BACKGROUND:The necessity of performing a sentinel lymph node biopsy in patients with clinically and radiologically node-negative breast cancer after neoadjuvant chemotherapy has been questioned. The aim of this study was to determine the rate of nodal positivity in these patients and to identify clinicopathological features associated with lymph node metastasis after neoadjuvant chemotherapy (ypN+). METHODS:A retrospective multicentre study was performed. Patients with cT1-3 cN0 breast cancer who underwent sentinel lymph node biopsy after neoadjuvant chemotherapy between 2016 and 2021 were included. Negative nodal status was defined as the absence of palpable lymph nodes, and the absence of suspicious nodes on axillary ultrasonography, or the absence of tumour cells on axillary nodal fine needle aspiration or core biopsy. RESULTS:A total of 371 patients were analysed. Overall, 47 patients (12.7%) had a positive sentinel lymph node biopsy. Nodal positivity was identified in 22 patients (29.0%) with hormone receptor+/human epidermal growth factor receptor 2- tumours, 12 patients (13.8%) with hormone receptor+/human epidermal growth factor receptor 2+ tumours, 3 patients (5.6%) with hormone receptor-/human epidermal growth factor receptor 2+ tumours, and 10 patients (6.5%) with triple-negative breast cancer. Multivariable logistic regression analysis showed that multicentric disease was associated with a higher likelihood of ypN+ (OR 2.66, 95% c.i. 1.18 to 6.01; P = 0.018), whilst a radiological complete response in the breast was associated with a reduced likelihood of ypN+ (OR 0.10, 95% c.i. 0.02 to 0.42; P = 0.002), regardless of molecular subtype. Only 3% of patients who had a radiological complete response in the breast were ypN+. The majority of patients (85%) with a positive sentinel node proceeded to axillary lymph node dissection and 93% had N1 disease. CONCLUSION:The rate of sentinel lymph node positivity in patients who achieve a radiological complete response in the breast is exceptionally low for all molecular subtypes.

Despite improvements in chemotherapy, radiotherapy, and targeted therapy, surgery remains the cornerstone of curative treatment for breast cancer.Although the majority of patients are eligible for breast conservation, up to 40 per cent require (or choose) a mastectomy 1 .Mastectomy can have a negative impact on body image, and immediate breast reconstruction (IBR) can improve psychosocial well-being and quality of life [2][3][4] . Reconstructive techniqueBreast reconstruction may be either autologous, non-autologous, or a combination of the two.The most commonly performed techniques are tissue-expander implant reconstruction, direct to implant reconstruction, latissimus dorsi (LD) flap (with or without implant), and free lower abdominal tissue flap.Important considerations when choosing the most appropriate reconstructive technique include need for adjuvant treatment, surgical risk factors, body habitus, smoking status, and the contralateral breast (that is, need for symmetrizing surgery).Advantages of implant-based reconstruction include short operating time and fast recovery.This technique is best suited to patients with small-to-moderate size breasts with minimal ptosis, in whom radiotherapy is not indicated, or in those who require a bilateral mastectomy.Autologous reconstruction is the preferred option in patients with moderate-to-large ptotic breasts with suitable donor sites.This technique achieves a more natural appearance and better withstands the effects of radiotherapy than implant reconstruction.Relative contraindications to all types of immediate reconstruction include inflammatory breast cancer, as well as smoking and obesity owing to the increased risk of flap necrosis and wound healing issues 5,6 .

Background: Some indeterminate breast lesions are considered high risk due to their potential association with malignancy. It is recommended that a diagnostic excision is performed when such high-risk lesions are diagnosed. While it is accepted that these women are at higher risk of developing breast cancer in the future, there is limited data on long term outcomes of women with this diagnosis.

