Abstract 202P
Background
According to guidelines, following primary systemic therapy (PST) a sentinel lymph node biopsy (SLNB) is preferable for patients with initial clinical and imaging-negative axilla. For patients with limited initial (biopsy proven) nodal involvement (cN1) who convert to negative, SLNB can be carried out. In all cases, any tumour deposits in SLNs prompt axillary lymph node dissection (ALND). The purpose of the study was to describe our series of breast cancer patients with SLNB following PST and to analyse residual nodal disease (RND) when sentinel node was positive.
Methods
Patients with breast cancers treated with PST at the University General Hospital of Alicante. SLNB post PST was performed by dual tracer mapping: Sienna+® magnetic tracer and technetium-99m (99mTc) sulphur colloid. Detection of metastases was performed by automated molecular assay (OSNA®). The SN tumour burden was classified as macrometastases (CK19 mRNA ≥5000 copies/ μl) or micrometastases (250–5000 copies/ μl).
Results
100 SLNB after PST were performed from March 2014 to June 2019. Median age was 45 years. Median follow-up was 34 months. Baseline characteristics were cT1: 11%, cT2: 77%, cT3: 12%, cN0: 67% and cN1: 33%. Pathological complete response was observed in 28 % of patients. In only one patient SLN could not be identified (Detection Rate of 99%). Of the remaining 99 patients, 2 or more SLN were identified in 87 (87.9%). 22 (22.2%) SLNB were positive, 8 (8.1%) for macrometastases and 14 (14.1%) for micrometastases. In these 22 patients ALND were performed. About the 8 cases with macrometastases we have identified RND in 3 patients (37,5%). However, in the micrometastases subgroup only was observed RND in 1 patient of 14 (7.1%), in form of micrometastases too. 3 patients had progression disease, 2 with distant metastases and 1 with locoregional recurrence. 1 patient had a second contralateral breast cancer.
Conclusions
In our study, high detection rate of SLNB after PST was observed. The procedure seems safe and worthy. Given the low rate of residual disease in the micrometastases subgroup, we could suggest avoiding axillary lymphadenectomy. Ongoing clinical trials will address this issue.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.