Appearance of Stabilised Hyaluronic Acid Gel on Routine Surveillance Breast Imaging When Used to Mark the Post-Lumpectomy Tumour Bed in Breast Cancer.

INTRODUCTION: Stabilised hyaluronic acid (sHA) gel can be used as a breast cancer tumour bed marker. This study aimed to assess the gel on post-treatment surveillance mammography (MMG) and breast ultrasound (USS). METHODS: Patients who underwent breast-conserving surgery and adjuvant radiotherapy, with sHA gel markers (0.3-0.5 mL drops) in breast tissue had their routine 1- and 2-year post-treatment MMG and USS undergo central review by one experienced radiologist. The central review questionnaire included whether the gel was visible, description if visible, and whether it impacted diagnostic assessment of the images using a 5-point Likert scale. The images were also standardly reported by radiologists who were blinded to the gel history. RESULTS: Of the 33 patients eligible for evaluation, sHA gel was visible on the 1-year post-treatment MMG in 3% of patients, described as well circumscribed nodules adjacent to the surgical scar. sHA gel was visible on the 1-year post-treatment USS in 38% of patients, described as simple round cystic lesions near the surgical bed. sHA gel was still visible on the same patient's 2-year post-treatment MMG (3%) and was visible on the 2-year post-treatment USS in 19% of patients. In all cases, the gel was rated 'unlikely' or 'very unlikely' to impair diagnostic assessment of the images and did not lead to any additional investigations. The blinded radiologists reported the gel as non-suspicious appearing cysts without clinical concern. CONCLUSION: sHA gel used as breast tumour bed marker was not visible in most patients' post-treatment MMG and USS and did not affect diagnostic assessment.