ERBB2 and breast cancer: In contrast, patients of N2 (P = 0.005, OR = 1.747 [95% CI: 1.182–2.583]) and N3 (P = 0.000, OR = 2.866 [95% CI: 1.683–4.879]) stage were more likely to have HER2 positive breast cancer than patients of N0 stage.