Diagnosis of Pathological Complete Response by Vacuum-assisted Biopsy After Neoadjuvant Chemotherapy in Breast Cancer

In clinical routine surgical treatment follows the pre-operative chemotherapy (NACT). However, recent studies have demonstrated that shrinking tumors need less surgical treatment indicating that patients with pCR could potentially be spared of surgery in the future. However, up to now, prediction of pCR after NACT is only moderately accurate. This prospective, monocenter diagnostic trial aims to explore if minimal invasive biopsies (MIB) might overcome this diagnostic challenge. Ultrasound guided VAB will be performed on 600 breast cancer patients after NACT and directly prior to surgery. There are only two trial visits that are specific to the trial. All other visits will be routine visits. 1. The first trial visit will take place in order to provide the patient with detailed information on the study, its' aims, the VAB procedure, and its risks. The patient will be asked to sign a form of informed consent. 2. At the second trial visit the performance of the VAB (=index test) will take place. This trial visit may vary by patient, tumor, and trial site characteristics and may either be: 1. An ultrasound guided VAB or 2. A stereotactically / mammographically guided VAB. All possible VAB procedures and settings (in outpatient clinic, or in operating room directly before the surgery) are equally accepted. We will allow every trial site to choose the adequate setting to the trial site´s and to their patients' needs. A visit for a follow up will not be necessary in this setting. Possible complications of the VAB procedure may occur while the biopsy is taken. The pathological results of the VAB specimen will be generally categorized as follows: 1. Residual tumor cells in VAB specimen (=non-pCR) 2. No residual tumor cells in the VAB specimen and VAB representative of former tumor region (="pCR in VAB") 3. No residual tumor cells in the VAB specimen but VAB unclear or not representative of former tumor region (=possible sampling error). These VABs are categorized as uninformative for the primary endpoint of the clinical trial. The results will be compared to those of the pathological examination of surgical specimen.