126 - Radiofrequency Identification (RFID) Marker Localization in Non-Breast Tumors: A Safety and Outcomes Analysis

Purpose: Accurate localization of non-palpable tumors is critical for oncologic resection. While radiofrequency identification (RFID) marker localization is increasingly adopted in breast surgery {1,2}, its role in extra-mammary lesions remains underexplored. This study evaluated the safety, feasibility, and clinical outcomes of RFID (LOCalizer™, Hologic, Marlborough, MA) localization for non-breast tumors.

Materials and Methods: A retrospective review was performed of all RFID placements for surgical localization of non-breast tumors between 2020 and 2024. Eligible patients had histologically confirmed malignancy with metastatic/recurrent lesions requiring surgical excision. RFID tags were deployed by interventional radiologists or advanced practice providers under ultrasound or CT guidance using a 12-gauge introducer. Technical success was defined as tag deployment within/adjacent to the lesion on post-placement imaging. Migration was defined as > 5 mm displacement, and retrieval success as intraoperative identification and removal of the tag with the specimen. Data collected included demographics, tumor type, lesion size and depth, interval between placement and surgery, complications, and surgical margin status.

Results: Forty patients (mean age 65.9 ± 17.2 years; 52.5% male) underwent 48 RFID localization procedures. Lesion sites included lymph nodes (47.9%) and soft tissue/subcutaneous metastases (52.1%). Primary malignancies were predominantly melanoma (62.5%), followed by carcinoma (17.5%; ovarian n=3, breast n=2, cholangiocarcinoma n=2), sarcoma (15%; spindle cell n=2, Ewing's n=2, others n=2), and lymphoma (5%). Technical success was achieved in all procedures (100%). Tags were placed a median of 28 days prior to surgery (range: 1-134) with no increase in migration or retrieval failure over longer intervals. Procedure-related adverse events were limited to two minor hematomas (4.2%). One migration (2.1%) was observed without impact on surgical success. Intraoperative retrieval was confirmed in 95.8% of cases. Negative margins were achieved in 91.7% of resections, and only 4.2% required re-excision. Outcomes did not differ between ultrasound and CT guidance (p = 1.00).

Conclusion: RFID localization is a safe and effective technique for preoperative marking of non-breast tumors. It provides high intraoperative reliability, margin clearance, and minimal complication risk, with scheduling flexibility that facilitates complex oncologic workflows {3,4,5}. These results support broader adoption of RFID technology beyond breast applications.