P029. Does micro-invasion with DCIS on core biopsy from breast patients indicate whether sentinel lymph node biopsy (SLNB) should be performed?

S S35 and 23% respectively). 5 patients (8%) had a >50% reduction from their initial imaging to final histological size. 3 patients (5%) showed a complete radiological response however none showed a complete histological response. 39 patients were offered breast-conserving surgery (36 WLE, 3 therapeutic mammoplasty), of which 8 required re-excision of margins (30% in 30mm tumours). Only one patient needed a completionmastectomy. Only one patient had a local recurrence after negative margins at WLE (1.5%). Conclusion: Breast conserving surgery continues to provide good surgical outcomes for invasive breast cancers but patients should be counselled about risks of incomplete excision. Neoadjuvant treatment is effective in debulking tumours pre-operatively and is suggested to have a greater effect on larger disease. In our data, smaller tumours of <20mm diameter were more likely to require re-excision of margins compared to tumours between 20e30mm following neoadjuvant letrazole. http://dx.doi.org/10.1016/j.ejso.2015.03.064 P028. Comparison of three acellular collagen matrix materials to assist implant-based breast reconstruction Matthew Barber Edinburgh Breast Unit, Edinburgh, UK Introduction: The Edinburgh Breast Unit performed 419 implantbased breast reconstructions assisted by the use of acellular collagen matrix (ACM) between July 2008 and July 2014. Three types of matrix have been used for 402 of these procedures. The present study aimed to compare the use and outcome of Permacol, Strattice and Veritas to assist implantbased breast reconstruction. Methods: Cases of implant-based breast reconstruction using Permacol, Strattice and Veritas ACMs performed in Edinburgh were analysed with 6 months follow up. Results: Permacol (P), Strattice (S) and Veritas (V) were used in 72, 220 and 110 breast reconstructions respectively. Patient and breast weight, indications for mastectomy and proportion of bilateral cases did not differ between groups. Smoking, use of chemotherapy, incision used, associated axillary surgery, nipple preservation and use of fixed volume implant or expander did vary between groups apparently reflecting changes in practice over time. Rates of postoperative erythema varied significantly between groups (P 15.3%, S 7.7%, V 0.9%, chi 1⁄4 13.6, p 1⁄4 0.0011). Surgeons ranked materials V 1, S 2 and P 3 (chi-35.3, p < 0.0001). There was no difference in rates of unplanned surgery at 6 months (P 25%, S 27.7%, V 31.8%, chi 1⁄4 1.1, p 1⁄4 0.58) or implant loss at 6 months between groups (P 12.4%, S 11.4% and V 12.5% , chi 1⁄4 0.1, p 1⁄4 0.95). Conclusions: While differences exist in the characteristics of ACMs available to assist implant-based breast reconstruction and surgeons have clear preferences, there were no differences in outcome in terms of failure rate or unplanned reoperations in the present study. http://dx.doi.org/10.1016/j.ejso.2015.03.065 P029. Does micro-invasion with DCIS on core biopsy from breast patients indicate whether sentinel lymph node biopsy (SLNB) should be performed? Susan Hignett, Catherine Tait, Kathryn Rigby, Pauline Carder, Richard Linforth, Mohamed Salhab 1 Bradford Teaching Hospital NHS Foundation Trust, Breast Department, Bradford, UK Bradford Teaching Hospital Foundation Trust, Histopathology Department, Bradford, UK Introduction: The significance of micro-invasion on pre-operative core / Vacuum biopsy performed on breast patients is unknown. The aim of this study is to determine whether SLNB performed in these patients adds any clinical significance. Methods: An analysis of treatment pathways was performed for consecutive breast patients with screen detected DCIS & micro-invasion confirmed on core/vacuum biopsy on the histopathology database. Results: 152 consecutive breast patients with DCIS on core biopsy were identified between January 2011eDecember 2014. 22 patients had confirmed micro-invasion associated with DCIS. 15 patients underwent wide local excision (WLE) & 7 had Mastectomy. Post-operative histology confirmed 12 (55%) patients with invasive disease, 3 patients with microinvasion & DCIS and 7 patients with DCIS alone. 14/22 (64%) had SLNB performed (median SLNB e 2 nodes), 12 at initial surgery (6 mastectomies & 6 WLE) and 2 were delayed based upon the final histology confirming invasive disease. Of the 6 undergoing WLE & SLNB; 4 patients underwent axillary staging as recommended by the Multi-Disciplinary Team and 2 were patient choice. Of all the SLNB, only 1 patient had micro-metastasis, the remainder were negative. Conclusions: All SLNB performed were noted to be negative, suggesting axillary staging has no clinical value in this patient group. This suggests patients can be safely managed avoiding the potential morbidity of SLNB. However, it is noted that 55% patients were found to have invasive disease on final histology, and would have required subsequent SLNB. This potentially has implications regarding the cost effectiveness for subsequent procedures. http://dx.doi.org/10.1016/j.ejso.2015.03.066 P030. Breast calcification: does size matter? A retrospective audit to identify the appropriateness of biopsy in small cluster breast microcalcification Debra Harris, Gillian Hutchison 1 North West School of Radiology, Manchester, UK Royal Bolton Hospital, Bolton, UK Introduction: Breast calcifications are calcium salt foci that may occur anywhere in breast tissue. They are normally non-palpable, asymptomatic and can indicate benign or malignant disease. They are increasingly diagnosed due to the NHS breast screening programme and the introduction of digital mammography. Increasing diagnosis has led to an increase in the number of stereotactic biopsies performed. These are a safe way to ensure sufficient tissue is obtained for diagnosis. Increasing biopsies lead to increasing workload and costs for units providing this service. This audit seeks to determine whether those screening mammograms containing calcification of less than 5mm go on to have benign pathology and could therefore avoid biopsy. Methods: Retrospective audit of all women recalled for stereotactic core biopsy following screening mammogram pick up of breast calcification less than 5mm during August 2012e2013 using NBSS database. Demographic data and pathological specimen results recorded. Results: Of 295 women biopsied, 70 had microcalcification less than 5mm. 37 patients with 4e5mm calcification were benign but 8 women with microcalcification 4e5mm had pathology of B3 or B5. 25 women with calcification 3mm or less showed benign pathological diagnoses. Conclusions: Number of biopsies performed could be reduced by 10% which equates to savings of £3000e6000 per year, additionally preventing anxiety surrounding further intervention. Further retrospective research needed to assess whether trends are similar with larger population. Stereotactic core biopsy could be avoided in screening population with breast microcalcification less than 3mm unless significant history; proving beneficial for the unit and the patient. http://dx.doi.org/10.1016/j.ejso.2015.03.068