Radioactive seed localization for nonpalpable breast lesions: review of 1,000 consecutive procedures at a single institution.

INTRODUCTION: Radioactive seed localization (RSL) is an alternative to wire localization for nonpalpable breast lesions, with reported lower rates of positive surgical margins. METHODS: A retrospective review of all consecutive RSL procedures performed at a single institution from 01/2003 through 10/2010 was conducted. RESULTS: One thousand RSL breast procedures were performed in 978 patients. Indications for RSL included invasive carcinoma (52%), in situ carcinoma (22%), atypical hyperplasia (11%), and suspicious percutaneous biopsy findings (15%). A total of 1,148 seeds were deployed using image guidance, with 76% placed ≥1 day before surgery. Most procedures (86%) utilized one seed. A negative margin was achieved at the first operation in 97% of patients with invasive carcinoma and 97% of patients with ductal carcinoma in situ (DCIS). An additional 9% of patients with invasive carcinoma and 19% of patients with DCIS had close (≤2 mm) margins, and underwent re-excision. Sentinel lymph node biopsy was successfully performed in 99.8% of cases. Adverse events included 3 seeds (0.3%) not deployed correctly on first attempt and 30 seeds (2.6%) displaced from the breast specimen during excision of the targeted lesion. All seeds were successfully retrieved, with no radiation safety concerns. Local recurrence rates were 0.9% for invasive breast cancer and 3% for DCIS after mean follow-up of 33 months. There was no evidence of a learning curve. CONCLUSIONS: RSL is a safe, effective procedure that is easy to learn, with a low incidence of positive/close margins. RSL should be considered as the method of choice for localization of nonpalpable breast lesions.

Radiation safety with use of I-125 seeds for localization of nonpalpable breast lesions.

RATIONALE AND OBJECTIVES: To describe radiation safety procedures for limiting exposures during localizing placement of iodine-125 (I-125) seeds in nonpalpable breast lesions. Radiation safety tasks included seed receipt, assay, sterilization, transfer, and placement; surgical localization and retrieval; and extraction of seeds by pathologists. Additional regulatory aspects included institutional review board approval, physician credentialing, off-label use, and governmental licensing. MATERIALS AND METHODS: Titanium seeds were assayed to ensure strength (1.85-5.55 MBq). Radiologists credentialed in mammography placed seeds with an 18-gauge needle under ultrasound or mammographic guidance. Surgeons located seeds with a hand-held, solid-state radiation detector. I-125 seeds were extracted from excised tissue and secured by pathologists. RESULTS: After the investigational phase, state permission was obtained for the institution's Radiation Safety Committee to oversee the clinical application of the procedure. In more than 300 procedures, all seeds and targeted lesions were removed successfully; more than 98% of patients had seeds removed within 24 hours. Mean diameter of excised specimens was about 4 cm, for a maximum dose to residual breast tissue of 2 cGy (approximately that of a two-view mammogram). Badge monitoring showed no loss of seeds and no increase in physician or technologist exposure. Radiation safety precautions facilitated safe handling. CONCLUSION: Clinically, the procedure has been accepted as routine, with standardized steps for safe and secure handling of radioactive seeds. Compared with conventional methods, use of I-125 seeds offers an improved method for localizing before surgical excision and has essentially replaced wire localization in our tertiary-care academic medical center.