Timing of sentinel lymph node biopsy in patients receiving neoadjuvant chemotherapy for breast cancer.

Objective: To address optimal timing of sentinel lymph node biopsy (SLNB) in breast cancer patients undergoing neoadjuvant treatment.

Methods: The study population included 117 patients with locally advanced cancer with clinically negative nodes treated with primary chemotherapy. Group 1 underwent SLNB and completion axillary lymph node dissection (ALND) in conjunction with lumpectomy/mastectomy, after neoadjuvant treatment (n = 31). Group 2 underwent SLNB followed by neoadjuvant therapy and subsequently surgery and completion of ALNDs (n = 58). Group 3 was treated using the same sequence as group 2, however, completion ALND was performed only for patients with positive sentinel lymph nodes (SLNs) (n = 28).

Results: SLN identification was lowest in group 1 compared to groups 2 and 3 (87% and 98.8% respectively; P = <0.05). The highest false negative rate was in group 1 (15.8% compared with 0% in group 2).

Conclusions: Neoadjuvant treatment lowers the SLN identification rate, possibly due to fibrosis within the axilla, and increases the false negative rate due to downstaging. SLN biopsy prior to chemotherapy could give a more accurate evaluation of axillary status, unaffected by any previous therapeutic intervention.