Impact of neoadjuvant chemotherapy on pathologic axillary nodal status in HER-2 positive patients presenting with clinically node-negative disease

Objectives We investigated the impact of neoadjuvant chemotherapy (NAC) on axillary disease burden in clinically node-negative (cN0) HER-2 positive breast cancer patients. Methods We studied 215 cN0 patients with HER-2 positive tumors. Multivariable logistic regression was used to compare NAC versus primary surgery (PS) with respect to outcome of pathologic nodal disease. Results Of 215 patients, 42 (20%) received NAC. NAC use correlated with higher clinical T stage (P < 0.0001) and younger age (P = 0.03) with no difference in ER/PR status or tumor grade. Despite higher clinical T stage in the NAC group, rate of pathologic positive axillary nodes was non-significantly lower (NAC 5/42 = 11.9%, PS 27/173 = 15.6%, P = 0.54). In multivariable analysis, after adjustment for confounders including clinical T stage, age, and multifocal/multicentric disease, NAC showed significant reduction in odds of pathologic nodal disease (OR 0.26, 95%CI:0.06-0.90, P = 0.03). Further, among those with pathologic nodal disease, the number of positive nodes was lower after NAC (adjusted P = 0.03). Extranodal extension was present in 8/27 (30%) PS patients vs. 1/5 (20%) of the NAC patients (adjusted P = 0.36). Conclusion NAC in cN0 HER-2 positive breast cancers reduces the rate of pathologic node-positive disease at operation and nodal disease burden and may decrease the need for axillary node dissection.