Abstract Introduction Magnetic seeds (Magseeds) are becoming increasingly used as a method of localising non-palpable breast lesions. The cost effectiveness and reduced scheduling conflicts in comparison with wire localization has led to increased popularity in recent years. There's a paucity of data on outcomes when using multiple magseeds in one breast. In this study, we assess the radiological, operative and pathological outcomes of inserting multiple magseeds in the same breast. Methods A retrospective analysis of all magseed guided excisions preformed at the MMUH breast surgery department between January 2020 and December 2022. 40 patients with more than one magseed inserted unilaterally were included. Primary outcome measures were successful excision of lesion(s) and magseed retrieval. Secondary outcomes included re-excision rate and perioperative complications. Results The mean distance between magseeds was 48.3 and 42.5 mm on ML and CC views respectively. 9/40 used magseeds for bracketing while the rest used for excision of discrete lesions. Mean operative time was 56.65 minutes and 55% of the procedures were wide local excisions. There was no reported difficulties identifying magseeds intra-operatively or in the specimen mammogram. The mean specimen size is 33.42 mm while the mean size of the final lesion is 15.49 mm. Invasive ductal carcinoma was the commonest pathological outcome. The rate of positive margins was 20% and re-excision was 15%. One patient proceeded to completion mastectomy. Conclusion Multiple magseed localisation is a feasible, safe and effective method when utilized in bracketing a unifocal lesion or separate lesion excisions in unilateral breast surgery.

e12571 Background: There is increasing reliance on data provided by genomic risk assessment assays to guide therapeutic decisions. The objective of this prospective study was to assess the impact of the Oncotype DX Breast DCIS Score assay on radiation treatment recommendations in patients with DCIS undergoing BCS. Methods: This decision impact study is a prospectively enrolled observational study of newly diagnosed patients (n = 135) following BCS for removal of DCIS of all grades 30mm or less with clear margins (i.e. 2 mm or normal re-excised margins). Only patients who were candidates to receive radiation therapy were considered. Fifteen patients withdrew from the study or had insufficient volume of DCIS for assay analysis. Radiation Oncologists were blinded to the Oncotype DX Breast DCIS Score assay prior to recording their recommendation for radiotherapy or not. IRB approval was granted following review of study protocol and informed consent was obtained from all patients. Results: Among 120 patients tested, the Oncotype DX Breast DCIS Score assay determined that 58/120 (48.3%) of patients had a low score (LS) (0-38), 30/120 (25%) had an intermediate score (IS) (39-54) and 32/120 (26.7%) had a high score (HS) (>55). The Oncotype DX Breast DCIS Score assay concurred with the Radiation Oncologists recommendation to proceed with radiation treatment in 96.7% of patients (i.e. 60/62 patients with an IS or HS). The Oncotype DX Breast DCIS Score assay altered treatment decisions in 12.5% (4/32) of patients with a HS and in 7.1% (2/28) patient with an IS. In patients where the Oncotype DX Breast DCIS Score assay altered treatment recommendation all had a low volume (i.e. less than 10mm) of high/intermediate grade DCIS with an IS or HS. Conclusions: This study demonstrates that Oncotype DX Breast DCIS Score assay accurately supports the selection of patients with DCIS for radiation treatment and equally can be helpful in selecting a subgroup of patients with small volumes of intermediate/high grade DCIS who can potentially avoid radiotherapy.

Abstract Aim Patients presenting with a palpable breast lump with normal imaging presents an investigative challenge. While the reported sensitivity of US and mammogram is high, radiologically occult cancers do occur. Traditionally these patients have undergone clinical core biopsy. The aim of our study was to examine the use of clinical core biopsy in our department over a 10-year period and assess its efficacy in diagnosing radiographically occult malignancies. Method We performed a retrospective review of a prospectively maintained database of all clinical core biopsies performed from 2010–2019 in a symptomatic tertiary breast cancer unit. Patients who underwent fine needle aspiration or skin punch biopsy without breast clinical core biopsy were excluded. A number of patients underwent clinical core biopsy despite abnormal radiological findings for clinical reasons, these patients were excluded from the final analysis. Clinical examination findings, radiological findings and ultimate pathological findings were reviewed. Results 370 clinical core breast biopsies were performed over the study period. 11 patients were excluded as they underwent clinical biopsies despite abnormal imaging. Of the remaining 359 biopsies, 349 (97.21%) were benign and 9 (2.51%) required further investigation. Of these patients, 6 underwent excisional biopsy with one patient being diagnosed with DCIS. The remaining excisional biopsies were benign. 1 patient (0.29%) with normal imaging was diagnosed with a malignancy on clinical core biopsy. Conclusions The management of patients with palpable breast lumps despite normal imaging is challenging. Clinical core biopsy, in the context of normal imaging, has a low rate of detection of malignancy.

