Titanium clip placement to allow accurate tumour bed localisation following breast conserving surgery – Audit on behalf of the IMPORT Trial Management Group

IntroductionAccurate tumour bed (TB) localisation is a key requirement for the UK IMPORT (Intensity Modulated Partial Organ Radiotherapy) trial. We audited the value of titanium clips for TB localisation following breast conserving surgery (BCS) in breast radiotherapy (RT) planning.Patients and methodsAt surgery, paired clips were positioned around the TB as follows: 1. Medial, lateral, superior and inferior: half-way between skin and fascia; 2. Posterior: at the pectoral fascia; 3. Anterior: close to the suture line. Thirty consecutive patients with clips inserted were audited at the time of RT planning. Audit standards were set as follows: (i) 5/6 pairs of clips identified on RT planning computed tomography (CT) scan – 100%; (ii) possible clip migration: <10%; (iii) TB localisation improved with clips: >50%. Inter- and intra-observer variability in clinician outlining of the TB was studied in a subset of 12 randomly selected patients to see if this impacted on positioning of radiotherapy field borders.ResultsFive or six pairs of clips were identified in all 30 cases. The TB could be successfully identified using CT seroma alone in only 8/30 (27%) patients. Clips were essential for the TB localisation of the other 22/30 (73%) patients. There was no evidence of clip migration. TB localisation led to modified RT field borders in 18/30 (60%) patients. Five of these patients had highly visible seromas, so the addition of clips modified field borders in 13/30 (43%) patients. Both inter- and intra-observer variability was reasonable and did not impact on positioning of radiotherapy field borders.ConclusionTitanium clips provide an accurate and reliable method of TB localisation following BCS. We anticipate that the audit results will lead to clips being adopted as best practice by the Association of Breast Surgeons (ABS) at BASO (British Association of Surgical Oncology).