This study will assess whether it is feasible to remove small breast cancers completely using the Vacuum Assisted Biopsy (VAB) system System under Ultrasound guidance.

Rationale: In the Netherlands, ≥7000 women undergo surgery for small breast cancers (T1) every year. In this study, the investigators will evaluate under which conditions it is possible to excise small breast cancers using the vacuum assisted biopsy (VAB) system under ultrasound (US) guidance. When successful, this can allow outpatient treatment of a selection of women with small breast cancers, improving the cosmetic outcome and quality of life.

Objective: Our study aim is to assess whether it is feasible to remove small breast cancers completely using the VAB system under US guidance.

Study design: This is a multi-centre, translational clinical phase II study in 170 women with cancers ≤15 mm based upon US and MRI measurements, and without mammographic or magnetic resonance imaging (MRI) evidence of more extensive disease (e.g. microcalcifications or non-mass enhancement).

Study population: Women with non-lobular invasive carcinomas, ≤15 mm based upon US and MRI measurements, no mammographic evidence of more extensive disease (e.g. microcalcifications or extensive architectural distortion), and sufficient space (roughly ≥6 mm, present or creatable by injection of saline) between the tumor and the dermis, nipple or pectoral muscle, are eligible for this study.

Intervention: In 170 women with cancers ≤15 mm based upon US and MRI measurements, and without mammographic evidence of more extensive disease (e.g. microcalcifications), after informed consent has been obtained, patients will be asked to fill out a questionnaire for assessment of breast cancer risk, using the Tyrer-Cuzick (or IBIS) model.

First, the tumor will be removed under local anesthesia using the VAB system with US guidance, through a small skin incision (<0.5 cm). A localization marker will be placed in the biopsy cavity, to help determine the cavity location. After 3 weeks, the breast conserving surgery is performed, excising the VAB excision cavity and a ≥1 cm of surrounding tissue, as deemed appropriate by the attending breast surgeon. A sentinel node biopsy will be performed in the same procedure.

Main study parameters/endpoints: Main endpoint of the study is the incidence of successful complete tumor excision by the VAB system, where successful is defined as having no tumor foci beyond 1 cm from the edge of the VAB cavity in the surgical re-excision specimen.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Our approach allows testing the feasibility of an innovating approach to remove breast cancer, with minimal negative effects or possible complications.

The burden from this study to the participating patients is the fact that two procedures are mandatory. This will result in prolonged time from initial diagnosis to end of surgical treatment. Positive study outcomes can pave the way to minimal invasive treatment in a selection of women, presenting with small breast tumors.

Inclusion Criteria:

• Female sex.
• 18 years or older.
• US visible breast cancer.
• Histologically proven non-lobular invasive breast carcinoma with maximum diameter of 15 mm as assessed by US.
• Willing and able to undergo preoperative breast MRI
• Able to fill out the questionnaire
• Able to provide informed consent.

Exclusion Criteria:

• Male sex.
• 17 years or younger.
• No proven invasive breast cancer.
• Poor US visibility of the breast cancer.
• Neoadjuvant therapy.
• Contra-indications to breast MRI or intravenous contrast administration.
• Unable to fill out the questionnaire
• Unable to provide informed consent.
• Patients with breast implants.
• Pregnancy.
• Presence of additional malignant lesions at ipsilateral site on MRI.