This is a pilot study to evaluate the feasibility of conducting a larger trial to determine if the use of intraoperative topical tranexamic acid (TXA) decreases the rate of post-operative hematomas and seromas in breast cancer patients after their mastectomy. In other words, the investigators want to determine if applying TXA inside the surgical wound before it is closed helps reduce blood or serous fluid accumulation at the operative site. Dependent on the results of this study, a further larger trial may or may not take place.

Post-operative seromas and hematomas are common complications of mastectomy surgery not only leading to infection, discomfort, wound dehiscence or emergency room visits; they also delay in some instances post-operative adjuvant radiotherapy. Establishing whether or not topical TXA is an effective strategy to decrease those complications can potentially impact positively the breast cancer treatment.

To achieve this aim, this randomized pilot study will first determine whether a larger multicenter study if feasible. This study will replicate a formal randomized trial at a smaller scale in a single center in order to assess the recruitment and randomization process, as well as provide preliminary results for our research question.

The objective of this study is to investigate the novel use of topical application of Tranexamic Acid (TXA) to the surgical wound as a means to decrease seroma and/or hematoma formation compared to placebo in post-mastectomy patients. This project is designed as a single-center pilot RCT to evaluate the feasibility of conducting a formal RCT (multicenter trial including more patients) to evaluate the effectiveness of topical TXA.

Patients will be randomly assigned to one of two treatment groups for intraoperative treatment of their mastectomy wound before it is closed.

The first group will consist of those who will be treated with the intravenous form of TXA that will be applied to the surface of the mastectomy wound area rather than being injected into a vein. The second group consists of those individuals who will be treated with a topical normal saline solution (a placebo, or inactive substance that looks identical to the study drug but contains no therapeutic ingredients).

Both groups will receive the same number of drains and the same post-operative follow-up schedule consisting of visits 2 to 4 weeks and 3 months after the surgery, as well as a last 12 months follow-up. Standard of care will be practiced with respect to all procedures and visits.

Inclusion Criteria:

• Breast cancer diagnosis
• Age 18-80
• Fluent in English
• Female undergoing mastectomy with or without axillary intervention

Exclusion Criteria:

• Immediate reconstruction
• Pre-surgical radiation
• Known allergy to TXA
• Known thromboembolic disease
• High-risk of thromboembolism and/or receiving anticoagulants
• History of myocardial infarction (MI), transient ischemic attack or stroke within the last year
• History of subarachnoid hemorrhage
• Premenopausal women with irregular menstrual bleeding of unknown cause
• Acquired disturbances of colour vision
• Hematuria with renal cause
• History of seizure disorder
• Pregnant or breastfeeding

Patients will be randomized on the REDCap system. Their assignment will be made available to pharmacy, which will be prepare syringes with either TXA or placebo.