High Intensity Focused Ultrasound (HIFU) is a new method of treating solid tumours by thermally ablating them. It has been used in a number of different types of cancers but there is little information on its use in invasive breast cancer (IBC). The investigators aim to assess the efficacy and safety of HIFU in the treatment of IBC.

In this study, fifteen otherwise healthy women diagnosed with small, early stage IBC will be treated with HIFU prior to conventional surgical treatment. The effects of HIFU on the resected tumour will be analysed pathologically and correlated with radiological findings. Immune response and participant experience will also be evaluated

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the trial.
• Female, aged 18 years or above.
• Histologically confirmed breast cancer (invasive ductal cancer) by core biopsy, which is suitable for surgical resection.
• Participants must have one non-metastatic, clinically palpable, invasive breast cancer measuring ≤2cm in its largest dimension, which can be visualised using diagnostic ultrasound.
• All participants must have an adequate biopsy determination of oestrogen, progesterone, HER2 receptor status on pre-operative biopsy.
• Adequate ECG, haematological, renal and hepatic function, as indicated, as would be required for imaging and surgery.
• In the Investigator's opinion, is able and willing to comply with all trial requirements.

Exclusion Criteria:

• Female participant who is pregnant.
• Significant renal or hepatic impairment.
• An inadequate biopsy determination of oestrogen, progesterone, HER2 receptor status on pre-operative biopsy.
• Unable to visualize lesion or tumour boundaries clearly on ultrasound.
• Subjects with tumours lying less than 5mm to overlying skin or less than 5mm to the underlying muscle on the diagnostic scan.
• Any uncontrolled illness or any other medical problem that would preclude surgery.
• The presence of any contraindication for magnetic resonance imaging, e.g. the presence of a heart pacemaker, a metallic foreign body (metal sliver) in the eye, or an aneurysm clip in the brain or severe claustrophobia.