Barron AU, et al. - Researchers used the National Cancer Database (NCDB) to estimate the nodal positivity rates in cases with cT1/cT2 N0 ERBB2-positive disease and triple-negative breast cancer (TNBC) with a breast pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC). They found the highest rates of breast pCR in ERBB2-positive disease and TNBC. The nodal positivity rate was observed less than 2% in cases with cN0 ERBB2-positive disease or TNBC with breast pCR supporting the consideration of omission of axillary surgery.

Methods

• In this retrospective study, they examined the data from the NCDB (January 1, 2010, to December 31, 2015).
• They involved participants with cN0/cN1 cT1/cT2 breast cancer who were given NAC followed by surgery.
• They compared 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).
• They estimated the data from September 13, 2017, to January 30, 2018.
• Exposures included neoadjuvant chemotherapy followed by surgery were given.
• Main outcomes and measures included the pathologic nodal positivity rate after NAC (ypN) specifically in cases with cT1/cT2 cN0 ERBB2-positive disease or TNBC who achieved a breast pCR after NAC.

Results

• They identified 30,821 cases with cT1/cT2 cN0/cN1 breast cancer treated with NAC and surgical resection (99.6% female; mean [SD] age, 52.0 [11.5] years).
• A total of 3062 (45.0%) candidates out of 6802 cases with cN0 ERBB2-positive disease achieved breast pCR and of those, 49 (1.6%; 95% CI, 1.2%-2.1%) were ypN positive.
• Thirty six (1.6%; 95% CI, 1.1%-2.1%) were observed pathologic node positive after NAC in 6222 subjects with cN0 TNBC, 2315 (37.2%) who achieved breast pCR.
• They noted higher rates of ypN positivity in subjects 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).
• A sum of 1801 (43.3%) cases achieved breast pCR, with 223 of those (12.4%) being ypN positive among 4164 patients with cN ERBB2-positive disease.
• Among 3293 participants with TNBC, 1229 (37.3%) recieved breast pCR, with 173 of these (14.1%) being ypN postive.
• Breast pCR rates were observed 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.