The goal of this study is to assess patient satisfaction after oncoplastic breast conserving surgery. With the help of a breast-questionnaire the patient satisfaction will be assessed before the surgery and 4 weeks, 6 months and 1 year after the operation. The main question it aims to answer are: Does breast conserving surgery improve quality of life.

type of study: cohort study, observational

OCBS = oncoplastic breast conserving surgery BCT = breast conserving therapy DCIS = ductal carcinoma in situ

participant population/health conditions

• Patients with newly diagnosed breast cancer, that can be treated breast conserving
• the participants have to be at least 18 years old

Participants will fill out a questionnaire pre surgery, 4 weeks, 6 months and 1 year after the surgery. The individual questionnaires will be compared.

The management of breast cancer has undergone a significant shift over the last century. The advances in systemic therapy have not only improved the overall prognosis however also allowed for less radical surgery and more breast conservable efforts. The term oncoplastic breast conserving surgery was first coined in the early 90s where breast cancer surgery was performed while incorporating plastic surgical techniques. Therefore, this enabled the preservation of the natural breast shape with good aesthetic outcomes. Over the years oncoplastic breast conserving surgery has become widely accepted and adopted into routine clinical practice by most breast cancer surgeons. The oncological safety surrounding oncoplastic breast conserving surgery have been well established. Rates of positive surgical margins and re-excision rates have been shown to be similar to traditional lumpectomy operations. Complication rates are also comparable and oncoplastic breast conserving surgery does not result in delays in adjuvant treatments. However, many surgeons would concur that the most significant benefit of oncoplastic breast conserving surgery (OBCS) is patient satisfaction and the potential improvement in their quality of life.

Patient reported outcomes (PROMs) allow us to objectively assess patient satisfaction and the impact the intervention has had onto their lives. Incorporating PROMs into daily clinical practice would not only facilitate shared-decision making but also allow us to tailor clinical management to suit individual patient needs. This study however also aims to assess the patient reported outcome after breast surgery and in the follow up time (after radiotherapy, ...).

Inclusion Criteria:

• BCT oncoplastic surgery technique
• Women > 18 years

Exclusion Criteria:

• Previously treated ipsilateral breast cancer or DCIS
• Severe psychological illness by doctors' discretion (as taking part in a study could increase anxiety) or severe dementia, that stops them to consent to the procedure
• Pregnant women
• Distant metastatic disease (M1)

Patients from Brust-Zentrum Zürich undergoing oncoplastic breast surgery recruited between March and September 2023