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 andprior to any trial specific procedures

• unifocal, histologically confirmed invasive breast cancer with IHC luminal B (withor 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 nearcomplete response on MR-Imaging (confirmed within 28 days before or on registration)as described in the trial specific MR-Imaging instructions (available on the welcomepage of the study specific SecuTrial link). MRI is strongly recommended, alternativeultrasound

• 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 theprior 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-adjuvantchemotherapy 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 tothe trial intervention

• Any other serious underlying medical, psychiatric, psychological, familial orgeographical condition, which in the judgment of the investigator may interfere withthe planned staging, trial intervention and follow-up, affect patient compliance orplace the patient at high risk from trial intervention-related complications