Goal of this observational study is to analyze data about cancer recurrence rates 5 and 10 years after primary breast cancer surgery with propofol or sevoflurane anesthesia. Only patients who were enrolled in the primary interventional trial can participate.

It has been assumed that the type of general anesthesia impacts the release of circulating tumor cells (CTC) in the perioperative setting of breast cancer surgery. Those CTC are suspected to promote metastasis formation. We have already investigated the direct effect of sevoflurane vs. propofol on CTC in a randomized controlled trial. There was no significant difference in the number of CTC between the two treatment groups up to 72 hours after anesthesia.

CTC are a surrogate marker for cancer recurrence. Therefore, the role of the choice of the general anesthetic for breast cancer surgery should be clarified focusing on the long-term clinical outcome. In this follow-up study, we aim at defining the cancer recurrence and overall survival in patients of the sevoflurane and propofol group of the primary clinical trial.

Inclusion Criteria:

• Only patients who consented and participated in the trial CEC N° 2016 - 01791 can be enrolled.
• GC must be available for patients with follow-up consultations at USZ.
• For patients with follow-up consultations outside of the USZ for those with unknown GC status, and for those who declined the GC, a study-specific written informed consent must be obtained, which will allow the research team to contact the responsible physician

Exclusion Criteria:

• Declined study-specific informed consent
• Inability to provide study-specific consent

Only patients who participated in the clinical trial (CEC 2016 - 01791) can be included into this study.

It is not yet known if there will be a plan to make IPD available.