O081 De-escalating axillary dissection in mastectomy cases for ductal carcinoma in-situ

Abstract

Abstract Introduction Axillary surgery has been de-escalated in invasive breast carcinoma and may be omitted in certain age groups according to the Choosing Wisely initiative. Invasion can be found in 10-20% of patients with ductal carcinoma in-situ (DCIS). Therefore, Sentinel lymph node biopsy (SLNB) is indicated to rule out nodal metastasis. Our purpose was to study the risk factors and outcome of positive SLNB. Methods A retrospective analysis was performed on a series of 67 cases of patients who underwent mastectomy with SLNB for DCIS at Beaumont Hospital, Ireland, Royal College of Surgeons in Ireland, between 2015 and 2021. We evaluated their clinical, histopathological characteristics and regional recurrence. Results Only one invasive component was identified out of 67 cases (1.5%). Eight patients (11.9%) had positive SLN, six with isolated tumour cells, one micro-metastasis and one macro-metastasis. The three patients who proceeded for axillary lymph node dissection (ALND) presented with palpable lump, nipple discharge and through family history screening; however, all additional nodes retrieved were negative. All three patients had >5 cm high/intermediate grade disease. They were ER receptor positive and HER-2 negative. Regional recurrence was not reported in any. Conclusion This study identified a low rate of positive SLNB in DCIS and microinvasion on final histopathology. Factors which may increase the risk of positive SLNB are large tumours, palpable lump or nipple discharge. Our results indicate that ALND can be safely omitted in DCIS with positive SLNB but may be considered in high-risk patients.