Intelligent Vacuum Assisted Biopsy Immediately Before Surgery As an Intra- or Pre-Operative Surrogate for Patient Response to Neoadjuvant Chemotherapy for Breast Cancer

Inclusion Criteria: * Written informed consent according to ICH/GCP regulations before registration and prior to any trial specific procedures * unifocal, histologically confirmed invasive breast cancer with IHC luminal B (with or without overexpression or amplification of the HER2 receptor) and all ER negative (ER \< 10%) breast cancers * Initial tumor size larger than 1 and less than 5 cm (cT1c to cT2), any N, M0 * Clipping of the primary tumor center prior to the start of neo-adjuvant chemotherapy * Neo-adjuvant chemotherapy resulting in a radiological complete response or near complete response on MR-Imaging (confirmed within 28 days before or on registration) as described in the trial specific MR-Imaging instructions (available on the welcome page of the study specific SecuTrial link). MRI is strongly recommended, alternative ultrasound * Former tumor bed must be accessible for biopsy * Female or male aged ≥ 18 years * Adequate condition for breast cancer surgery * Patients with a previously treated malignancy are eligible, when the risk of the prior malignancy interfering with either safety or efficacy endpoints is very low Exclusion criteria: * Metastatic breast cancer * Multifocal/Multicentric breast cancer * Inflammatory breast cancer * Luminal-A types of breast cancers (ER ≥ 10% and PgR ≥ 10 % and G1 or 2, and/or Ki-67 ≤ 20%, HER2 negative) or low risk if assessed by a validated genomic prognostic test (e.g. Mammaprint, Endopredict, Oncotype or Nanostring) * Distinct radiological sign of residual disease in the breast after neo-adjuvant chemotherapy by imaging * Intra-/peritumoral microcalcifications larger than 2 cm at time of diagnosis * Any local therapy (irradiation or surgery) to the currently treated breast prior to the trial intervention * Any other serious underlying medical, psychiatric, psychological, familial or geographical condition, which in the judgment of the investigator may interfere with the planned staging, trial intervention and follow-up, affect patient compliance or place the patient at high risk from trial intervention-related complications