Association of Low Nodal Positivity Rate Among Patients With ERBB2-Positive or Triple-Negative Breast Cancer and Breast Pathologic Complete Response to Neoadjuvant Chemotherapy.

IMPORTANCE

A recent publication reported that of 527 patients with clinically node-negative (cN0) cT1/cT2 triple-negative breast cancer (TNBC) or ERBB2-positive disease treated with neoadjuvant chemotherapy (NAC), 100% of those who achieved a breast pathologic complete response (pCR) had pathologic node negativity (pN0). Eliminating axillary surgery in these patients has been suggested as safe based on these results.

OBJECTIVE

To evaluate nodal positivity rates in patients with cT1/cT2 N0 ERBB2-positive disease and TNBC with a breast pCR after NAC using the National Cancer Database (NCDB), which included academic and community settings.

DESIGN, SETTING, AND PARTICIPANTS: This retrospective study reviewed data from the NCDB from January 1, 2010, through December 31, 2015. Participants included patients with cN0/cN1 cT1/cT2 breast cancer who received NAC followed by surgery. Pathologic nodal positivity rates by breast pCR were compared 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.

EXPOSURES

Neoadjuvant chemotherapy followed by surgery.

MAIN OUTCOMES AND MEASURES

The pathologic nodal positivity rate after NAC (ypN) specifically in patients with cT1/cT2 cN0 ERBB2-positive disease or TNBC who achieve a breast pCR after NAC.

RESULTS

A total of 30 821 patients with cT1/cT2 cN0/cN1 breast cancer treated with NAC and surgical resection (99.6% female; mean [SD] age, 52.0 [11.5] years) were identified. Of 6802 patients with cN0 ERBB2-positive disease, 3062 (45.0%) achieved breast pCR and of those, 49 (1.6%; 95% CI, 1.2%-2.1%) were ypN positive. In 6222 patients with cN0 TNBC, 2315 (37.2%) achieved breast pCR, and of those, 36 (1.6%; 95% CI, 1.1%-2.1%) were pathologic node positive after NAC. Rates of ypN positivity were higher in patients with cN0 and residual disease in the breast; 632 of 3740 (16.9%) with ERBB2-positive disease and 492 of 3907 (12.6%) with TNBC with residual disease in the breast were node positive (P < .001). Among 4164 patients with cN1 ERBB2-positive disease, 1801 (43.3%) achieved breast pCR, with 223 of those (12.4%) being ypN positive. In 3293 patients with TNBC, 1229 (37.3%) achieved breast pCR, with 173 of these (14.1%) being ypN postive. Breast pCR rates were lower in hormone receptor-positive/ERBB2-negative disease (646 of 5069 [12.7%] for cN0; 711 of 5271 [13.5%] for cN1) and ypN positivity rates were 26 of 646 (4.0%) in cN0 vs 217 of 711 (30.5%) in cN1 disease with breast pCR and 1464 of 4423 (33.1%) in cN0 disease vs 3775 of 4560 (82.8%) in cN1 disease with residual disease in the breast.

CONCLUSIONS AND RELEVANCE

In this study, the highest rates of breast pCR were seen in ERBB2-positive disease and TNBC. In patients with cN0 ERBB2-positive disease or TNBC with breast pCR, the nodal positivity rate was less than 2%, which supports consideration of omission of axillary surgery in this subset of patients.