Abstract
Neoadjuvant chemotherapy (NAC) is used to allow more limited breast surgery without compromising local control. We sought to evaluate nationwide surgical trends in patients with operable breast cancer treated with NAC and factors associated with surgical type. We used the National Cancer Database to identify 235,339 women with unilateral T1-3 N0-3 M0 breast cancer diagnosed between 2010 and 2014 and treated with surgery and chemotherapy. Of these, 59,568 patients (25.3%) were treated with NAC. Rates of pathological complete response (pCR) to NAC increased from 33.3% at the start of the study period in 2010 to 46.3% at the end of the period in 2014 (p = 0.02). Rates of breast-conserving surgery (BSC) changed little, from 37.0 to 40.8% (p = 0.22). Although rates of unilateral mastectomy decreased from 43.3 to 34.7% (p = 0.02) and rates of bilateral mastectomy without immediate reconstruction remained similar (11.7-11.5%; p = 0.82), rates of bilateral mastectomy with immediate reconstruction rose from 8.0 to 13.1% (p = 0.02). Patients who were younger, with private/managed care insurance, and diagnosed in more recent years were more likely to achieve pCR; however, these same characteristics were associated with receipt of bilateral mastectomy (vs. BCS). In addition, non-Hispanic white ethnic and higher area education attainment were both associated with bilateral mastectomy. These findings did not differ by age or molecular subtype. Further study of nonclinical factors that influence selection of more extensive surgery despite excellent response to NAC is warranted.