Sentinel Node Biopsy in Patients With Breast Carcinoma Without Axillary Involvement at Diagnosis Receiving Primary Systemic Therapy

The purpose of this work is to try to elucidate the optimal time to perform SLNB in cN0 patients with BC. At the moment we do not have randomized trials that answer this question. With the current criteria for performing ALND after NAC, we have concluded that we benefit patients with Luminal phenotype if we perform SLNB prior to NAC.Background: Primary systemic therapy (PST) has acquired great importance in breast cancer (BC) in the last few years. In this scenario, even if it is accepted to perform SLNB before PST, most of the guidelines remark the advantages of this practice after it, such as avoiding another surgery to the patient, a rapid start of the treatment and no need of axillary dissection in cases of pathologic complete response (pCR). Nevertheless, the lack of knowledge of the initial axillary state and the need to practice axillary dissection with any axillary disease are claimed to be some other disadvantages. There are no randomized studies yet that can conclude the optimal timing of SLNB in PST, so for the moment we may settle for our common practice. Patients and Methods: We studied all the cases attended in the Breast Unit that joined the inclusion criteria between 2011 and 2019 in our hospital and we compared the group with SLNB before PST with the group with SLNB after PST in terms of unnecessary axillary dissection and description features. Results: We included 223 female patients diagnosed with BC and without clinical nor radiological axillary disease (cN0), who had received NAC and SLNB performed before or after it. We observed a higher proportion of high-grade histological tumors (G3), tumors with aggressive phenotypes (Basal like and Her 2 enriched), and younger women in the group of SLNB before NAC compared with the SLNB after NAC group ( P < .01). Despite this, we did not find any difference in the number of positive SLNBs or in the number of ALND performed between the 2 groups. We found a higher proportion of ALND with all the lymph node (LN) negatives in the SLNB before NAC group. Conclusion: Taking into account that in the observation period we did not use ACOSOG Z0011 criteria with all the SLNBs, we figure out what would have been the real results nowadays following these criteria. In this scenario we conclude that patients with luminal phenotype seemed to benefit from practicing SLNB before NAC in terms of avoiding axillary dissections. We could not make any conclusion in the rest of the phenotypes. However, prospective studies are needed to confirm if this affirmation could be proved.