Contouring Conformance comparing Barrigel® with Surgical Clips for Post-Lumpectomy Cavity Delineation in Breast Cancer

Participants with newly diagnosed early breast cancers planned for breast conserving surgery attend the hospital for surgery. In the operating theatre, following wide local excision of the breast cancer, the breast surgeon injects Barrigel (Non-animal stabilised hyaluronic acid gel) in the form of drops, with the goal to mark the deep and radial margins of the excision cavity. This involves drops (approximately 0.3 – 0.5 millilitres) injected using a sterile 21-23 gauge needle, starting at the base, injected just under the pectoral fascia at 4 points of the compass, indicating the deep margin. Further 4 drops are injected approximately 1cm interval above the base plane, also at 4 points of the compass, but at 1cm into the cavity wall, into the adjacent breast tissue. This is repeated at further 1cm intervals above the previous injection plane until the skin was reached. Standard surgical clips are also placed as markers at the same time to indicate the deep, radial and superficial margins of the excision cavity (approximately 4 to 6 clips are used). Following surgery and adequate recovery (approximately 1 to 2 months, or later if the participants undergo adjuvant chemotherapy), participants attend the radiation oncology outpatient department for CT and MRI simulation planning scans, in preparation for their adjuvant radiotherapy treatment. For the study, the scan images are de-identified and provided to radiation oncologists and radiologist to delineate the tumour bed aided by clips on CT, and gel on MRI. These are then further evaluated for consistency and other characteristics. The study participants' future surveillance breast imaging is then monitored for presence of the gel and its characteristics.