Barron AU, et al. - Researchers evaluated the National Cancer Database (NCDB), including 30,821 patients with cT1/cT2 N0/N1 breast cancer treated with neoadjuvant chemotherapy (NAC) and surgical resection, to assess rates of nodal positivity in patients with cT1/cT2 N0 ERBB2 (formerly known as HER2)-positive disease and triple-negative breast cancer (TNBC) with a breast pathologic complete response (pCR) following NAC. Findings revealed ERBB2-positive disease and TNBC had the highest rates of breast pCR. The nodal positivity rate was under 2% in patients with clinically node-negative (cN0) ERBB2-positive disease or TNBC with breast pCR. This supports that, in this subset of patients, the omission of axillary surgery could be considered.

Methods

• Data from the NCDB from January 1, 2010 through December 31, 2015 was retrospectively reviewed.
• Patients with cN0/cN1 cT1/cT2 breast cancer who had NAC then surgery were included.
• Researchers compared the pathologic nodal positivity rates by breast pCR in cN0 and cN1 disease, within each tumor subtype (ERBB2-positive, TNBC, and hormone receptor–positive/ERBB2-negative).
• Data were analyzed from September 13, 2017 through January 30, 2018.
• They assessed the pathologic nodal positivity rate after NAC (ypN), particularly in patients with cT1/cT2 cN0 ERBB2-positive disease or TNBC who attain a breast pCR after NAC.

Results

• Researchers identified 6,802 patients with cN0 ERBB2-positive disease; breast pCR was achieved in 3,062/6,802 (45.0%) patients; 49/3,062 (1.6%; 95% CI, 1.2%-2.1%) were ypN positive.
• They identified 6,222 patients with cN0 TNBC; breast pCR was achieved in 2,315/6,222 (37.2%) patients; 36/2,315 (1.6%; 95% CI, 1.1%-2.1%) were pathologic node positive following NAC.
• Patients with cN0 and residual disease in the breast showed higher rates of ypN positivity; 632 of 3,740 (16.9%) with ERBB2-positive disease and 492 of 3,907 (12.6%) with TNBC with residual disease in the breast were node positive (P < .001).
• Among 4,164 patients with cN1 ERBB2-positive disease, breast pCR was achieved in 1,801 (43.3%) patients; 223/1,801 (12.4%) were ypN positive.
• In 3,293 patients with TNBC, breast pCR was achieved in 1,229 (37.3%); 173/1,229 (14.1%) were ypN postive.
• In this work, breast pCR rates were lower in hormone receptor–positive/ERBB2-negative disease (646 of 5,069 [12.7%] for cN0; 711 of 5,271 [13.5%] for cN1) and there was ypN positivity in 26 of 646 (4.0%) in cN0 vs 217 of 711 (30.5%) in cN1 disease with breast pCR and 1,464 of 4,423 (33.1%) in cN0 disease vs 3,775 of 4,560 (82.8%) in cN1 disease with residual disease in the breast.