Critères d'inclusion : 1. Patient aged 18 years or older.
2. Written informed consent provided.
3. Triple negative or HER2-positive / ER-negative or HER2-positive / ER-positive breast tumours.
4. Patients eligible for breast conservation after NAC.
5. Patients with T2-T3 N0 invasive breast cancer initially treated by NAC to allow
breast conservation, who have received a minimum of 6 cycles of adequate
NAC +/- anti-HER2.
6. Clinical complete response after NAC.
7. Radiological (mammography, breast US, breast MRI) complete response NAC.
8. Patients predicted to be node-negative at treatment initiation.
Critères de non-inclusion : 1. Patient younger than 18 years old.
2. Pregnant or breastfeeding women.
3. Proven metastatic axillary or internal mammary chain lymph node involvement
before NAC proven by biopsy or cytology.
4. Bilateral breast cancer.
5. Contraindication to MRI.
6. Contraindication to breast conservation
7. Patients with a BRCA mutation or other autosomal dominant high-penetrance
genetic predisposition to breast cancer.
8. Patients with limitation of freedom or under guardianship
9. Inability for psychological reasons
10. Hypersensitivity to local anaesthesia
11. Initial imaging showing ACR6 micro calcifications and/or ACR6 non-mass
enhancement associated to the index lesion