Radiation therapy targeted at the cellular level can halt the
advance of lymphoma while avoiding the major drawbacks of chemotherapy,
according to a Stanford University study in the March 1996 issue
of Clinical Cancer Research.
The Stanford team used radioimmunotherapy (RIT) with yttrium-90
to treat 18 patients whose low- or medium-grade non-Hodgkin's
lymphoma had relapsed after chemotherapy. The patients were not
candidates for conventional bone marrow transplants because of
the extent of their disease.
The researchers observed significant tumor regression in 13 patients
and complete disappearance of the tumors in 6 of the 13. The primary
side effect of the treatment was temporarily decreased blood counts,
but other side effects of chemotherapy, such as hair loss, weight
loss, and nausea, were not observed. Freedom from disease progression
lasted for periods ranging from 3 months to more than 29 months.
"Our patients appreciated the mildness of this treatment
compared with chemotherapy," said Dr. Susan Knox, an assistant
professor of radiation oncology at Stanford and lead author of
the paper. "Not only did it work better for most of the patients
than their prior chemotherapy, but they felt well for the most
"Chemotherapy often can make people feel quite sick,"
Knox said. "Our patients didn't feel sick. They continued
to work, ride horses, play golf and do their normal activities."
Chemotherapy performed on an outpatient basis is frequently the
preferred treatment for patients with lymphoma. Chemotherapy can
eventually lose its effectiveness in low-grade lymphomas, however,
which are more indolent than higher grades of lymphoma but often
incurable, Knox said.
Radiation does kill the cancerous cells and can be targeted at
them using RIT. This form of radiation therapy delivers radiation
directly to the cancer using monoclonal antibodies with attached
radioisotopes. The antibodies recognize and bind to targets on
cancer cells. When they are injected into a patient's system,
the antibodies help concentrate the therapeutic radiation in the
Currently, RIT with yttrium-90 is being evaluated as a treatment
alternative in cases where chemotherapy has failed. More studies
will be necessary, Knox said, to learn how best to use this new
Knox is hopeful that RIT with yttrium-90-labeled antibodies will
eventually be an outpatient treatment. Chemotherapy is administered
on either an outpatient or inpatient basis, depending on the particular
drugs used, she said.
The Stanford study was a phase I/II study to evaluate safety as
well as effectiveness of RIT with yttrium-90, Knox said. A multicenter
phase II study is already in the works; it will provide a larger
sample for a true measure of treatment effectiveness. Eventually,
in a phase III study, the targeted radiation therapy will be compared
"That really is the definitive test," Knox said. "And
that will not happen for a while."
Coinvestigators on the Stanford team headed by Knox included Dr.
Ronald Levy, professor of medicine and chief of the division of
oncology; Dr. Michael Goris, professor of radiology and nuclear
medicine; and Dr. Thomas Davis, medical oncology fellow.