Patients with multiple myeloma and acute leukemia undergoing hematopoietic cell transplantation (HCT) tolerated higher doses of radiation and reported fewer side effects when they received targeted marrow irradiation (TMI) using TomoTherapy, researchers recently reported.
City of Hope researchers, who were the first in the nation to develop and test TMI, presented their findings at the 49th Annual Meeting of the American Society for Therapeutic Radiology and Oncology in Los Angeles. Through TMI, physicians administer radiation to patients from their head to their legs.
Researchers reported on 24 patients who received the investigational treatment as part of their transplant procedure through a clinical trial. All were successful, and no patient has experienced disease progression or cancer recurrence so far.
Multiple myeloma and acute leukemia are cancers of the bone marrow and blood. A hematopoietic cell transplant, also commonly known as a bone marrow transplant, offers prolonged remissions or possible cure for these diseases.
As part of the HCT procedure, patients receive chemotherapy or radiation — or both — to kill cancer cells. Then they receive new hematopoietic stem cells, which form the basis of a new immune system. Unfortunately, most multiple myeloma patients are older and have been unable to undergo HCT because their bodies cannot tolerate total body irradiation.
“Targeted marrow irradiation offers a new therapeutic agent to patients who need hematopoietic cell transplantation but who cannot tolerate treatment with standard total body irradiation,” said Jeffrey Wong, M.D., chair of the Division of Radiation Oncology and one of the principal investigators. “We are seeing in these studies that we are able to escalate doses beyond those possible with conventional total body irradiation, while reported side effects such as mucositis, diarrhea, nausea and vomiting are reduced.”
TomoTherapy machines incorporate spiral computed tomography scanning and external beam radiation to deliver controlled doses to targeted areas of the body. Instead of treating patients with wide beams of radiation across the whole body, radiation oncologists can use TomoTherapy to deliver therapy directly to the areas that need it — in this case bone marrow and lymph nodes — while reducing radiation to vital organs and healthy tissue in the surrounding areas.
“While the median follow-up time with these patients is short at 13.4 months, the data do suggest that TMI reduces short-term toxicities and that the targeted radiation doses do not seem to be detrimental to cancer outcomes,” said Wong. “The use of TomoTherapy and TMI provides full-intensity radiation therapy to where it’s needed most, and reduced intensity to where it’s not, which seems to result in an improved experience with fewer side effects.”
Physicians continue to study TMI to establish dosing levels and more completely identify the range of patients eligible for HCT procedures using TMI.