Background: In recent years there has been a resurgence in the use of the pre-pectoral implant breast reconstruction (IBR) with favourable reported outcomes. Most studies have reported the use of biological mesh. TIGR® mesh is a synthetic cheaper alternative. The aim is to establish the outcome of an Irish cohort of patients who underwent pre-pectoral immediate implant reconstruction using TIGR® mesh.

INTRODUCTION:Atypical intraductal epithelial proliferation (AIDEP) is a breast lesion categorised as "indeterminate" if identified on core needle biopsy (CNB). The rate at which these lesions are upgraded following diagnostic excision varies in the literature. Women diagnosed with AIDEP are thought to be at increased risk of breast cancer. Our aim was to identify the rate of upgrade to invasive or in situ carcinoma in a group of patients diagnosed with AIDEP on screening mammography and to quantify their risk of subsequent breast cancer.METHODS:We conducted a retrospective review of a prospectively maintained database containing all patients diagnosed with AIDEP on CNB between 2005 and 2012 in an Irish breast screening centre. Basic demographic data was collected along with details of the original CNB result, rate of upgrade to carcinoma and details of any subsequent cancer diagnoses.RESULTS:In total 113 patients were diagnosed with AIDEP on CNB during the study period. The upgrade rate on diagnostic excision was 28.3% (n = 32). 6.2% (n = 7) were upgraded to invasive cancer and 22.1% (n = 25) to DCIS. 81 patients were not upgraded on diagnostic excision and were offered 5 years of annual mammographic surveillance. 9.88% (8/81) of these patients went on to receive a subsequent diagnosis of malignancy. The mean time to diagnosis of these subsequent cancers was 65.41 months (range 20.18-145.21).CONCLUSION:Our data showing an upgrade rate of 28% to carcinoma reflects recently published data and we believe it supports the continued practice of excising AIDEP to exclude co-existing carcinoma.

Background: Invasive lobular carcinoma (ILC) accounts for approximately 10% of all breast cancers. It is more likely to be multifocal, bilateral and mammographically occult than invasive ductal carcinoma. MRI is sometimes warranted to assess the extent of disease but its routine use in ILC is controversial. The aim of this study was to assess MRI use and its impact on surgical decision making in a modern cohort of Irish women with a diagnosis of ILC.

Background: Phyllodes tumours account for <1% of all primary breast tumours and carry a high risk of local recurrence. There is no consensus regarding acceptable margin width. Our aim was to analyse clinicopathological characteristics, surgical management and outcomes of phyllodes tumours. Methods: A retrospective review of a prospectively maintained database of patients who underwent surgery for phyllodes tumours in a single tertiary referral centre between 2007 and 2017 was performed. Patient demographics, tumor characteristics, surgical treatment and outcomes were analysed. Tumour margins were classified as positive (0 mm), close (≤2 mm) and clear (>2 mm). Results: Fifty-seven patients underwent surgical excision of phyllodes tumor. Median age was 37 years (range, 14–91 years). Forty-four (77%) were benign, 4 (7%) borderline and 9 (16%) malignant. Fifty-four patients had breast conserving surgery and 3 mastectomy. Thirty (53%) underwent re-excision of margins. The final margin was clear in 32 (56%), close in 13 (23%) and positive in 12 (21%). During a mean follow-up of 38.5 months (range, 0.5–133 months), 4 (7%) developed local recurrence. Two (5%) of the benign and 2 (22%) of the malignant phyllodes recurred. Two (17%) with positive final margin recurred, compared with 1 (8%) with close and 1 (3%) with clear final margin. Both patients with recurrent benign phyllodes had a positive final margin previously. Of the recurrent malignant phyllodes, 1 previously had a close and 1 a clear final margin. Conclusions: There are no guidelines for the surgical management and follow-up of phyllodes tumours. This data suggests that patients with malignant phyllodes and positive margins are more likely to develop local recurrence. Larger prospective studies are warranted to steer the development of guidelines.

Background: Breast cancer is diagnosed after the age of 65 in 44% of cases. There is controversy regarding the optimal management of breast cancer diagnosed after the age of 70. Our aim was to examine outcomes of a modern cohort of Irish women diagnosed with breast cancer aged ≥70 who underwent therapeutic surgery.

