CHICAGO--Implantation of iodine-125 seeds along the edges of a limited
surgical resection can enhance local control of stage I non-small-cell
lung carcinoma (NSCLC) in patients who cannot have more extensive surgery,
Jack McGrath, MD, said at the Radiological Society of North America meeting.
The standard of care of patients with stage I NSCLC, Dr. McGrath explained,
is lobectomy or pneumonectomy, which achieves five-year survival rates
of 50% to 80% and a local recurrence rate of about 5%. Approximately 3%
to 10% of patients with stage I NSCLC cannot undergo extensive surgical
resection, however, because of multiple medical problems or compromised
pulmonary function. The local recurrence rate for these individuals is
between 15% and 30%, he said.
Radioactive iodine-125 seeds were implanted
along the surgical margin after wedge resection or segmentectomy in 12
such patients at the New England Medical Center, Boston, in an attempt
to decrease the extent of local recurrence, Dr. McGrath said.
There have been no local or regional recurrences after a median follow-up
of 16.5 months, and a maximum follow-up of 37 months, he said. There was
only one serious complication following seed implantation--one patient
developed a pulmonary embolism following a subsequent unrelated surgical
No patients have complained of worsened shortness of breath, and the
mean FEV-1 among five patients who had pre- and postoperative pulmonary
function tests was not affected by surgical resection or seed implantation,
Dr. McGrath said.
In the procedure, two to three strands of radioactive iodine-125 seeds,
each with a mean activity of 10 mCi, are sewn along the margin of resection
while the lung is deflated.
The strands are placed 5 mm to 7 mm apart so that when the lung is re-expanded,
the separation between the strands is only about 1.0 cm and the effective
dose of radiation is delivered 1.0 cm to 1.5 cm from the resection margin.
Because the effective dose was concentrated directly adjacent to the
tumor area, seed implantation reduced the volume of irradiated lung tissue
by five times, thus sparing more normal lung tissue than would have been
the case with external beam radiation therapy.