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

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 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 procedure.

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.

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