Multiple myeloma patients receiving tandem-high dose therapy may face fewer and less debilitating side effects through total marrow irradiation than through total body irradiation, according to City of Hope researchers.
City of Hope hematologists and radiation oncologists presented data from their study using total marrow irradiation in tandem therapy at the 2007 American Society of Clinical Oncology Annual Meeting.
Multiple myeloma is a cancer of the plasma cells, immune cells that produce antibodies to help fight infection and disease. Physicians usually begin treatment with chemotherapy to control the disease and lessen symptoms. Single- or tandem-high dose therapy may follow.
Investigational tandem-high dose therapy for multiple myeloma involves a round of highdose chemotherapy followed by hematopoietic cell transplantation, or HCT. Six weeks later, physicians administer more chemotherapy — with or without high-dose radiation — followed by a second HCT.
Traditional radiation therapy used in this treatment — called total body irradiation, or TBI — exposes all of the body to energy beams to try to eradicate remaining cancerous cells. However, patients may experience serious side effects from TBI, which can limit treatment. But City of Hope’s TomoTherapy Hi-Art systems allow radiation oncologists to target beams specifically to bone marrow, where radiation is needed, while limiting exposure to the rest of the body. This investigational technique is called total marrow irradiation, or TMI.
With less radiation damage to healthy organs, patients may experience fewer or lessened side effects, such as fatigue, low white blood cell counts and loss of appetite.
“Attempts to combine TBI with high-dose chemotherapy can result in substantial organ toxicities, which may preclude us from delivering the optimal dose of chemotherapy,” said George Somlo, M.D., director of the Multiple Myeloma Program in the Division of Hematology & Hematopoietic Cell Transplantation. “Our study results indicate TMI may be a useful addition to tandem-high dose therapy for patients with multiple myeloma.”
City of Hope conducted the world’s first TMI and continues evaluating TMI through clinical trials.
Sixteen patients with stage 2 or 3 multiple myeloma enrolled in the trial and were treated with varying levels of radiation. Through TomoTherapy, the median radiation dose to healthy organs was only 15 to 60 percent of the dose to bone marrow. Patients generally tolerated TMI better and experienced fewer side effects than with TBI. All conditions were reversible.
Somlo, who also directs the Breast Oncology and High Dose Therapeutics program in the Division of Medical Oncology & Therapeutics Research, led the study with Jeffrey Wong, M.D., chair of the Division of Radiation Oncology. “The results are encouraging and demonstrate the feasibility of using TomoTherapy to deliver TMI,” Wong said. “The reduced side effects observed are consistent with the reduced doses delivered to normal organs. Targeted TMI has the potential to improve the efficacy of tandemhigh dose therapy with higher possible doses of radiation and also improve the patient treatment experience by avoiding collateral toxicities and lessening side effects.”
Nearly 20,000 people will be diagnosed with multiple myeloma in the United States this year. Slightly more men develop the disease than women. About 11,000 people will die of the disease in the U.S. in 2007, according to the American Cancer Society.
