Abstract

Purpose
The use of neoadjuvant chemotherapy (NAC) in cT1N0 patients with triple-negative (TN) or HER2-positive (HER2+) breast cancer has been controversial. It is unclear whether NAC or upfront surgery minimizes axillary dissection (ALND) risk in the contemporary cT1N0 TN/HER2+ patient population.
Methods
Consecutive cT1N0 TN/HER2+ patients who received NAC or underwent upfront surgery at our institution between 01/2020–12/2022 were examined. ALND was indicated for any positive sentinel nodes (+SLNs) after NAC, ≥3 positive SLNs after upfront surgery, or 1–2 positive SLNs after upfront mastectomy not requiring radiotherapy (RT). Clinicopathologic features, nodal burden, and ALND rates were compared between NAC versus upfront surgery cohorts.
Results
Among 506 patients, 43% (N=218) were TN and 57% (N=288) were HER2+; 9% (N=47) received NAC before surgery; 68%( N=343) underwent upfront breast-conserving surgery (BCS); 23% (N=116) underwent upfront mastectomy.
Axillary ultrasound was performed in 23% of patients who received NAC versus 26% of patients who underwent upfront BCS versus 33% of patients who underwent upfront mastectomy. ALND was performed in 6.4% (N=3) of patients with any positive SLN after NAC, 1.7% (N=6) who underwent upfront BCS, and 1.7% (N=2) who underwent upfront mastectomy with≥3 positive SLNs or 1–2 positive SLNs not meeting RT criteria (p=0.13). No factors were associated with ALND, including T stage, upfront versus NAC approach, or tumor subtype.
Conclusion
Nodal disease burden is low among cT1N0 TN/HER2+ patients even in the absence of routine axillary ultrasound. ALND was performed in<2% of patients with cT1N0 TN/HER2+ disease who had upfront surgery, and adjuvant systemic therapy was de-escalated among many pathologically node-negative patients following surgery.