Sentinel node biopsy before neoadjuvant chemotherapy for determining axillary status and treatment prognosis in locally advanced breast cancer

Background: Treatment of locally advanced breast cancer with neoadjuvant chemotherapy assesses an in vivo tumor response while increasing breast conservation. Axillary clearance of nodal disease after treatment defines prognostic stratification. Our study objective was to show that sentinel node staging before treatment can optimize posttreatment prognostic stratification in clinically NO patients. Methods: Eighty-nine patients with locally advanced breast cancer were treated with neoadjuvant chemotherapy. Of these, 42 (47%) clinically palpable or image-detected nodes (cN+) were histologically confirmed before treatment (group 1), and 47 (53%) patients without palpable lymph nodes (cN0) had a sentinel lymph node (SLN) biopsy before treatment (group 2). Survival analysis was conducted with the Kaplan-Meier method. Results: In groups 1 and 2, 82 (92%) of 89 patients had node-positive disease before treatment. Seven (8%) of 89 had negative SLNs and no completion axillary lymph node dissection, 24 (27%) patients had a complete pathologic axillary response (pCR^AX; 11 [26%] of 42 in group 1 and 13 [33%] of 40 in group 2), and 58 (65%) of 89 had residual disease in the axilla. Breast-conserving therapy was applied to 27 (30%) of 89 patients. The seven SLN-negative patients had no axillary recurrence at 25 months, and pCR^AX patients had a significantly higher overall survival than patients with residual disease. Conclusions: This study validates the prognostic stratification of patients with a complete pathologic axillary response to neoadjuvant chemotherapy. The addition of SLN biopsy to cN0 patients before treatment increased accurate nodal staging by 53%, eliminated completion axillary lymph node dissection in 15%, and demonstrated an improved prognosis in 28% of pCR^AX patients. SLN biopsy before treatment provides accurate staging of cN0 patients; allows acquisition of standard treatment markers, prognostic biomarkers, and microarray analysis; and affords prognostic stratification after treatment.