Irradiated beads offer palliative
option
Liver cancer responds to microsphere
treatment
By Jane Lowers
When surgery, chemoembolization, and radio-frequency ablation fail, patients
with hepatic tumors may respond to treatment with radioactive glass beads
delivered intra-arterially. Early data from the University of Maryland show that
the therapy is well tolerated, although data on improved survival or tumor
remission are unclear.
The 25-µm beads are embedded with beta radiation–emitting
yttrium-90, which has a half-life of 64 hours. The outpatient treatment follows
a screening angiogram to assess the portal vein. Additional imaging determines
whether arteries from the liver shunt into the lungs or could allow beads to
infiltrate the bowel mucosa. Either could cause serious complications.
The spheres are delivered by catheter to the entire liver. Doses are
calculated to give each patient 140 to 160 Gy radiation exposure, affecting only
tissue within 2.5 mm of the beads.
Of 30 patients treated since August 2000, seven have been readmitted to the
hospital for medical treatment of complications including nausea, vomiting,
sepsis, and hemoperitoneum. Five patients have died. Others have converted from
positive to negative PET scans, indicating some form of tumor regression. The
exact results are unclear, however, according to Dr. Ravi Murthy, lead
researcher.
"The results are preliminary but encouraging," said Murthy, director of
vascular and interventional radiology at Maryland. "This will never be a
first-line treatment competing with surgery, but it may become a second-line
treatment used in combination with other therapies."
Like other palliative options, the microsphere treatment can be repeated as
needed, Murthy said. Survival data appear to be comparable to or slightly better
than chemoembolization, although no direct comparisons of the two treatments
have been done in the U.S. Murthy expects to present data at the 2001 RSNA
meeting.
"This is new and the data are incomplete, but it seems to be working with
very low toxicity," he said.
