MAGNETO is a French medico-economic study on preoperative localization in breast cancer surgery. The main objective is to conduct a cost-consequence analysis comparing magnetic clip localization with the use of metallic wires for the preoperative identification of non-palpable breast lesions. The choice of localization method is left to the physician's and center's discretion. The study is non-interventional (with only questionnaires and data collection), prospective, and multicenter, with patient follow-up lasting up to six months after breast surgery.

The MAGNETO study is a non-interventional, prospective, and multicenter study. It includes two cohorts: one using magnetic clip localization and the other using metallic wire localization.

Patients are enrolled by the surgeon during the preoperative consultation validating the conservative surgery with preoperative localization. The choice of cohort is left to the discretion of the center based on their routine practice. Baseline data, including patient and disease characteristics, are collected.

Depending on the assigned cohort, localization is performed either with a magnetic clip or a metallic wire. A mammogram is then performed to assess the correct positioning of the marker and its distance from the target lesion. At this stage, the radiologist completes a Likert scale satisfaction questionnaire.

Breast-conserving surgery is performed according to the hospital's standard practices. On the day of the procedure, the surgeon also completes a Likert scale satisfaction questionnaire.

Patients complete quality of life (EQ-5D-5L) and satisfaction questionnaires at several points throughout the study. Postoperative complications are also recorded.

Inclusion Criteria:

• I1. Female aged ≥ 18 years;
• I2. Patient presenting with a unifocal and unilateral lesion of invasive carcinoma or in situ;
• I3. Indication for first breast-conserving treatment with the need for preoperative localization of the lesion, regardless of the associated lymph node procedure;
• I4. Patient affiliated with a health insurance system;
• I5. Non-opposition to the study.

Exclusion Criteria:

• E.1. Psychological, family, or sociological condition that may potentially compromise adherence to the treatment protocol and follow-up;
• E.2. Bilateral surgery required;
• E.3. Patient with metastatic breast cancer;
• E.4. Multifocal or benign lesions;
• E.5. Pregnant or breastfeeding patient;
• E.6. Need for neoadjuvant treatment;
• E.8. Patient under guardianship, curatorship, or deprived of liberty.

cisgender female with breast cancer

Patients recruited in 7 centers spread across France