Sometimes women have more than one breast cancer in the same breast at the same time. These women are usually offered a mastectomy (removal of that breast) and breast reconstruction. It may be possible to treat these patients by removing each cancer using breast-saving surgery (lumpectomies), used for women with only one breast cancer. Databases show that women who had lumpectomies did well, but they may have been healthier before the surgery than those who had a mastectomy. The investigators need to be sure that lumpectomy is effective, safe, and acceptable for this patient group before making it universally available.

The investigators will run a small study to evaluate whether a sufficient number of eligible patients can be identified and are willing to accept randomisation of the interventions in question. Recruitment and compliance rates of which will inform the feasibility and design of a larger trial. This will comprise a multi-centre randomised controlled trial in women with Multiple Ipsilateral Breast cancer (MIBC) requiring surgery. Participants will receive either Therapeutic Mammoplasty (TM) following excision of each cancer focus or mastectomy (+/- reconstruction). Patients will be randomised (1:1) into either intervention or control group.Therapeutic mammoplasty is an operation to remove breast cancer(s) whilst also significantly reducing the size of the breast. Therapeutic mammoplasty can be used to remove more than one cancer in the breast using separate lumpectomies. Both skin and breast tissue are removed, leaving scars similar to those seen after a standard breast reduction. Each patient is followed up for 12 months post treatment with a total of 50 patients recruited. Timings of the follow-up visits are aligned with standard of care practice for this patient population with quality of life questionnaires and clinical photographs completed before and after surgery. Twenty women will also be invited to an optional semi-structured interview at twelve months.

Inclusion Criteria:

1. >40 years with MIBC, with the largest clinical cancer measuring 50mm as part of multifocal or multicentric "disease sites". 50mm may include the size of a single cancer and its surrounding small satellite cancers (6, 7). Clinically diagnosed (ultrasound and biopsy) either axillary lymph node negative or positive where axillary treatment depends on local policy
2. Two disease foci with a minimum of one invasive focus of breast cancer as defined within a "disease site"
3. Suitable for TM (best practice) using one large lumpectomy (multifocal) or any number of "distant" lumpectomies (multicentric) to excise "disease sites"
4. Fit for adjuvant therapy as per pre-operative evaluations (ECG, Chest X-ray, blood biochemistry)
5. Willing and able to provide written informed consent

Exclusion Criteria:

1. Neo-adjuvant therapy
2. Women considered high risk by local centre or known to have BRCA1/2 gene mutation
3. Ductal Carcinoma in situ (DCIS) only, and extensive DCIS
4. Bilateral breast cancers
5. Previous breast cancer (invasive or DCIS in either breast)
6. Pregnancy as confirmed on blood tests or ultrasound examination
7. Metastatic disease
8. Any previous type of breast radiotherapy
9. Significant other clinical risk factors and co-morbidities at the discretion of the treating clinicians
10. Previous or concomitant malignancy except adequately treated: non-melanomatous skin cancer; in situ carcinoma of the cervix and in situ melanoma

Study focuses on female breast cancer

All requests for data sharing will adhere to the UCL Surgical & Interventional Trials Unit (SITU) data sharing agreement policy. UCL Medical School is supportive of data sharing and will endeavour to assist in requests for data sharing. These data will be held on secure servers and will not be released to any third parties until all the main outputs from the studies have been published. All requests for access to the data will be formally requested through the use of a SITU data request form which will state the purpose, analysis and publication plans together with the named collaborators. All requests are dealt with on a case by case basis by SITU and the Chief Investigator. All requests will be logged and those successful will have a data transfer agreement which will specify appropriate acknowledgement of the Chief Investigator and study group, the sponsor, and funders.

Neither the patients nor the clinical team will be blinded to the trial arms of this study