Performance of sentinel lymph node biopsy after neoadjuvant chemotherapy in clinically node positive breast cancer patients: systematic review and meta-analysis

Background: The reliability of sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NACT) in patients with initially node-positive breast cancer is still controversial. This meta-analysis is conducted to investigate the feasibility and accuracy of SLNB after NACT in patients with initially positive axillary nodes. Methods: We conducted a literature search using Medline, PubMed, Embase, Central, and SCOPUS up until April 2021 for studies on the performance of SLNB following NACT. We included prospective studies including breast cancer patients with positive lymph nodes at diagnosis and received NACT before undergoing SLNB irrespective of their molecular subtypes or stage. Our main outcomes of interest were the identification rate (IR) and the false negative rate (FNR) of SLNB. Results: We included an aggregate of 33 studies in this meta-analysis enrolling 4,624 patients. The reported IR ranged from a minimum of 77.6% to a maximum of 100% and resulted in a pooled IR of 88% (95%CI: 86-90, I 2 :80.9%). The FNR reported in the studies ranged from a minimum of 5.1% to a maximum of 43% and showed a pooled FNR of 13% (95% CI: 11-15, I 2 : 72.31%). The subgroup analysis demonstrated that the usage of dual mapping technique could decrease the FNR and increase the IR. Moreover, the number of lymph nodes retrieved inversely correlated with FNR (p<0.01). Conclusion: Our findings support the feasibility and accuracy of SLNB after NACT in initially node-positive breast cancer patients, that converted to clinically node negative when performed in properly selected cases. SLNB offers a less invasive approach in selected patients sparing them the morbidity associated with ALND. This approach aligns with efforts to de-escalate surgical management in breast cancer and reinforces that SLNB post-NACT should be incorporated into clinical practice, provided that stringent patient selection and procedural standards are maintained.