Radioactive Seeds Used to Help Prevent Local Recurrence of Non-Small-Cell Lung Cancer

CHICAGO--Implantation of iodine-125 seeds along the edges of a limitedsurgical resection can enhance local control of stage I non-small-celllung 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 ratesof 50% to 80% and a local recurrence rate of about 5%. Approximately 3%to 10% of patients with stage I NSCLC cannot undergo extensive surgicalresection, however, because of multiple medical problems or compromisedpulmonary function. The local recurrence rate for these individuals isbetween 15% and 30%, he said.

Radioactive iodine-125 seeds were implantedalong the surgical margin after wedge resection or segmentectomy in 12such patients at the New England Medical Center, Boston, in an attemptto decrease the extent of local recurrence, Dr. McGrath said.

There have been no local or regional recurrences after a median follow-upof 16.5 months, and a maximum follow-up of 37 months, he said. There wasonly one serious complication following seed implantation--one patientdeveloped a pulmonary embolism following a subsequent unrelated surgicalprocedure.

No patients have complained of worsened shortness of breath, and themean FEV-1 among five patients who had pre- and postoperative pulmonaryfunction 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 resectionwhile 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 effectivedose of radiation is delivered 1.0 cm to 1.5 cm from the resection margin.

Because the effective dose was concentrated directly adjacent to thetumor area, seed implantation reduced the volume of irradiated lung tissueby five times, thus sparing more normal lung tissue than would have beenthe case with external beam radiation therapy.