Screening programs and advances in imaging have led to more breast lesions being diagnosed at an impalpable stage. Multiple localisation techniques for nonpalpable breast lesions have been developed during the past decades. Specifically, several alternatives to the golden standard hooked-wire technique have become available, of which magnetic seed localisation is one of the newest approaches. Since September 2018, Magseed® localisation is the standard of care for localising impalpable breast lesions in UZ Leuven. In this study, the oncological safety, the clinical safety and surgeon satisfaction of Magseed® localisation will be assessed and retrospectively compared to hooked-wire localisation.

Inclusion Criteria:

• Breast conserving surgery with preoperative localisation
• Minimum 18 years old

Study population includes women (18+) with an impalpable breast lesion suitable for breast conserving surgery.