have TomoTherapy systems. By creating a reliable method to perform total marrow and lymphoid irradiation using IMRT, City of Hope researchers hope to share the benefits of targeted radiotherapy with many more patients around the world.
The new grant will provide an additional treatment-planning computer and support a physicist. Khanh Nguyen, M.D., An Liu, Ph.D., and Wong are co-investigators.
The City of Hope team’s track record with targeted radiotherapy spawned the new grant, Wong said. The group began its preclinical studies of TomoTherapy for total marrow and lymphoid irradiation in 2002, and ushered in its first clinical trials of the technique in 2005.
Moreover, the group’s work with precisely targeted radiotherapy and TomoTherapy also led to plans for an international works-in-progress meeting on TomoTherapy at City of Hope, which is scheduled for autumn. And as construction gets under way on City of Hope’s new Center for Targeted Therapies, the Division of Radiation Oncology is approaching 17,000 total treatments with TomoTherapy since the first system was installed in November 2004.