Safety and efficacy of radioactive seed localization with I-125 prior to lumpectomy and/or excisional biopsy.

Purpose: To evaluate the safety and efficacy of pre-operative I-125 radioactive seed localization (RSL) as an alternative to wire localization (WL).

Methods: A waiver was granted by the institutional review board for this HIPAA compliant study. Review of 356 consecutive single site nonpalpable mammographic and ultrasound guided I-125 RSLs done between November 2011 and April 2012 was conducted. Preoperative mammograms and specimen radiographs were reviewed for seed-target distance, lesion location, and target/seed removal. During a brief surgical training period, 35 of 356 women had both RSL and wire localization (WL) of the same lesion. Chi-square and single sample t-tests were used to compare margin status and duration of procedures.

Results: Of the 356 RSLs, 303 (85.1%) were performed ≥ 1 day before surgery. Mammographic guidance was used in 330 (93%) and ultrasound in 26 (7%). Mean seed to target distance was 1mm (range 0-20mm); all targeted lesions were retrieved. In 31 women in whom mammographic guidance was used for both RSL and WL, median procedure time was not significantly different (RSL 9.0 min; WL 7.0 min; p=0.91), and median seed migration distance was <1mm (range 0-15 mm). No difference was detected between margin status with RSL alone versus WL (p=0.40 and p=0.65 for positive and <1mm margins, respectively). Two adverse events occurred requiring an additional wire/surgery.

Conclusion: RSL ≥ 1 day before surgery is a safe effective procedure for pre-operative localization, with few adverse events and surgical outcomes comparable to those achieved with wire localization.