NEW YORK, Sep 30 (Reuters) -- A new type of radiation therapy is producing long-term treatment in nearly 4 out of 5 cases of non-Hodgkin's lymphoma, according to a recent study.
"We are encouraged by the long-lasting responses observed in many of our patients," write investigators at the University of Washington and the Fred Hutchinson Cancer Research Center, both located in Seattle. Their findings appear in the October issue of the Journal of Clinical Oncology.
According to the American Cancer Society, malignancies of the lymphatic system kill over 25,000 Americans every year. Non-Hodgkin's lymphomas comprise about 90% of all lymphoma cases.
Non-Hodgkin's lymphoma is most often treated by chemotherapy and radiation therapies, both of which have less-than-optimal cure rates along with serious side effects.
However, the Seattle researchers are now testing the effectiveness of a new type of radiation therapy called radioimmunotherapy. In this technique, patients are injected with a radioactive agent called iodine-131, which is 'piggybacked' onto a specific antibody. This antibody seeks out a protein found on the outside surface of lymphoma cancer cells. Therefore, when patients are injected with the iodine/antibody compound, the 'killer' molecule heads directly to its target -- tumor cells.
The Washington team followed the long-term medical histories of 29 non-Hodgkin's lymphoma patients receiving radioimmunotherapy.
They report that "23 (79%) of patients achieved complete responses (tumor elimination for at least one month), while another two attained partial responses." Most patients experienced gradual tumor shrinkage over a 3- to 6-month period, the authors say.
Twenty-two of the 29 patients are alive nearly 4 years after their initial radioimmunotherapy, the authors add, with 14 of those patients experiencing no further cancer progression. They say patients with relatively slow-growing tumors fared better than those with more aggressive cancers.
They add that "both short-term and long-term toxicities (adverse side effects) have been modest in most patients," with treatable thyroid dysfunction being the most likely side effect.
Despite the success rate associated with the treatment, the Seattle team believe "there is considerable room for improvement." Further studies will look at ways to enhance the ability of radioimmunotherapy to kill cancer cells, while "diminishing the exposure in normal tissues," the authors say. Other studies will look at the effectiveness of radioimmunotherapy in combination with various chemotherapies.
SOURCE: Journal of Clinical Oncology 1998;16.