Introduction Lobular neoplasia is a term encompassing both atypical lobular hyperplasia and lobular carcinoma in situ. These pathological findings are of uncertain malignant potential and predispose to a higher lifetime risk of breast cancer. Debate surrounds the management of such lesions, with the rationale for diagnostic excision based on the possibility of upgrading to malignancy. In this study, we report the upgrade rate of these lesions and risk of subsequent development of breast cancer. Methods This is a retrospective review of a prospectively maintained data base of all biopsies of breast screening-detected abnormalities in a single Irish breast-screening unit. We included all patients with lobular neoplasia on core needle biopsy who underwent diagnostic excision from 2005 to 2012. We excluded those who had concurrent high-risk lesions on biopsy. End points included upgrade rate and subsequent diagnosis of malignancy on follow-up. Results During the study period, 66 patients met criteria for inclusion, with a mean age of 53.74 years. Upgrade rate following excision was 13.64% (n = 9/66). Of those not upgraded, 7.02% (n = 4/57) were subsequently diagnosed with malignancy. Median time to diagnosis was 59.61 months (range = 10.5-124.4). Conclusion There is a significant rate of upgrade following diagnostic excision of lobular neoplasia, supporting the practice of diagnostic excision. There is an increased lifetime risk of breast cancer for women with a diagnosis of lobular neoplasia, with many of these cancers occurring outside the standard five-year monitoring period, suggesting a potential benefit in extending surveillance.

INTRODUCTION:Phyllodes tumours represent 0.3-1% of breast tumours, typically presenting in women aged 35-55 years. They are classified into benign, borderline and malignant grades and exhibit a spectrum of features. There is significant debate surrounding the optimal management of phyllodes tumour, particularly regarding appropriate margins.METHODS:This is a retrospective review of a prospectively maintained database of patients who underwent surgical management for phyllodes tumours in a single tertiary referral centre from 2007-2017. Patient demographics, tumour characteristics, surgical treatment and follow-up data were analysed. Tumour margins were classified as positive (0 mm), close (≤2 mm) and clear (>2 mm).RESULTS:A total of 57 patients underwent surgical excision of a phyllodes tumour. The Mean age was 37.7 years (range: ages 14-91) with mean follow-up of 38.5 months (range: 0.5-133 months). There were 44 (77%) benign, 4 (7%) borderline and 9 (16%) malignant phyllodes cases. 54 patients had breast conserving surgery (BCS) and 3 underwent mastectomy. 30 (53%) patients underwent re-excision of margins. The final margin status was clear in 32 (56%), close in 13 (23%) and positive in 12 (21%). During follow-up, 4 patients were diagnosed with local recurrence (2 malignant, 1 borderline and 1 benign pathology on recurrence samples).CONCLUSION:There are no clear guidelines for the surgical management and follow-up of phyllodes tumours. This study suggests that patients with malignant phyllodes and positive margins are more likely to develop local recurrence. There is a need for large prospective studies to guide the development of future guidelines.

Background: Excision is currently recommended for all B3 lesions in Ireland. Reported rates of upgrade vary widely in the literature. The aim of this study was to determine the rate of upgrade of various screening-detected high risk breast lesions diagnosed by CNB in a cohort of Irish women.

Purpose Radial scars and complex sclerosing lesions of the breast are part of a group of "indeterminate" breast lesions, which are excised due to risk of coexistent carcinoma. The aim of this study was to assess rate of upgrade of these lesions to invasive and in situ carcinoma and to quantify the risk of development of subsequent cancer in women diagnosed with these lesions. Methods A retrospective review of a prospectively maintained breast screening database was performed. All patients with radial scar identified at either core biopsy or final excision biopsy between January 2006 and July 2012 were identified. Full pathological reports for both core biopsy and final excision biopsy were reviewed. Patient outcomes were followed for a mean of 117.1 months. Results Of 451 B3 biopsies performed at our screening unit, 95 (22%) were found to have a radial scar or complex sclerosing lesion (CSL) on core needle biopsy. Within this group, 77 had no atypia on CNB, with 7 (9%) upgraded to invasive/in situ carcinoma on final excision. Of nine with definite atypia on CNB, 3 (33%) were upgraded. In those patients without atypia or malignancy on final excision, 7.5% developed cancer during 10-year follow-up. Conclusion Patients with radial scar with atypia have a higher risk of upgrade to malignancy. Further research is needed to identify which patients may safely avoid excision of radial scar. Patients with a diagnosis of radial scar on CNB are at increased subsequent risk of breast cancer and may benefit from additional screening.