ERBB2 and breast cancer: Most notable are the newer propensity-matched analyses, such as one by Parsons et al., which examined data from the National Cancer Database (NCDB) from 5720 T1N0 HER + BC patients with untreated disease, then propensity-matched them 1:1 to 15,428 T1N0 HER2 + BC patients who received systemic therapy with or without anti-HER2 agents17.