Accuracy of sentinel lymph node biopsy in patients with large primary breast tumors

Background: Patients with large breast tumors are increasingly undergoing neoadjuvant treatment to downstage local disease; however, accurate staging of the axilla before the initiation of chemotherapy remains problematic. In the current study, the authors report on the accuracy of sentinel lymph node (SLN) biopsy in such patients to determine the feasibility of applying this technique before induction chemotherapy.

Methods: One hundred three patients with 104 tumors classified as American Joint Committee on Cancer (AJCC) T2 (tumor >/= 2 cm but </= 5 cm) or larger were recruited at the University of Pennsylvania and the Mayo Clinic. In the majority of cases, combined blue dye and radiotracer was used for SLN identification. After SLN identification, a completion axillary lymph node dissection was performed in 87 cases. The SLN was evaluated with hematoxylin and eosin and immunohistochemistry.

Results: The SLN was identified in 99% of cases. The overall rate of lymph node metastasis was 59% (95% exact confidence interval [95% CI], 49-68%) (61 of 104 cases). The SLN false-negative rate was 2% (95% exact CI, < 1-11.5%) (2 patients). In 56 tumors >/= 3 cm, 1 false-negative result (2% [95% exact CI, < 1-15%]) was identified, and the rate of lymph node metastasis was 62.5% (95% exact CI, 48. 5-75%) (35 of 56 tumors). Within 30 SLN positive patients with tumors >/= 3 cm and complete axillary lymph node dissection, 3 of 8 patients (37.5% [95% exact CI, 8.5-75.5%]) with micrometastasis (</= 2 mm) to the SLN had positive non-SLN compared with 21 of 22 patients (95.5% [95% exact CI, 77-100%]) with macrometastasis (> 2 mm) to the SLN (P = 0.002).

Conclusions: SLN biopsy for patients with large breast tumors is technically feasible and highly accurate. SLN biopsy should be considered for the staging of clinically negative axilla in patients scheduled to receive neoadjuvant chemotherapy.