# Stabilised Hyaluronic Acid (sHA) gel as a novel marker for breast cancer tumour bed cavity: Surgical feasibility

## TL;DR

A new hyaluronic acid gel is tested as a safe and practical marker for breast cancer tumor beds to improve radiation therapy planning.

## Contribution

Stabilised hyaluronic acid (sHA) gel is introduced as a novel surgical marker for MRI-based radiation therapy planning after breast-conserving surgery.

## Key findings

- sHA gel insertion was successful in all 35 patients with minimal additional operating time.
- 89% of surgeons rated the procedure as 'easy' to perform.
- Adverse events occurred in 14% of patients but were consistent with standard breast-conserving surgery risks.

## Abstract

•Hyaluronic acid gel can be used to mark breast cancer tumour bed for MRI-based RT planning.•Hyaluronic acid gel is quick and easy to use.•Hyaluronic acid gel is safe to use.

Hyaluronic acid gel can be used to mark breast cancer tumour bed for MRI-based RT planning.

Hyaluronic acid gel is quick and easy to use.

Hyaluronic acid gel is safe to use.

Consistent delineation of the breast conserving surgery (BCS) tumour bed (TB) for breast cancer remains a challenge for radiation oncologists. Accurate delineation allows for better local control and reduces toxicity when planning partial breast or TB boost radiation therapy (RT).

In the operating theatre (OT) breast surgeons inserted stabilised hyaluronic acid (sHA) gel as small drops approximately one cm into the walls surrounding the resection cavity. Surgical feasibility was determined by the rate of successful sHA gel insertion procedure, the ease of insertion as rated by surgeons, the time required for insertion procedure, the quantity used, and any adverse events (AE) relating to sHA gel insertion.

Thirty-five patients were enrolled. All patients underwent sHA gel insertion successfully. The procedure added a median of 2.8 min to the OT time and was rated as ‘easy’ in 89 % of patients. There were no immediate AE in OT. Five (14 %) patients experienced a grade 2 or higher AE. Three of the five patients were prescribed oral antibiotics for breast infection. Two of the five patients experienced a grade 3 AE – haematoma which required evacuation in OT day 1 post-BCS, and infected seroma which required drainage and washout in OT 2 months post-BCS. All five patients recovered and underwent the planned adjuvant therapies for their BC. The AE data reflects common risks with standard BCS and are not clearly attributed to sHA gel insertion alone.

We show that sHA gel is surgically feasible as a marker to help define the TB cavity for post-BCS adjuvant MRI-based RT planning.